The spectroscopy of nuclei, atoms, ions and molecules belongs today to the group of the most important and most widespread methods of instrumental analytics. High-tech emission, absorption and fluorescence spectrometers provide accurate determination of the qualitative and quantitative composition of gaseous, liquid and solid substances, allow you to study the surface layers of materials, conduct local and layer-by-layer analysis. This monograph provides an overview of various modern methods of nuclear, atomic, ionic and molecular spectrometry, as well as instruments that implement these methods. Many analytical problems solved in laboratories of industrial enterprises, in natural science and technical institutions, as well as issues of studying and protecting environmental objects are considered.

Track analytics.
The methods of classical analytical chemistry, which give extremely accurate results when determining the content, up to a thousandth of a percent, are based mainly on chemical reactions, including precipitation reactions of sparingly soluble products (gravimetry) or intensely colored products (titrimetry). Since the elements to be studied are in the form of ions in an aqueous solution, we can speak of "wet" methods of chemical analysis. These classic ultra-low volume methods are no longer suitable for cost-effective laboratory analytics in the trace range.

If, for example, it is necessary to perform a quantitative determination of the concentration of an element of 1 ng / g in a cell, then a determination method with an absolute detectivity in the femtogram range (1 fg \u003d 10 ~ 15 g) will already be required. It is clear that analytical information in this case should still be sufficiently reliable. The doubtfulness of the obtained data is not excluded today at all phases of the analytical process, when it is necessary to determine negligible concentrations in units of ng/g and below. The reason for this situation is the presence of systematic errors, which in traditional analyzes are only of secondary importance, but their role increases sharply when determining an ever lower content of elements.

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The spectroscopy of nuclei, atoms, ions and molecules belongs today to the group of the most important and most widespread methods of instrumental analytics. High-tech emission, absorption and fluorescence spectrometers provide accurate determination of the qualitative and quantitative composition of gaseous, liquid and solid substances, allow you to study the surface layers of materials, conduct local and layer-by-layer analysis. This monograph provides an overview of various modern methods of nuclear, atomic, ionic and molecular spectrometry, as well as instruments that implement these methods. Many analytical problems solved in laboratories of industrial enterprises, in natural science and technical institutions, as well as issues of studying and protecting environmental objects are considered.

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Contents Preface .................................................................. ................................................. ................. 17 From the Author .................................. ................................................. ............................................... 18 Chapter 1. Introduction....... ................................................. ................................................. .. 22 1.1. History reference................................................ ............................................... 24 1.2. Benefits of instrumental analytics ............................................................... .. 26 1.2.1. Follow-up analytics................................................... .................................. 27 1.2.2. High Sample Turnover ............................................... .................................. 28 1.3. Spectroscopy................................................. ................................................. 29 1.4. "Nothing": how to find it .............................................. ............................................... 33 1.4.1. Example: platinum ............................................... ................................................. 37 1.4.2. Limitations of trace analytics............................................................... ............. 38 1.4.3. The way to the best methods of trace analysis............................................... 39 1.4.4. Sampling ............................................................... ................................................. 42 1.5 . Trends in the development of analytics of environmental objects .............................. 43 Chapter 2. Interaction between light and matter .............. ......................................... 50 2.1. Internal and external interactions .............................................................. ........... 51 2.2. Absorption and emission spectroscopy ............................................................... 52 2.3. Atomic and molecular spectroscopy ............................................................... ........... 53 2.4. Excitation conditions ..........; ................................................. ....................................... 55 2.5. Classification of Spectrum Regions .................................................................. ................................... 57 2.6. Measuring systems for spectroscopy............................................................... .......... 58 2.6.1. Place of absorption .............................................................. .................................... 58 2.6.2. Absorption rate................................... ................................................. .. 59 2.6.2.1. Population ratio .................................................................. ................ 59 2.6.2.2. Transition Probability .............................................................. ....................... 60 2.6.2.3. Lambert-Beer law .............................................. ....................... 60 2.7. Quantitative and qualitative analysis .............................................................. ........ 61 2.7.1. Qualitative analysis .............................................................. .................................. 62 2.7.2. Quantitative analysis ................................................................ ........................... 62 2.8. Conventional spectrometer .................................................................. ............................... 64 2.8.1. Single-beam spectrometers .............................................................. ................................... 66 2.8.2. Double-beam spectrometers .................................................................. ...................... 66 Chapter 3. Spectroscopy in the UV> and visible regions of the spectrum .................. ....................... 68 3.1. Classification of electronic transitions ............................................................... .......... 69 3.1.1. The Franck-Condon principle .................................................................. ...................... 70 3.2. Theoretical calculation of electronic transitions............................................................... .. 71 3.2.1. Dissociation energy and ionization potential .............................................. 73 3.2.2. Chromophores .................................................. ............................................... 73 3.3. Allowed and prohibited transitions .......................................................... .............. 76 3.4. Measuring principle .................................................................. ......................................... 77 3.4.1. Sources of light................................................ ............................................... 78 3.4.2. Monochromator .................................................. ......................................... 80 3.4.3. Detector................................................. ................................................. .. 80 3.4.4. Cuvettes ................................................. ................................................. ... 82 3.5. Spectrum measurement .............................................................. ............................................... 82 3.5.1. Fine vibrational structure .......................... ............................................... 83 3.6. Determination of concentration by color ....................................................... .............. 85 3.7. Multi-component analysis .................................................................. ....................................... 86 6 Contents 3.8. Dual Wavelength Measurement .................................................................. .... 88 3.9. Difference spectra .................................................................. ......................................... 90 3.10. Derivative Spectra .................................................................. ............................................... 91 3.11. Requirements for a modern spectrometer....................................................... ...... 92 3.12. Diode Arrays in UV and Visible Spectroscopy .............................. 94 3.12.1. Conventional spectrophotometer .................................................................. ........... 96 3.12.2. Diode array spectrophotometers ............................................................... 97 3.12.3. Benefits of Diode Array Technology............................................................... 98 3.12.3.1 . Single-beam devices .............................................................. .................... 98 3.12.3.2. Express registration of spectral data .............................. 100 3.12.3.3. Simultaneous Spectrum Measurement .............................................. 100 3.12 .3.4. Wavelength reproducibility ............................................................... ...... 100 3.12.3.5. Measuring range ................................................................ ......................... 101 3.12.3.6. Measurement Data Statistics .................................................................. ...... 101 3.13. Pairing with light guides .............................................................. ......................... 102 3.13.1. Theoretical foundations of the functioning of light guides .............................. 102 3.13.2. Application of the light guide system .................................................................. ........ 103 3.14. Express>tests in the study of water .............................................. .......... 105 3.14.1. Example: Photometric Determination of Traces of Copper .......................................... 107 3.14.2. Rod indicators .................................................................. ...................... 107 3.14.3. Sets for comparative express>tests (colorimetry) ........... 108 3.14.4. Small-sized photometers with ready-made programs....................... 110 3.14.5. Reference beam method ............................................................... ................. .......... 111 3.15. Summary and Prospects for the Development of UV and Visible Spectroscopy .............. 112 Chapter 4. Fluorometry .................................. ................................................. ................. 4.1. Theoretical foundations of luminescence............................................................... .......... 4.2. Fluorescence .............................................................. ............................................... 4.3. Phosphorescence................................................. ............................................... 4.4. Measurement parameters for fluorometry............................................................... ....... 4.4.1. Quantum yield of fluorescence .............................................................. ........... 4.4.2. Quantitative analysis ................................................................ ......................... 4.4.3. Quenching of fluorescence .................................................................. ......................... 4.4.4. Fluorescent indicators .................................................................. ................. 4.5. Fluorescence spectrometers.................................................................... ...................... 4.5.1. Different types of spectra ............................................................... ............................... 4.5.2. Spectrum Correction .................................................. ................................. 4.5.3. Scattering of light.............................................. ............................................... 4.5.4. Other possible errors .................................................................. ............ 4.6. Sample carriers (holders) ............................................... ............................... 4.7. Temperature effect .................................................................. ............................................... 4.8. Fluorescence induced by laser radiation.................................................... 4.9. Time-Resolved Fluorometry .............................................................. ........ 4.10. Summary and prospects for the development of fluorometry .............................................. 116 116 118 121 123 123 124 125 126 126 128 129 131 132 133 134 135 136 137 ................................................. .......... 5.1. History reference................................................ ................................................... 5.2. Principle of IR>spectroscopy .............................................................. ...................... 5.2.1. Selection rules.... ................................................. ................................. 5.3. IR>spectrum.............................................. ................................................. ....... 5.4. Interpretation of spectra .................................................................. ................................. 5.4.1. Theoretical foundations of IR>spectroscopy .............................................. 5.4. 1.1. Harmonic oscillator .................................................................. ............ 138 139 140 141 142 144 144 144 8 Contents 5.4.1.2. Anharmonic oscillator .................................................................. ....... 5.4.1.3. Polyatomic molecules .................................................................. ............... 5.4.2. Empirical approach to the interpretation of spectra .............................................. 5.5. Instruments and equipment for recording IR>spectra .............................................. 5.5.1. Conventional IR>spectrometers............................................................... ............ 5.5.2. Fourier transform IR>spectrometers.............................................. ......................... 5.5.2.1. Michelson interferometer.................................................... ........ 5.5.2.2. Advantages of the IR Fourier>spectrometer .............................................. 5.5. 3. Qualitative analysis .............................................................. ............................... 5.5.4. Quantitative analysis ................................................................ ......................... 5.6. Sample preparation methods .................................................................. ......................... 5.6.1. Liquids and solutions ............................................................... ............................... 5.6.2. Solids .................................................................. .................................... 5.6.2.1. Pressing technique with KBr ............................................... .............. 5.6.2.2. Sample preparation procedure with paraffin oil .............................. 5.6.3. Gases ................................................. ................................................. ....... 5.7. IR>reflection spectroscopy...................................................... ......................... 5.7.1. ATR method................................................... ................................................. 5.7.1.1. The principle of the frustrated total internal reflection method .............................................................. ............................................... 5.7.1.2. Practical application of IR>ATR spectroscopy. ............... 5.7.2. External reflection in IR>spectroscopy....................................................... 5.7.2.1. Mirror reflection................................................ .................... 5.7.2.2. Glancing reflection spectroscopy .............................................. 5.7.2.3. Diffuse Reflection .................................................................. .................... 5.7.2.4. Practical application of reflectance spectroscopy ......... 5.7.2.5. Interfacing with optical fibers .............................................................. 5.8. Photoacoustic detection .................................................................. ......................... 5.9. IR>microscopy....................................................... ............................................... 5.9.1. Technique and methods of IR>microscopy .............................................. ...... 5.9.2. Specimens for IR>microscopy....................................................... ................. 5.10. Joint application of analytical methods .......................................................... 5.10.1. Combination of gas chromatography and IR Fourier>spectroscopy....... 5.10.2. Combination of thermogravimetric analysis with Fourier>spectroscopy .............................................................. ............................... 5.11. Application of computers in IR>spectroscopy .............................................. .......... 5.12. Summary and prospects for the development of IR>spectroscopy .............................. 147 150 150 154 156 157 158 159 160 161 162 162 164 165 166 167 169 171 Chapter 6. Spectroscopy in the near IR> region................................. ...................... 6.1. Differences in the spectroscopy of the near and mid-IR>region .......................... 6.2. Spectrometer for near-IR>region .............................................. ............. 6.3. Practical application of spectroscopy in the near IR> region .............. 6.3.1. Determination of moisture content................................................... ............... 6.3.2. Use of NIR Spectroscopy in Plastics Recycling.................................................................................. .......... 6.4. Summary and prospects for the development of spectroscopy in the near IR region ........ 196 196 198 199 201 Chapter 7. Raman spectroscopy ............ ......................... 7.1. Theoretical foundations of Raman spectroscopy .......... 7.2. Selection rules .................................................. ............................................... ... 7.3. Raman spectrometer.................................................................... .... 7.4. Practical application of Raman spectroscopy .............................................................. ................................................. .......... 171 174 176 176 177 179 182 182 183 185 186 187 188 189 190 192 193 202 203 205 206 209 210 213 10 Content 7.5. Summary and prospects for the development of Raman spectroscopy .............................................................. ................................................. .............. 214 Chapter 8. Microwave spectroscopy .............................. .................................... 8.1. Theory of rotational spectra .............................................................. ............................... 8.2. Microwave>spectrometer............................................... ............................................... 8.3. Practical application of microwave spectroscopy .............................................. 8.3.1. Determination of interatomic distances and bond angles .......... 8.3.2. Determination of dipole moments ............................................................... ......... 8.3.3. Nuclear>quadrupole conjugation............................................................... ......... 8.4. Summary and prospects for the development of microwave spectroscopy 216 217 220 221 222 222 223 224 Chapter 9. Atomic absorption spectroscopy .............. ......................................... 9.1. History reference................................................ ................................................. 9.2. General characteristics of the method ............................................... ......................... 9.3. Line Spectrum .................................................................. ......................................... 9.3.1. Selection rules .................................................. ................................................. 9.3.2. Line selection .............................................................. ............................................... 9.3.3. Sensitivity and limits of detection............................................................... 9.4. Atomic absorption spectrometer............................................................... .............. 9.4.1. Modulation principle and spectral interference .............................................. 9.4.2. Spectral Line Width .................................................................. ................. 9.5. Hollow cathode lamps .............................................................. ................................. ... 9.5.1. Multi-element hollow cathode lamps.................................................................... 9.5.2 . Electrodeless discharge lamps .................................................................. .......... 9.6. Atomization process .................................................................. ............................................... 9.6.1. Atomization in the flame .............................................................. ............................... 9.6.1.1. The flame of a mixture of air and acetylene ............................................... ..... 9.6.1.2. Flame of a mixture of laughing gas and acetylene .................................................... 9.6.1.3. Nozzles and mixing chambers .......................................................... 9.6.1.4 . Graduation and Graph Correction .............................................................. ... 9.6.2. Atomization in a graphite tube furnace .............................................................. 9.6.2.1. Super high heating speed .................................................................. ...... 9.6.2.2. Lvov platform .................................................. ................................. 9.6.2.3. Temperature drop and inert gas flow interruption ........ 9.6.2.4. Signal Area Integration .................................................................. .. 9.6.2.5. Graphical support of the atomization process .............................. 9.6.2.6. Matrix modification .................................................................. ................. 9.6.3. Technique based on hydride compounds and cold mercury vapor ...... 9.6.4. Criteria for selecting a suitable atomic>absorption spectroscopy method .............................................................................. ............................................... 9.7. Interference................................................. ................................................. .......... 9.7.1. Chemical Interference .................................................................. ................................. 9.7.2. Physical interference .................................................................. ................................. 9.7.3. Ionization interference .............................................................. ......................... 9.7.4. Spectral interference .............................................................. ............................... 9.7.5. Addition method .................................................................. ......................................... 9.8. Background absorbance .............................................................. ......................................... 9.8.1. Compensation with Continuous Light Emitters............................................... 9.8.2. Zeeman background correction. ................................................. ................ 9.8.2.1. Zeeman effect .................................................................. ............................... 9.8.2.2. Different systems of atomic>absorption spectrometry using the Zeeman effect.................................................................................. ...266 229 230 230 232 234 235 236 237 238 239 240 241 241 241 242 242 243 246 247 251 252 253 253 254 255 257 258 258 258 260 261 262 264 266 266 268 12 Content 9.8.2.3 . Limits of Zeeman background correction ............................................... 9.8.3. Smith-Hifty system .............................................. ........................... 9.9. Hardware design of the process .................................................... ............... 9.9.1. Defining Multiple Elements at the Same Time............................ 9.10. Flow>injection analysis in atomic>absorption spectrometry .............................................................. ................................................. .... 9.10.1. Flow-through>injection atomic>absorption spectrometry based on the determination of hydrides and mercury........................................................... ....... 9.10.2. Flow-through>injection flame atomic>absorption spectrometry.................................................................. ............................................... 9.10.3. Through-flow injection combined with a high-pressure spray system .............................................................. ............................................... 9.10.3.1. Combination with ion chromatography............................................................... 9.10.3.2. Concentration of elements and separation of the matrix .............................. 9.10.4. Prospects for the use of flow injection in atomic>absorption spectrometry .............................................................. .. 9.11. Equipment of the laboratory of atomic>absorption spectrometry .............. 9.11.1. Exhaust system when working with flame atomic>absorption spectrometry .............................................................................. ............................................... 9.11.2. Workspace................................................ ............................... 9.1.3. Burner drain .......................................................... ............................................... 9.12. Summary and prospects for the development of atomic>absorption spectroscopy .............................................................. ................................................. ... 273 275 277 283 284 286 287 289 291 292 294 294 295 295 296 297 Chapter 10. Atomic>fluorescence spectrometry .............................................................. ...... 300 Chapter 11. Atomic spectrometry with plasmas .................................................. ....................... 11.1. Theoretical foundations of the method............................................................... ......................... 11.1.1. What is plasma? ................................................. ................................. 11.2. Plasma formation .................................................................. ............................................... 11.2.1. Inductively coupled plasma ............................................................... ............... 11.2.2. Three-electrode direct current plasma............................................................... 11.2.3. Microwave>induced plasma............................................................... ................. 11.3. Composition of an atomic>emission spectrometer with ICP ....................................................... 11.3.1. High Frequency Generator .................................................................. .................... 11.3.2. Plasma torch system .............................................................. ................ 11.3.2.1. Burners................................................. ......................................... 11.3.2.2. Different modes of operation .................................................................. ................. 11.3.2.3. Spraying................................................................. ................................... 11.3.2.4. Spray chamber .................................................................. ................ 11.3.2.5. On the issue of reducing the consumption of argon .......................................................... 11.4. Equipment for working with ICP ....................................................... .................... 11.4.1. Emission ICP>sequential spectrometers...... 11.4.1.1. Monochromator of the sequential spectrometer ........ 11.4.1.2. Resolution................................................ ........... 11.4.1.3. Czerny-Turner monochromator .............................................. .... 11.4.1.4. ICP>Analytics in Spectral Peak .......................................................... 11.4.2 . Multi-element emission ICP>spectrometer .................................. 11.4.2.1. Paschen-Runge polychromator...................................................... ...... 11.4.3. Combined ICP>Simultaneous and Sequential Spectrometers.................................................................................. ................... 11.4.4. ICP>echelle spectrometer....................................... ................................... 303 306 308 309 310 312 313 315 315 316 316 318 321 325 326 326 328 329 330 333 333 335 337 338 338 Content 11.4.4.1. Simultaneous measurement of all elements at all wavelengths .......................................................... ............................... 11.4.5. Problems of multi-element definition .......................................................... 11.4.6. Light guides for ICP>spectrometers....................................................... ....... 11.4.7. Plasma Observation in the Axial Direction .......................................................... 11.4.8. Application of the internal standard ............................................................... ...... 11.5. Interference in optical emission ICP>spectrometry .................................................. 11.5.1. Background noise .................................................................. .................................... 11.5.1.1. Scattered light .............................................................. ............................... 11.5.1.2. Spectral interference .............................................................. ................... 11.5.2. Recognition and compensation of background noise.................................................... 11.5.2.1. Measuring a blank solution ............................................................... 1.5.2.2 . Review analysis .................................................................. ............................... 11.5.2.3. Transition to other lines of the spectrum ............................................... ... 11.5.2.4. Measuring the background next to the analytical line .............................. 11.6. Standard solutions for atomic>emission spectrometry ............... 11.7. Hydride system ................................................................ ......................................... 11.8. Analysis of solid samples.................................................................... ............................... 11.8.1. Spark emission spectrometry ............................................................... 11.8.2. Glow Discharge ................................................................ .................................... 11.8.3. Microplasmas induced by laser radiation ............................. 11.8.4. Graphite tube furnace method.................................................................... ......... 11.9. Selecting a Spectrometer for Elemental Analysis....................................................... 11.9 .one. Limits of detection.............................................................. ........................... 11.9.2. Linear Dynamic Workspace.................................................................... 11.9. 3. Measuring speed.................. ................................................. .......... 11.9.4. Interference................................................. ................................................. 11.9.5. Reproducibility ................................................................ ............................... 11.9.6. Other important aspects ............................................................... ......................... 11.10. Plasma mass>spectrometry...................................................... ................. 11.10.1. Technique and methods of ICP mass spectrometry .............................................. 11.10.2. ICP as an ion source ............................................................... ...... 11.10.3. Interface of mass>spectrometry with ICP .............................................. 11.10.4. Mass>spectrometers............................................... ............................... 11.10.5. Benefits of Plasma Mass Spectrometry ....................................................... 11.10.5.1. Semi-quantitative analysis .............................................................. ...... 11.10.5.2. Defined Elements .................................................................. ............. 11.10.5.3. Analytical Limitations .................................................................. ...... 11.10.6. New Applications of Plasma Mass Spectrometry........ 11.11. Summary and prospects for the development of plasma atomic spectrometry .............................................................. ................................................. ... Chapter 12. Mass>spectrometry .......................................... ...................................... 12.1. Theoretical foundations of the method............................................................... ......................... 12.2. The nature of the mass spectrum .......................................................... ............................................... 12.2.1. Stability of ions>fragments............................................... ........... 12.2.2. Rearrangements .................................................................. ................................. 12.2.3. Metastable ions .............................................................. ......................... 12.3. Ion formation .................................................................. ................................................. 12.3.1. Ionization by electron impact .............................................................. ........... 12.3.2. Chemical ionization .................................................................. ......................... 12.3.3. Mass>spectrometry based on ion>molecular reactions.......... 13 341 342 343 344 345 345 346 346 347 348 349 350 351 351 352 352 353 353 355 357 357 358 360 361 361 36 36 366 367 367 369 369 369 370 372 376 377 378 379 380 380 381 381 382 383 14 Contents 12. 3.4. Time-of-flight mass>spectrometry with laser desorption>ionization from a matrix.................................................................. ............ 12.3.5. Mass>spectral analysis of non-volatile compounds .................................. 12.3.6. Mass>negative ion spectrometry .......................................................... 12.4. Mass>spectrometers............................................... .................................................. 12.4.1. Quadrupole mass>spectrometer....................................................... ......... 12.4.2. Magnetic mass>spectrometer....................................................... ................ 12.4.3. Time-of-flight mass>spectrometers............................................................... .... 12.4.4. Dual (tandem) mass>spectrometer .......................................................... 12.5. Summary and prospects for the development of mass spectrometry ............................................. 384 384 385 386 387 389 390 391 393 Chapter 13 Nuclear Magnetic Resonance Spectroscopy .............................................................. 13.1. Theoretical foundations of NMR>spectroscopy....................................................... .. 13.2. Chemical shift .................................................................. ......................................... 13.3. Spin>spin interaction....................................................... ................... 13.4. Registration of NMR>spectra .............................................. ............................... 13.4.1. To the question of sensitivity .............................................................. ................ 13.4.2. Substance consumption .................................................. ............................................... 13.4.3. Spectra accumulation .................................................................. ............................... 13.4.4. Principles of integration ................................................................ ................. 13.4.5. Quantitative analysis ................................................................ ......................... 13.4.6. A magnetic field................................................ ............................................... 13.5. NMR>spectrometers............................................... ................................................. 13.5.1. Sweep>spectrometer............................................... ................................. 13.5.2. Pulse Fourier>NMR>spectrometer.................................................. ... 13.5.3. Measuring relaxation .................................................................. ......................... 13.6. Double Resonance Technique.... ................................................. ................... 13.7. 2D NMR>spectroscopy....................................................... ................... 13.8. Nuclear Overhauser effect ............................................................... ......................... 13.9. Practical application of NMR>spectroscopy .......................................................... 13.9.1. 13C>NMR>spectroscopy............................................. ......................... 13.9.2. Deuterium NMR>spectroscopy....................................................... ......... 13.9.3. NMR>tomography ............................................... ................................... 13.9.4. NMR>microscopy....................................................... ................................. 13.9.5. Solid State NMR .................................................................. ................................. 13.9.6. Ion cyclotron resonance ............................................................... ......... 13.10. Summary and prospects for the development of NMR>spectroscopy ............................. 395 398 401 404 407 408 409 409 409 410 410 411 413 414 416 417 419 420 421 422 423 424 425 425 427 427 Chapter 14 ............................... 14.1. The concept of X-ray fluorescence ............................................................... ....... 14.2. Theoretical foundations of the method............................................................... ......................... 14.2.1. Auger>effect....................................................... ............................................... 14.2.2. Quantum yield of fluorescence .............................................................. ......... 14.3. Characteristic spectral lines ............................................................... .... 14.3.1. K> spectrum of tin ............................................... ................................................. 14.3.2. L>gold spectrum...................................................... .................................................. 14.4. Moseley's law................................................... ................................................. 14.5. Excitation................................................. ................................................. 14.5.1. Generation of X-rays .............................................................. ............. 14.5.1.1. Bremsstrahlung ......................................................................... 14.5.1.2 . Characteristic radiation ............................................... ............. 14.5.1.3. Choice of anode material .................................................................. ............ 14.6. Absorption of X-rays .............................................................. ................. 430 432 433 435 436 437 437 438 439 440 440 440 441 442 442 16 Contents 14.6.1. Excitation of characteristic radiation .................................................. 14.6.2. Primary and secondary absorption.................................................................... ......... 14.7. X-ray tube.............................................. .................................... 14.7.1. Excitation by radionuclides .............................................................. 14.8. X-ray spectrometers.................................................... ......................... 14.8.1. Wavelength dispersion method .............................................................. ........ 14.8.2. Method with energy dispersion .............................................................. ............... 14.9. X-ray detectors.................................................... ............................... 14.9.1. Scintillation counters .................................................................. ............... 14.9.2. Gas meters .................................................................. ................................... 14.9.3. Semiconductor detectors .................................................................. ............ 14.10. Applications for chemical>analytical purposes.................................................... 14.10.1. Calibration................................................... ......................................... 14.10.2. Limit of detection ........................................................ ........................... 14.11. X-ray fluorescence analysis with total internal reflection .......... 14.12. Measurement of layer thickness by X-ray fluorescence method .............................................................. .......... 14.12.1. Application of selective absorbing films (filters) .......... 14.12.2. Measuring the thickness of the top and intermediate layers................... 14.12.3. Measurement of the thickness of a two-component alloyed layer ........ 14.13. New developments in X-ray spectrometry .................................................. 14.13.1. X-ray fluorescence analysis of light elements ......................................... 14.13.2. Pseudocrystals ................................................................ ................................ 14.14. Summary and prospects for the development of X-ray fluorescence analysis....... 444 445 446 447 447 448 450 451 451 451 452 452 453 455 455 Chapter 15. Surface analysis methods............................................................... ....................... 15.1. Surface analysis methods............................................................... ......................... 15.2. X-ray microanalysis with energy dispersion .............................................. 15.2.1. Qualitative x-ray analysis ............................................................... ... 15.2.2. Quantitative analysis ................................................................ ......................... 15.3. Proton-induced X-ray emission............................................... 15.4. Auger>electron spectroscopy .............................................................. ................... 15.4.1. Scanning Auger>microscope....................................................... .................... 15.5. Electronic spectroscopy for chemical analysis .................................................. 15.6. Mass>Secondary Ion Spectrometry............................................................... ........... 15.7. Ion scattering spectroscopy ............................................................... ............... 15.8. Microscopy with scanning probes .............................................................. ............. 15.8.1. The principle of scanning tunneling microscopy.................................................... 15.8.2. The principle of atomic force microscopy ............................................. 15.8. 3. Magnetodynamic microscope .................................................................. ...... 15.8.4. Scanning electrochemical microscope .......................................................... 15.8.5. Practical application of surface analyzes.................................... 474 476 479 481 482 483 483 486 487 491 493 494 496 498 500 501 501 458 462 464 465 468 468 469 469 Chapter 16. Conclusion....................................................... ................................................. ............ 504 Literature .................................. ................................................. .................................. 507 Further Reading .............................. ................................................. ......... 519 List of firms....................................... ................................................. ......................................... 523 Foreword In connection with the progress in the field of measurement technology and especially microelectronics, the rapid development of instrumental analytics has been noted in the last 10–20 years. , which has also achieved impressive success. Favorable changes in this area required, among other things, an increase in the level of competence of employees of chemical laboratories, from laboratory technicians to chemical researchers, who use various methods of analysis and modern measuring and analytical equipment in their work. Optimal, i.e., problem oriented and close to practice, application of spectroscopy in accordance with the state of the art of analytical technology is now achievable only if one has mastered the basics of new techniques, with precise knowledge of the capabilities and limitations of the proposed equipment and existing analytical systems. Jurgen Becker, a chemical analyst with a wealth of industrial and teaching experience, reviews the most popular and most common spectrometry methods in his book today. The method and technique of analysis are discussed here in a very accessible form with a focus on practical conditions. Each chapter leads the reader from the theoretical foundations to a detailed description of a specific method. By evaluating the advantages and disadvantages, as well as the possibilities and limitations of certain methods and associated analytical equipment, the book teaches a conscious approach to the choice of analytical methods that require a high level of technical equipment, the availability of effective software and guarantee the receipt of reliable and reliable data. Having become acquainted with the above information, the chemical analyst ceases to be a person assigned only to maintain a certain “black box” system and often feels like something like a regulating computer program. Connections and dependencies are opened up before him, helping to optimally use the “analytical tool” at his disposal. With all my heart I wish this book success with interested readers in the hope that the information presented by J. Becker with a detailed description of the methods of analysis and measurement and analytical techniques will contribute to the real development and improvement of modern instrumental analytics. Prof. Georg Schwedt, Technical University, Clausthal Author's note Analytical chemistry, with its traditional questions about the qualitative and quantitative composition of substances, formed the basis of chemistry as a science hundreds of years ago. But by the beginning of the 20th century, there was a certain lag between analytics and the rapidly growing chemistry of synthetic materials, which, thanks to some revolutionary discoveries and ever-increasing demands in the field of natural science, medicine, materials science, technical equipment, and environmental protection, managed to move to the forefront. plan. At the same time, however, the obvious removal of this industry from the needs of practical production, as well as from the pressing problems of the chemical industry itself, did not go unnoticed, while analytical chemistry became more and more confidently the most important economic factor with an emphasis on meeting the needs of the general population. So, it was with the help of chemistry that some problems in the fight against dangerous diseases, many issues of environmental protection, and the economical use of raw materials and energy were successfully solved. If chemical analytics had been put at the service of specific branches of science and technology a little earlier, it would have long ago developed into an independent and highly demanded discipline. Weight and volume analyzes are classified as classical methods for the study of substances by the so-called "wet method". The rapid development of electronics and efficient technologies in the field of instrumentation has led to the fact that chemical-coanalytical techniques have been replaced by more accurate and faster physical methods of detection and identification. Modern chemical analytics is focused on high-level technical equipment. The development of instrumental analytics in combination with electronic data processing has not only expanded the scope of analytical methods, but also made it possible to noticeably lower the previously existing detection limits. At the same time, the duration of the analyzes themselves was sharply reduced. But this does not mean that only expensive instrumental equipment can guarantee complete success, without which one can hardly count on a satisfactory result. Various spectroscopic methods, such as nuclear resonance spectroscopy, IR or mass spectrometry, are widely used today in the search for answers to many questions regarding the structure of molecules or the qualitative and quantitative composition of substances. The development of the chemical sciences and all industries related to them in one way or another depends on the accuracy of the analysis. Every day the importance of instrumental analytics for technological progress in general becomes clearer. Further, it is indispensable at the level of recognition and elimination of factors dangerous to the environment and harmful to human health. These are the areas of application of modern analytics, described briefly and in general, which boost the development of any sphere of science, technology and human activity in general in civilized states. Huge amounts of information obtained as a result of the audit of existing chemical analytical laboratories were taken as the basis for the development of 19 national and international norms and regulations from the author in relation to all areas of science, public health and environmental protection. However, accurate and reliable measurement data have always been and remain a condition for making appropriate and qualified decisions, because even a slight distortion of the results can lead to undesirable consequences. Therefore, in the field of analytics, such key concepts as "quality", "quality assurance" and GLP (gute Laborpraxis - good laboratory practice) determine the conditions under which analytical laboratories must operate. It should be noted here that the requirements for analytics as such are increasing more and more, while the total cost of conducting analyzes, due to strong competition in the market for special equipment, remains practically unchanged. In this regard, a further, rather ambitious goal was set: to achieve the highest possible quality at the lowest possible cost. This was the reason for the large-scale transformation that began today in laboratory practice. Managers and employees of laboratories are obliged to build their work, not least, on the principles of rationality, efficiency and economy. The trend towards universal automation and rationalization is also clearly visible in instrumental analytics. Analytical equipment manufacturers, sensitive to these demands, offer ever more sensitive, more accurate and faster, much more user-friendly instruments and instruments, featuring a high degree of automation at all levels - from sampling and sample preparation to data processing. In achieving this goal, computers with appropriate software provide invaluable assistance. Recently, certain regulations have been developed that offer an unambiguous system of guaranteed quality assurance. In technical terms, conditions are being created for remote maintenance, monitoring and control of complex analytical systems. High-speed networks spread all over the world are designed to realize the global exchange of information between different enterprises and corporations. If earlier the activity of a specialist analyst was limited mainly to quality control of products and the study of the structure of new substances and materials, today analytical research is fully integrated into the overall production process, which provides certain advantages. Previously isolated from each other spheres - "production" and "analytics" - are forced to move to the level of close interaction, in particular, due to the fact that it is the optimization of all processes that can effectively influence the creation of value. An example is the desire to improve the efficiency of routine, that is, everyday and standard, analytics by reducing the cost of laboratory tests, further automation of labor, more convenient maintenance of equipment, making special decisions, express results, ongoing testing of the tools used. control and constant accumulation of experience and knowledge. Automation allows you to perform quite complex analyzes in a simple and reliable way. But at the same time, an analyst must be proficient in modern technologies, have an idea about all promising know-how. It becomes obvious that there is a desire to create certain methodological and technical links between different methods of conducting analyzes with the aim of their joint use. It is thanks to this kind of conjugation, combinations and combinations of spectral methods that analytics, originally oriented towards particular applications, has taken a significant step forward. It is known that with the development of industrial production, a person is increasingly polluting his surrounding world with sewage, waste gases and deposits of various kinds. At the same time, non-decomposing wastes remain in the soil, in water and in the air, sooner or later getting into food and then into the human body. The detection of harmful substances contained in the external environment remains one of the priority tasks of the analytics of environmental objects. Unfortunately, when solving environmental problems, the associated costs often become the determining factor, while the development of the surrounding world, the pressing problems of the economy and society are relegated to the background. Nevertheless, the market for services in the field of analytics, specifically at the level of environmental protection, has changed markedly in recent years, and the need for reliable information has sharply increased. The environmental safety of the production of certain products and products has become a competitive factor at the international level. And yet, there is still an obvious dissonance between the indisputable practical significance of analytical chemistry and the curricula of departments of specialized universities. In Germany, analytics is traditionally associated with inorganic chemistry. The solution of many issues raised at the level of analytical research sometimes requires close interaction at the intersection of sciences with going far beyond the scope of chemistry as such. Working in the field of analytical chemistry is impossible without special knowledge from the field of analytics proper, without a special way of thinking and the ability to make the required strategic decisions. At the same time, success is determined by specific actions at all stages, starting from the correct sampling, their maximum clean preparation (including the optimal choice of the necessary equipment) and ending with the competent processing and interpretation of the obtained data. In contrast to the classical chemical disciplines, the development of analysis methods takes place not only in scientific research institutes or higher educational institutions, but also in factory laboratories and firms engaged in the production of the corresponding equipment. Analytical tools have become simpler in design, easier to handle, and smaller in size. Automated and computerized devices facilitate the process of analysis, but at the same time require a sufficiently high level of qualification of employees. Unfortunately, the reduction in personnel due to ongoing automation of processes is sometimes considered a more important economic factor than the reliability of the results obtained. However, one should not forget that the final evaluation of the method and the interpretation of the data are still carried out by a person, and the computer is only his auxiliary tool. The condition for making good decisions has been and remains reliable and comparable analysis results, which can only be achieved with experienced and well-trained personnel. This book has been conceived with these considerations in mind. Instrumental analytics is not designed for a specialist of such a level who is only able to control machines according to the attached instructions and does not know what exactly he is doing. This tutorial has been written by a practitioner of instrumental analytics focused on a particular application. While studying general chemistry, the author gained a wealth of experience working with "classical" instrumentation (not yet computerized) technology, and later established an instrumental analytics laboratory at the Institute for Process Automation (IPA) in Stuttgart, consistently developing optimal methods for surface investigation. The obtained analytical knowledge was later widely used by IBM in the creation of products based on high technologies. Since 1984, the author has taught a course in instrumental analytics at the Technische Universität Alain as part of his specialization in surface research methods and materials science. Initially, disparate lectures were combined into a common collection, which has been constantly expanded and supplemented in recent years. This publication reflects the current level of development of instrumental methods and demonstrates the possibilities of their application. Both the instrumentation technology used and the methods of instrumental analytics underlying it are as open as possible to innovation and require all users to constantly update and deepen their knowledge. The main goal of the author is to bring to the reader information about the latest developments in the field of instrumental analytics. Qualified personnel of chemical analytical laboratories, students of specialized educational institutions and all specialists, one way or another connected with chemistry, can learn here information about a variety of instrumental methods of analysis and get answers to numerous questions from the field of analytics. For those who are just starting to study the declared subject, quite extensive and sometimes very complex aspects are offered in the most accessible form. At the same time, the theoretical foundations are limited only by the volume necessary for understanding specific methods, while the consideration of the most popular of them is close to practical conditions, indicating the possibilities and limitations, as well as the existing advantages and disadvantages of one or another method. The reader will have a complete understanding of the various methods of instrumental analysis, with a description of the equipment required to implement them. The cited bibliography and numerous references to specialized literature make it possible, if necessary, to seek more detailed information in order to expand and deepen knowledge on relevant issues. Juergen Becker, Stuttgart CHAPTER 1 CAUTION Analytical data is indispensable if the physical, chemical or biological properties of material systems of inorganic or organic nature that we would like to understand, use or change depend on the content of the components of these systems. This applies equally to all aspects of our material world and to many related areas of science and technology that can intersperse and intersect with each other. The material sphere extends from rocks, mineral and organic raw materials, water systems, atmosphere, soil, flora and fauna to the objects of our material needs. First of all, the recognition of impurities capable of changing the properties of chemicals contaminated by them requires an extremely high detection capability with sufficient reliability of information, the costs of obtaining which, of course, should not be excessive. So, the three most important criteria for evaluating an analytical method - sensitivity, correctness and cost - are closely related to each other. Analytical work costs a lot of money, and the cost of conducting analyzes depends to a large extent on the questions posed, the methods used, the reliability of the readings, the complexity of processing, and the total amount of work. Routine laboratory analyzes will certainly cost less than solving complex analytical problems, but this is not a reason to abandon long-term plans. In the situation of dumping policy towards personnel and the desire to reduce the cost of analysis, analytical laboratories with a low level of specialization are especially affected. Since laboratory analyzes using methods according to DIN (German Industrial Standard) or DEV (German Standard Methods for the Study of Water) are sometimes carried out by employees who do not have special knowledge, one should not be surprised at the output of very doubtful results. If we want not just to present some data, so to speak, for pro forma, but to perform precisely the “correct” analyzes, we should entrust the work at all stages - from sampling to evaluating the result - to qualified specialists. Today, the field of application of analytical methods is expanding at an astonishing pace. In technology, these were at first only semiconductors and pure substances, later optical waveguides and superconductors, and now also high-temperature ceramics - in a word, everything that requires the best detectability. The ability to obtain products of reproducible quality is one of the most important conditions for modern production. The methods of analysis currently used are acquiring more and more complex instrumental equipment, which greatly expands their prospects. The variety of methods offered to the user in the field of analytical chemistry corresponds to the variety of areas of their application - from scientific disciplines, such as chemistry, physics, biology and medicine, and to many technological branches. The interaction between the methodical side of analytics and the application-oriented interests of users opens the way for innovation in analytical chemistry, with one goal or another being set, in particular, by the desire for high detection sensitivity, maximum reliability and the most favorable price-performance ratio when using certain analytical methods. In general, it can be noted that in the field of instrumental analytics it has never been possible to measure such a volume of components in such a short time as it is currently being done. The human factor already at the stage of sampling, their preparation and dosage is more than compensated by automation and support from robotics, and the software that performs the functions of an expert system assists in the evaluation of measurement results . In the matter of solving current questions concerning the characterization of substances and materials depending on the analytical task set, the development of new methods based on the already implemented methodology is just as necessary as the improvement of the methods themselves, when the methodological prerequisites for solving emerging problems have yet to be created. In the field of development of elemental analytics, trace analysis methods, as before, remain highly relevant, and special requirements are put forward in relation to the reliability of determination on increasingly complex matrices. This applies to a wide variety of applications, from the creation of new substances to the traditional branches of biology and medicine. Analytics is used ubiquitously in a variety of forms throughout the manufacturing process. Here, four basic concepts are taken as a basis: obtaining active substances, safe operations, quality assurance and environmental protection. But what develops our society more than even innovative technologies, which are indispensable, if only because of the rapid growth of world population? This, of course, is an ever-increasing danger to the environment and, ultimately, to human health and life. Unfortunately, in the modern industrial world, not everyone realizes that without analytical chemistry it will hardly be possible to optimize technologies in the required way and minimize the risks associated with them. Thus, analytics from the category of an initially auxiliary discipline in the service of the chemical industry grows to the level of a fully demanded independent industry, so it will no longer be a big exaggeration to talk about the creation of analytical science as such. Many goals and tasks facing chemists can be reduced to one simple formulation: it is required to find and create substances useful for humans, used as biocatalysts in medicine, veterinary medicine, and agriculture, and also as material for all known or still on the threshold area openings. The sad fact is that Germany has been lagging behind Japan and the United States in this regard over the past few years. It should not be forgotten that omissions at the level of research weaken the economic position of the country in the world market. In fairness, it should be noted that in the field of eco-24 Chapter 1. The introduction of logically pure technologies, which today have become a decisive factor in competition, Germany occupies a leading position in the world. 1.1. Historical background People have been searching for suitable active substances since prehistoric times. While looking for food, they learned to distinguish between edible and poisonous gifts of nature, in the course of their own observations they noted the healing effect of certain herbs, etc. The first reproducible experiments on the use of natural compounds in therapy were also carried out on the basis of traditional medicine. While the impact of a substance on a biological system, be it a person, an animal or a plant, due to the complexity of processes, is not always clear today and requires careful study by specialists in various fields, the first materials necessary for human life were found or created. they are already at an early stage of development. Examples include metals, ceramics and glass, while the discovery of bronze and iron marked the beginning of entire cultural epochs. Previously, a person learned by experience to extract substances with special properties and a special quality. He tried to shape them, harden them, or color them. Taking into account this prehistoric experience, then modern science developed, namely on the basis of analysis and synthesis. Different methods of analysis taught us to understand the composition, purity, structure and quality of the surface. Thanks to the interaction of analysis and synthesis, it was possible to recognize certain properties and structures and then consciously give special features to individual substances. Now the process of creating new promising materials with special mechanical, thermal, electrical and magnetic properties is in full swing. Although the work aimed at obtaining new active substances and other materials may be fundamentally different from each other, in any case, it is difficult to disagree with the fact that research in all these areas is becoming more focused and is carried out more on the basis of inference and less often on empirical way. Knowledge of the relationship between structure and action, and between structure and properties, increasingly allows solving problems at the molecular level. With the support of effective analytics, such developments can solve many problems while taking into account all the necessary aspects - usability, compatibility with the environment and saving resources. The use of balances in chemical experiments, which we owe to A.L. Lavoisier (1743-1794) marked the beginning of the era of so-called modern chemistry. R.V. Bunsen (1811–1899) and R. Fresenius (1818–1897) are considered the founders of analytical chemistry in Germany. Bunsen already in the middle of the 19th century carried out fundamental research on the chemical processes taking place in blast furnaces. One of the remarkable results of his activity was the possibility of a noticeable reduction in specific fuel consumption. Prof. Fresenius opened a private teaching laboratory in Wiesbaden in 1848, bringing together research, teaching and application 1.1 under one roof. Historical reference 25 th chemistry. The active work of this institution was primarily focused on water analysis, the study of technical products and minerals, the determination of the quality of sugar and alcohol, the detection of inorganic components in plants, the analysis of soils and fertilizers, and the study of atmospheric air. W. Ostwald (1853–1932) in 1894 published a book in Leipzig entitled "The Scientific Foundations of Analytical Chemistry", thereby abandoning the then customary idea of ​​analytical chemistry as some kind of auxiliary subject. For his fundamental work on the study of catalysis, Ostwald received in 1909 the Nobel Prize in Chemistry. This was followed by the achievements of Van't Hoff (1852–1911), Z.A. Arrhenius (Nobel Prize in Chemistry in 1903) and V.G. Nernst (Nobel Prize in Chemistry in 1920). This classical era of analytical chemistry proceeded predominantly under the sign of chemical reactions combined to achieve analytical separation, which basically proved to be excellent in applied analytics for many decades. The discovery of new chemical elements was a powerful impetus for creativity among chemists, and the development of each new method of analysis entailed further discoveries. If the element germanium was discovered in 1886 by the chemical precipitation method already known by that time, then R. Bunsen, together with the physicist Kirchhoff (1824–1887), managed to develop the isolation of rubidium and cesium for alkali metals in mineral waters in 1861 with the help of emission spectral analysis. During chemical separation, the most important spectral lines of both metals were traced, and after each separation, the tracking of that part of them, where the lines turned out to be the most intense, continued. Later, on the basis of emission spectral analysis, the following were discovered: thallium (1861), indium (1863), gallium (1875). As another example, mention may be made of the development of radiochemical methods which led Madame Curie in 1898 to the discovery of radium and polonium. In 1911 Marie Curie received the Nobel Prize in Chemistry for the discovery of these elements, as well as for their description and investigation with indication of effective isolation. This was followed by the success of other scientists: in 1922, hafnium was found, and in 1925, rhenium was found as the last of the natural elements missing from the periodic system, and this was achieved precisely on the basis of the X-ray spectral analysis that had just been introduced into practice. With the flourishing of the chemical industry, this positive phase associated with the accumulation of new knowledge (the discovery of previously unknown elements, the creation of the theory of atoms, the theory of gases, the law of mass action, the study of stoichiometry, the process of nuclear fission, etc.) was superimposed and negative, where the scientific side of analytical chemistry was largely devalued. The latter was mainly used only for the standard control of synthesis products, in the course of which these products had to be decomposed again, involving additional funds. For the characterization of organic synthesis products, for quite a long time only the analysis of organic elements was proposed as the only analytical principle. This was developed by J. von Liebig in 1837, and later improved first by F. Pregl in the 1920s, then many other microanalysts joined this process. For the development of microanalysis of organic substances, Pregle received the Nobel Prize in Chemistry in 1923. If in Liebig's time samples weighing up to a gram were still used, now their weight has been reduced to a few milligrams. This not only made it possible to reduce the duration of analyzes, but also made it possible to carry out elemental analyzes of expensive natural compounds. Numerous attempts were made to reduce sample weights to the lower μg range, but these rather costly methods were later replaced by mass spectrometry. In general, the 1920s–1930s were the period of development of classical microanalysis. However, in qualitative analysis, preference was given to blowpipe and microcrystalline reactions, which were not only aesthetic in their way, but also extremely sensitive and more reliable than the previously popular color and drop reactions. However, in the 1950s–1960s, work on the development and improvement of techniques in microinvestigation methods began to curtail due to the very negative attitude of the public towards analytical chemistry as a whole that had developed by that time. In a much more favorable environment than was the case with the chemical industry, elemental analytics in geochemistry and metallurgy developed in the 1950s. Here, much earlier than in other industries, its indispensability was realized in optimizing the properties of products (for example, alloys and steels), as well as in obtaining new knowledge about the structure of the earth's crust, which accelerated the extraction of raw materials contained in the bowels of the Earth. A bet was made on the Bunsen spectral analysis with the involvement of many subsequent incentives that contribute to the development of modern instrumental analytics. However, despite the active introduction of physical methods of analysis, spectroscopy, which has already begun, chemical analytics to this day remains primarily that area of ​​chemistry, discoveries in which are often made, so to speak, “at the tip of a pen,” because only deep knowledge substances and materials can create a solid basis for proper analytical chemistry. 1.2. Advantages of instrumental analytics Direct instrumental techniques are mainly physical relative methods, where analytical measured quantities differ from the results in classical analytical chemistry (example: sediment mass), representing electrical parameters due, for example, to beams of electrons, photons, neutrons and ions. The desired concentration or, accordingly, the determined absolute amount of the element or compound thus becomes a function of the appropriate calibration of the equipment. Under the condition of correctly performed instrumentation calibration, the advantages of instrumental analytics consist, first, in the possibility of registering very small (trace) concentrations (up to the lower microrange), 1.2. Advantages of instrumental analytics 27, moreover, with the use of a relatively small amount of a substance, and, secondly, in the speed of analysis, which provides the prerequisites for process automation and multiple use of the same sample, since the substance under study does not undergo any changes during the analysis. 1.2.1. Trace analytics Error, % The methods of classical analytical chemistry, which give extremely accurate results up to a thousandth of a percent when determining the content, are based mainly on chemical reactions, including precipitation of sparingly soluble products (gravimetry) or intensely colored products (titrimetry) . Since the elements to be studied are in the form of ions in an aqueous solution, we can speak of "wet" methods of chemical analysis. These classic ultra-low volume methods are no longer suitable for cost-effective laboratory analytics in the trace range. If, for example, it is necessary to perform a quantitative determination of the concentration of an element of 1 ng/g in a cell, then a determination method with absolute detectability in the femtogram range (1 fg = 10–15 g) will already be required. It is clear that analytical information in this case should still be sufficiently reliable. The doubtfulness of the obtained data cannot be ruled out today at all phases of the analytical process, when it is necessary to determine negligibly small concentrations in units of ng/g and below. The reason for this state of affairs is the presence of systematic errors, which are of only minor importance in traditional analyzes, but their role sharply increases with the determination of ever lower content of elements. While the known statistical errors do not go beyond the laws of probability and, therefore, are mathematically well described (which makes it possible to reduce their number due to multiple repetitions of measurements), the sources of systematic errors are often complex in nature, and therefore are recognized with great difficulty and from they are not insured even by the most experienced spe Billionth shares Millionth shares Fig. 1.1. Increasing Unreliability of Trace Analysis Results with Determinations of Grades 28 Chapter 1. An Introduction to Trace Analysts. Thus, minimization of systematic errors has become the main problem of ultratrace analysis (Fig. 1.1). The maximum possible elimination of such errors requires a lot of experience and, above all, qualified criticality. Here, there is a trend towards the development of economical instrumental direct methods implemented using very expensive equipment and based on physical principles. Experts immediately adopted the modern term "instrumental analytics". From the point of view of the necessary costs, express direct methods of determination for use in standard analyzes, including those with real time control, play an important role. Manufacturers of related equipment offer a wide variety of measurement setups, from high-performance research setups to miniaturized on-site analysis devices. 1.2.2. High sample turnover Nowadays, the concept of "throughput", "efficiency" or "productivity" is becoming more and more popular. Increasing productivity is a sine qua non for the decent standard of living that a social system can offer its citizens. Therefore, private industrial enterprises and many public organizations are tirelessly looking for and finding new ways to improve the quality of goods and services. R&D equipment manufacturers have been among the most energetic in promoting productivity in the broadest sense of the word in recent decades. Let us recall at least what a typical analytical laboratory looked like before. It had a huge supply of glassware - various kinds of pipettes and burettes - and a myriad of highly qualified scientists who spent a full day at the laboratory table. But the result of their daily work was, to put it mildly, inadequate: an insignificant number of samples studied. At present, due to the use of modern highly efficient devices, the volume of work performed has increased dramatically. Many laboratories today analyze, typically, thousands of samples daily, and the additional information obtained from these efforts serves as the basis for subsequent studies. Minerals and oils are now detected much more efficiently, processed faster into end products, and waste is greatly reduced – all of which brings down costs! The quality factor of raw materials used in industry and end products has undoubtedly increased in recent years, so that the consumer can expect much better food, pharmaceuticals and durables than in past years. Quality assurance standards require highly effective analytical studies throughout the entire production process. Instead of the earlier customary sampling of random samples, now more and more often they are switching to checking each individual 1.3. Spectroscopy 29 of packaging – for example, as part of the control of the receipt of goods. In this regard, analytics must be prepared for the influx of an increasing volume of samples, and the processing of a greatly increased volume of material with the same (or even fewer) number of employees is possible only on the basis of automation and express methods of analysis. Since the bulk of the time usually falls on sample preparation, it is generally possible to speed up the work mainly by reducing the time for this operation or even completely eliminating it. Thus, we can talk about a trend towards the transition to measurement methods integrated into the process or operating in real time (Inline and, accordingly, Online). Imagine the huge volume of analyzes that must be performed at the present time in the framework of the protection of environmental objects. With manual methods from the past, there is simply nothing to do here! It is clear that without modern analytical equipment we could not control processes and manage the state of the surrounding world in which we live today so effectively. The processing of a large amount of material for current analyzes can now be shifted to the shoulders of machines and automatons. Efficient automatic analytical devices are usually less expensive than manual instruments for classical analyses. In this case, the machines give results that are not burdened by subjective assessment (for example, by the service personnel). Automatic equipment used in instrumental analytics can be roughly classified as follows: semi-automatic devices, in which part of the operations of the analysis itself is performed manually, fully automatic devices, which provide a fully automatic process for performing analyzes, logical automata - partially or fully automatic devices capable of Based on the measurement results, change (for example, optimize) the course of analysis, automatic process control - systems that provide further processing of the results of analysis in a microcomputer (for example, when controlling dosing pumps). There is a growing demand for ever faster, more flexible automated sample preparation and processing systems. The devices themselves - due to the equipment of their computers and in the presence of microprocessor control - need less and less maintenance personnel. To avoid errors and inaccuracies, the equipment is equipped with an automatic results control system that issues an error message if the measurements go beyond the tolerance field. 1.3. Spectroscopy Much of the knowledge about the structure of matter comes from experiments in which light—or, as we usually say, radiation—and matter enter into a certain interaction. Since the first practical analysis by Bunsen and Kirchhoff, spectroscopy, based on the interaction between radiation and matter, with its vast variety of methods, has become an essential aid to modern analytics. This can be explained both by progress in the field of improving equipment, and by fundamental theoretical works, the success of which would not have been possible without knowledge in the field of quantum mechanics that opens up new paths. It is known that light has a dual nature – wave and corpuscular, and two types of characteristics are used to describe it: wave and quantum. Some physical phenomena caused by the interaction of light and matter can be described using the wave nature of light, others only on the basis of the corpuscular theory. Visible light is an example of electromagnetic radiation. Other examples include: x-rays, ultraviolet radiation and infrared radiation. All these types of radiation have something in common: they can be registered as electromagnetic waves propagating at the speed of light and differing only in frequency. The development of classical spectroscopy and the application of absolutely new principles in spectral analytics have become the main reasons for the increasing role of spectroscopy in our time. It has such powerful information capabilities that we can safely say that modern atomic and molecular spectrometry is able to answer almost any meaningful question from the field of analytics. Even 30 years ago, the spectra of UV radiation and Raman scattering of light were recorded using photographic plates, and the spectra of IR radiation were recorded point by point with a galvanometer, and analog computing amplifiers equipped with tubes were considered the pinnacle of design thought, and spectrograms were compiled by mechanical sorting of punched cards. The essence of any quality control is a matter of identity. For the practical work of a control laboratory, measurement and technical methods are required that provide quantized and reproducible parameters. A certain measurement technique can always display only a part of all the properties of a product and ideally should selectively register features that indicate a particular quality. A simple measurement includes the determination of melting and boiling points, refractive index or viscosity. When it comes to chemical differences, the selectivity of such methods is clearly insufficient. On the other hand, chemical analyzes carried out by the known "wet method" are often too time-consuming, especially if quantitative data are to be obtained. So, remember: spectroscopy is the science of the interaction between light and matter. The introduction of spectroscopy into the field of analytics served as a powerful stimulus for its development and improvement. One dimensional methods of analysis provide only one measurable quantity for each substance (melting temperature, delay time, etc.). The spectroscopy methods are as mini 1.3. Spectroscopy 31 mum are two-dimensional methods of analysis that give at least one intensity value for a substance in each resolvable range of wavelengths (or masses) of the spectrum. Therefore, the information content of spectroscopy is large enough to answer almost any question from the field of analytics. This, in fact, is one of the reasons for the successful development of spectroscopic methods of analysis. Spectroscopy, by definition, deals with the description of atoms, ions, radicals, and molecules based on the registration and interpretation of their spectra obtained using various measuring devices, among which are: atomic absorption spectrometer, atomic emission spectrometer, or spectrophotometer. Spectroscopic instruments usually consist of three main components: a radiation source, a device for spectral decomposition, and a detector for measuring radiation. Practical spectroscopy very soon began to develop in two directions, dividing into atomic and molecular. Analytical techniques used for this purpose transitions in the schemes of energy levels of molecules and atoms with radiation quanta (photons) from parts of the spectrum from X-rays to ultrashort waves. In atomic spectroscopy, we are talking about the qualitative and quantitative determination of elements in different substances and concentration ranges. These include, for example, atomic absorption, atomic emission and X-ray fluorescence methods. Methods of molecular spectroscopy based on UV/visible, IR spectral regions, Raman scattering and NMR (nuclear magnetic resonance) make it possible to draw a conclusion about the bonds and structure of molecules. Characteristic bands or combinations of bands in a spectrum can be indicative of a particular quality, as well as the basis for identifying individual components. The general concept of "spectroscopy" also includes the methods of mass spectrometry and electron spectrometry. Although, strictly speaking, mass spectrometry is not a method based on the interaction between electromagnetic radiation and matter, but a separation method. The variety of proposed methods allows you to get answers to very specific questions, for which you can use: micro and trace analysis, surface analysis, the study of the fine structure of complex systems and reactive systems analytics. Many spectroscopic methods operate non-destructively, i.e., without destroying the sample, which makes it possible to repeatedly and differently study the same sample, which, even after that, may still be suitable for further study. This is especially convenient, for example, in the case of the analysis of works of art or in the final quality control of finished products. However, it is especially important that many spectroscopic methods can be implemented directly at the location of the sample to be studied, and the result of the analysis is given in real time, which makes it possible to timely intervene in the process, making the required adjustments, or to interrupt the work altogether. connection with an emergency, etc. Today it seems superfluous to talk about the importance of physicochemical methods of analysis, which have become the daily routine of every modern chi Chapter 1. Introduction 32 mycoanalytical laboratories. With the help of spectroscopic methods, it is possible to solve, in particular, the following tasks: find and extract raw materials, develop new products and technologies, design and optimize production processes, and ensure the required quality of manufactured products. Due to the versatility of applications, the high accuracy of the results and the remarkable sensitivity of detection, not to mention the significant reduction in the time for analysis, spectroscopic methods have reached the highest degree of economic efficiency. Today, without them, not a single ton of steel can be produced, not a single electronic unit can be created. There are statutory requirements for the quality of foodstuffs, as well as for vital substances such as water and air, and, finally, for drugs of various kinds, and these requirements must be strictly observed. With the help of spectroscopic methods, it is also possible to control the by-products of human activity: garbage, exhaust air and sewage. The study of economic foundations in a broad sense, from biochemistry to astronomy, is unthinkable without modern spectroscopic methods of analysis. Currently, in the field of instrumental analytics, computers are increasingly being used, due to which the equipment itself becomes more convenient and easier to maintain, and the processing of results is possible in any form. Under these conditions, in principle, it is enough for the operator to have only a general idea of ​​the essence of the analysis, and sometimes he may know nothing about it at all. However, one should not forget (and here lies the main danger!) that the reliability of a particular instrument always depends on the accuracy of its calibration, and, therefore, it is necessary to constantly and scrupulously check the results obtained. An analytical device should not become a kind of “black box”, and the calculated indicators should never be blindly trusted by a computer, since it can only process the results of the analysis performed. But the “correct” analysis largely depends on the thoroughness of sampling, their preparation, and the provision of appropriate working conditions. Almost all instruments used in spectroscopy contain, often in modular design, systems for sampling and excitation of an analytical signal. Next, the spectrometer comes into action to create a spectrum in the wavelength range of interest and isolate a signal specific for a given substance; then comes the turn of the detector system to register the measurement signal, and finally, the device for processing the measurement data takes over. An important role is also assigned to the control system for all measurement processes with the support of computers. In recent years, personal computers have become especially popular in this area. Along with the introduction of high performance PCs, the development of many new methods of analysis was effectively promoted by the emergence of such structural components as laser radiation sources and optical fibers. 1.4. “Nothing”: how to find it 33 Today, many time-consuming operations (taking samples, preparing them, placing them in a device) are automated, and light fibers make it possible to study samples that are outside the spectrometer or belong to a dangerous, sensitive or highly valuable material . It is expected that in the future many of the analyzes performed today by the Liebig method (taking samples, transporting them to the laboratory, performing the actual analysis, processing the results) will be carried out in real time right at the workplace, either using miniature specialized spectrometers or optical waveguides connecting different sampling points to the central spectrometer. The purpose of this publication is to discuss the problems of spectroscopy, but this book should not be considered as a manual for the spectroscopist. It is addressed, first of all, to practical chemists and engineers employed in industrial production, who use spectroscopic studies as an auxiliary tool in solving various kinds of chemical problems. The above introduction is intended to give an overview of the existing spectroscopic methods and to encourage the named target group to apply these methods more actively in their own work. 1.4. "Nothing": how to find it It is clear that the distance from Stuttgart to Red Square in Moscow cannot be covered in two jumps: an air line 2000 km long stretched between them. Two millimeters of this path is 1 ppb (parts in a billion), which corresponds to one billionth of the entire path. Already in this case - in the presence of the number "only" with nine zeros - there is a limit to human imagination. A person's ability to imagine a certain size or number is more related to his daily life: everyone understands, for example, what is the weight of one kilogram. It will not be difficult for any person to show with his hands an approximate length of one meter. And anyone knows how long one hour lasts, especially if it has to be spent in agonizing expectation. But at the mention of a thousand tons, a hundredth of a millimeter and 4000 years, a person already feels the limit beyond which his imagination is powerless, and even the number of light years, the number of nanos kunds and parts per billion will make his mind completely capitulate. In the old days, only natural scientists operated with such rare units of measurement. But now this designation can be found in all media when reporting, say, the power of a power plant (megawatts), the discovery of a new hormone (micrograms) or the pollution of groundwater (parts per billion). Modern analytics is engaged in, so to speak, "the world after the decimal point." Over the past two decades, no science has achieved such impressive success as analytics - the science of detecting substances and determining their concentrations. If more than 40 years ago, the amount of any substance up to a tenth of a ppm had to be considered equal to "zero", today we can quite detect only one billionth of a gram. Thus, this science is able to quantify at the level of traces, which is absolutely beyond the human imagination, and this success has given a whole new dimension, in particular, to the discussion of environmental problems. In practice, one can already try to discover something that was previously designated as "nothing". This also applies to the trace residues mentioned above in soil, water, air and, finally, in food. Strictly speaking, there is no “zero balance” at all, but analytics also reveals traces of some traces. Zero thus remains a theoretical value that can be approached but never reached. Figure 1.2 clearly demonstrates the concentration values ​​at the ultra trace level. The purest substance that can be made today is silicon. Even when using the zone melting method, it is possible at best to obtain a purity of the order of 109 impurity atoms per cm3. Simplified as 1023 atoms per cm3, this corresponds to a contamination of about 1014 atoms, or 0.01 ppt (parts per trillion). Example: the content of one lump of sugar (2.7 g) dissolved in: 1 percent is 1 part in 100 parts 1 ppb (part per billion) is 1 part in 1 billion parts (billionth) 10 grams per kilogram 1 microgram per kilogram 0.27 liters 2.7 million liters 10 g/kg 0.000 001 g/kg 1 ppm is 1 part in 1000 parts 1 ppt (part per trillion) is 1 part in 1 trillion parts (trillion) 1 gram per kilogram 2, 7 liters 1 g/kg 1 nanogram per kilogram 0.000 000 001 g/kg 1 ppm (part per million) 1 ppq (part per quadrillion) is 1 part out of 1 quadrillion parts (quadrillion share) 1 milligram per kilogram 1 picogram per kilogram 0.000 000 000 001 g/kg 0.001 g/kg Pond 2700 liters Fig. 1.2. Illustrative examples of concentration values ​​of 2.7 billion liters Lake of 2.7 trillion liters 1.4. "Nothing": How to find it 35 But the high performance of analytics has its own pitfalls: again and again one has to deal with situations where erroneous conclusions are drawn from the results of the analysis, since handling "tiny" sizes requires strict adherence to many boundary conditions. We are all, in a sense, hostages of analytics, leaving the question unanswered: what concentration of a “suspicious” substance is still considered dangerous? This is where science simply confuses us. Politicians evade the answer, the increased sensitivity of detection methods excites the public. Thanks to the extreme sensitivity of modern analytics, we can detect many more substances in the soil, in the water, in the air, and in our food, and among them will be those that we did not even suspect before, because we did not have the necessary equipment. Many of these substances are present only as subtle traces, well below their toxicity threshold. In addition, for most trace concentrations, we know nothing about toxicological or environmental relevance, which means that the evaluation of the results clearly lags behind the progress in trace analytics itself. Also, when discussing environmental loads, terms such as ppm (parts per million), ppb (parts per billion), ppt (parts per trillion), and more recently even ppq (parts quadrillion) are increasingly used, in the absence of a clear ideas about the actual volume of “pollution” indicated by such units or about the quality factor of the obtained analysis results. It is perhaps difficult to find illustrative examples for such quantities. However, one part per thousand others, that is, ppm, is still familiar to us - first of all, from the experience of checking the alcohol content in the blood of car drivers. As for ppm, here one can jokingly imagine one inhabitant of Prussia (Prussian) in the millionth city of Munich, that is, 1 P(reuse) p(ro) M(ünchen) - “one Prussian per Munich”, but with ppb it’s the situation is much more complicated, since this unit will mean 5 people for the entire population of the globe, if taken as 5 billion. The next (downward) size - ppt - could demonstrate the fact that 100,000 tons of wheat in a freight train 20 km long were contaminated by a single grain of rye or - in terms of a measure of length - display a "segment" of 0.4 millimeters on the way from the Earth to the moon. ... It is hardly worth continuing. Further, any attempt to give a clear example will simply fail. With such orders of magnitude, no one is surprised that at the present time certain substances are found even where no one expected it. People hear and read about such “finds” again and again, but this does not mean that the substances found now were not here before, it was just that they could not be found before. This nuance often remains outside the scope of public discussions. Decisions about harm or benefit, about the degree of danger, about the need to develop adequate measures are not made on the basis of the fact that a substance is found at all. To a much greater extent, it depends on the measured volume of a given substance and on the degree of probability of our contact with it. Only the dose that a person actually absorbs matters when considering the effect on his body of a particular material. More on 36 Chapter 1. Introduction almost 500 years ago, doctor T.B. von Hohenheim, known by the name of Paracelsus, stated: "Nothing absorbed in excess is absolutely harmless." However, irony aside, it is precisely the ultra-precise measurements in modern chemical analytics that are now being used as a weapon against chemistry itself and its so-called poisons. And yet, analytics, with its modern technical equipment, has managed to provide scientists with approaches to those areas that for a long time remained out of their reach. Suffice it to mention at least the significance of "trace elements" in our daily life. In too high a concentration, they act as toxins, in a precisely verified amount they are sometimes even recognized as useful, and if they are deficient, they can cause a deficiency syndrome. Reliable results require the most careful preparation and correct analysis, which is especially true for measurements of traces of certain substances. These requirements concern not only the process of taking samples, their storage and preparation, but also the equipment of the laboratory, the qualifications (and behavior) of personnel performing certain operations. If, for example, you allow yourself to smoke in the laboratory, then you should not be surprised to find an increased content of cadmium in the test substance; an attempt to measure less than a milligram per liter of carbon on a waxed laboratory table is understandably doomed to failure, and what can we say about determining traces of metal in water samples taken with a metal bucket! Even more problematic is the situation when it is absolutely unreasonable to believe that the effect of trace substances correlates with their concentration. This is probably due to the fact that since the time of Newton and Descartes we have been accustomed to generalize and extrapolate on the basis of our usual linear idea of ​​the inseparability of cause and effect. Today we have to abandon outdated ways of thinking, including in the material sphere. Extrapolations and generalizations, which are quite appropriate when determining sufficiently high concentrations, turn out to be absolutely inadmissible in the case of a very low content of a substance. We will have to learn to think more layered and complex. Increasingly, we are forced, along with such convenient “either or” solutions, to allow solutions at the level of “both … and …” if we want to correspond to the realities of our complex world. The concepts of “right” and “wrong” can be unambiguously applied, perhaps, only in the field of qualitative analytics. However, from the point of view of quantitative analytics, these definitions are generally unacceptable in some areas. Usually, a quantitative analysis is considered correct if it can be reproduced within the range of statistically established margins of error. And at the same time, the fact that the result obtained can turn out to be hopelessly erroneous no longer plays any role at all. This means that in the field of quantitative analysis, to the concepts of "correctness" and "incorrectness" one has to add a third concept - comparability, or comparability, of results. Quantitative analysis is considered correct if, in the area of ​​a given statistical significance, the same results of analysis are obtained from time to time. Calibration standards for instruments are generally carefully reviewed and followed 1.4. "Nothing": how to find it 37 reaping the measure of all things. But if another standard does not fit, analysts are forced to find comparable parameters. Therefore, the analysis is classified as "correct" because no analyst works according to a different methodology and different standards. This means that the opportunities to get correct, incorrect or comparable results in the field of quantitative analytics are sometimes established simply by a volitional decision. 1.4.1. Example: Platinum Of the many examples that clearly demonstrate the need for broader analytical thinking, here we can mention the not so common situation that the introduction of platinum catalysts has thrown us into. Platinum catalysts contribute significantly to the reduction of nitrogen oxide and hydrocarbon emissions. For this purpose, about 50 tons of platinum metals are processed annually. True, in a small volume, platinum is still released and accumulates in the environment, because even under the operating conditions of a catalyst, it cannot behave absolutely indifferently. With the three way catalysts we use, the volumes of released platinum reach only the average nanogram range per kilometer of movement. However, these so meager volumes noticeably increase over time due to gradual accumulation. At the current level of knowledge, it is still impossible to state with certainty the probability of the onset of certain physiological consequences for the human body as a result of exposure to this released platinum. In this case, we can talk about platinum asthma, platinum disease, cancer, but we repeat: it is necessary to carefully study the nature of the distribution and the type of relationship of platinum as the most important risk assessment criteria. Since the natural and inherent concentration of platinum in the blood is about 10–9%, the necessary methods for determining the volume in units of picograms still need to be carefully developed. Nevertheless, even today it is possible to reliably establish such low concentrations of platinum in the human body and in substances important for the environment. People in direct contact