Spectroscopy of Low Temperature Plasma......Page 3
Contents......Page 9
Preface......Page 19
References......Page 22
1.1 The Concept of Low-Temperature Plasma. Diagnostics Problems......Page 25
1.2.1 Energy Distribution of Particles......Page 30
1.2.2 Law of Mass Action. Neutral and Charged Particle Densities......Page 31
1.2.3 Heat Emission. Kirchhoffβs Law......Page 35
1.3.1 Local Thermal Equilibrium (LTE) Model......Page 38
1.3.2 Partial Local Thermal Equilibrium (PLTE) Model......Page 40
1.3.3 Model of Coronal Equilibrium (MCE)......Page 44
1.3.4 Collisional-Radiative Model (CRM)......Page 45
1.4 Optical Spectrum and Plasma Parameters......Page 46
References......Page 49
2.1 Photometric Quantities. Remarks on Terminology......Page 51
2.2 Spectral Line Profile......Page 55
2.2.1 Lorentz Broadening......Page 56
2.2.2 Doppler Broadening......Page 62
2.2.3 Joint Action of Natural, Doppler and Collision Broadening......Page 65
2.3 Absorption in Lines......Page 68
2.4 Emission in Lines. Optical Density Manifestations......Page 70
2.5 Emission and Absorption in Continuous Spectrum......Page 74
2.5.1 ff Bremsstrahlung Emission......Page 76
2.5.2 ff Bremsstrahlung Absorption......Page 78
2.5.3 fb Recombination Emission......Page 79
2.5.4 Absorption Cross Section in bf Photoionization......Page 81
2.5.5 Emission and Absorption of Radiation in the Case of Joint Action of the ff Bremsstrahlung and fb Recombination Mechanisms......Page 82
2.6.1 Thomson Scattering on a Free Electron......Page 84
References......Page 87
3.1.1 Identification of Spectra......Page 91
3.1.2 Absolute Measurements......Page 92
3.1.3 Emission of Extended Inhomogeneous Sources......Page 95
3.2.1 Absorption Against the Background of Continuous Spectrum......Page 99
3.2.2 Line Absorption......Page 102
3.2.3 Self-Absorption of Multiplet Lines......Page 107
3.3.1 On the Advantages of Laser Sources Over Their Classical Counterparts in Direct Absorption Measurements......Page 108
3.3.2 On the Noise Limitation of Sensitivity......Page 110
3.3.3 Diode Laser Spectroscopy in the IR Region......Page 112
3.3.4 Nonstationary Coherent Effects in Absorption Measurements......Page 116
3.3.6 Intracavity Absorption......Page 119
3.3.7 Measuring Absorption from the Attenuation of Light with Time......Page 123
3.4 Indirect Methods for Measuring Absorption of Laser Light......Page 127
3.4.1.1 General Characteristic......Page 128
3.4.1.2 Fluorescence Excitation by Continuous-Wave and Pulsed Laser Light......Page 131
3.4.1.3 Induced Fluorescence Saturation and Decay......Page 133
3.4.1.4 Induced Fluorescence Quenching and Taking Account of this Process......Page 136
3.4.1.5 Restrictions Imposed by the Plasmaβs Own Glow......Page 142
3.4.2.1 The Use of the Optogalvanic Effect to Measure Light Absorption in Plasma......Page 145
3.4.2.2 High-Resolution Optogalvanic Spectroscopy......Page 148
3.5 Multiphoton Processes. Raman Scattering......Page 153
3.5.1 Two-Photon Absorption......Page 154
3.5.2 Spontaneous Raman Scattering......Page 157
3.5.3 Stimulated Raman Scattering......Page 159
3.5.4 Coherent Anti-Stokes Scattering......Page 161
References......Page 167
4.1 Doppler Broadening, Velocity Distribution of Particles, Neutral Gas Temperature......Page 171
4.1.1.1 Registered and True Profiles......Page 172
4.1.1.2 Predominantly Doppler Broadening Regions......Page 173
4.1.1.3 Recovery of the Form of the Velocity Distribution of Particles......Page 174
4.1.2 Examples of Abnormal Doppler Broadening and Nonequilibrium Velocity Distributions of Neutral Particles in Plasma......Page 175
4.1.3.1 Source Function......Page 178
4.1.3.2 Relaxation of the Average Kinetic Energy of Particles with a Finite Lifetime......Page 179
4.1.3.3 Relaxation of the Form of the Velocity Distributions of Particles in the Case of Large Deviations from Equilibrium and Finite Lifetime......Page 183
4.1.4 On the Determination of the Gas Temperature from the Doppler Broadening of the Lines Emitted by Atoms and Molecules Excited by Electrons......Page 185
4.1.5 Spectroscopic Manifestations of the Motion of Ions in Plasma......Page 188
4.2.1 On the Isolation of the Boltzmann Ensembles in the Bound State System of Particles......Page 191
4.2.2 Distributions of Molecules Among Rotational Levels in an Electronic State with a Long Lifetime......Page 194
4.2.3.1 Observations and General Considerations......Page 198
4.2.3.2 Experimental Determination of the Electron-Impact-Induced Changes in the Rotational States of Molecules in Plasma......Page 201
4.2.4.1 OH Radical. Violet Bands......Page 205
4.2.4.2 N(2) Molecules. Second Positive System......Page 207
4.2.5 On Gas Temperature Measurements in the Presence of Parallel Molecular Rotation Excitation Channels......Page 208
4.2.5.2 Spectral Resolution......Page 209
4.2.5.3 Effect of the Conditions Occuring in Plasma on the Rotational Temperature of the Hot Group......Page 212
4.3.1 Elements of Vibrational Kinetics. Vibrational Energy and Temperature......Page 215
4.3.1.1 Harmonic Oscillator Approximation......Page 216
4.3.1.2 Effect of Anharmonicity......Page 218
4.3.1.3 Diatomic Molecular Mixture and Polyatomic Molecules......Page 221
4.3.2 Vibrational Temperature and Distribution Measurements by Absorption Spectroscopy Techniques......Page 223
4.3.3 Emission Methods in the IR Region of the Spectrum......Page 230
4.3.4 Combinations of Emission and Absorption Techniques. Spectrum Inversion......Page 235
4.3.5 Raman Scattering......Page 240
4.3.6 Determination of the Vibrational Temperatures of Molecules in the Electronic Ground States from Electronic Transition Spectra......Page 244
4.4 Distribution of Particles Among Electronic Levels......Page 248
References......Page 252
5.1 General......Page 259
5.2.1 Neutral Unexcited Atoms......Page 261
5.2.2 Metastable Atoms......Page 273
5.2.3 Low-Multiplicity Positive Ions......Page 290
5.3 Determination of Molecular Concentration by the Absorption Method......Page 292
5.3.1 Probabilities of Optical Transitions in Diatomic Molecules......Page 293
5.3.2 Determination of Diatomic Molecular Concentrations from Absorption on Electronic Spectrum Lines......Page 296
5.3.3 Determination of Molecular Concentration from Absorption in Vibrational–Rotational Spectra......Page 302
5.3.5 Absorption of IR Radiation by Polyatomic Molecules......Page 305
5.3.6 Absorption of Radiation by Molecular Ions......Page 308
5.4 Actinometric Methods......Page 312
5.5 Negative Ions......Page 321
5.5.1 Concentration Measurements......Page 322
5.5.2 Absorption of Light by the H(–) Ions in Hydrogen LTE Plasma......Page 325
References......Page 327
6 Spectral Methods of Determining Electronic and Magnetic Fields in Plasma......Page 331
6.1.1 Hydrogen-Like Atoms......Page 336
6.1.2 Non-Hydrogen-Like Atoms......Page 342
6.2 Laser Stark Spectroscopy......Page 346
6.2.1 Stark Spectroscopy of Atoms......Page 347
6.2.2 Laser-Induced Fluorescence of Polar Molecules in Electric Field......Page 353
6.2.3 Multiphoton Excitation of Atoms......Page 358
6.2.4 Coherent Four-Wave Stark Scattering Spectroscopy......Page 361
6.3.1 Measurements Based on the Faraday Effect......Page 366
6.3.2 Spectral Methods......Page 367
References......Page 370
7.1 Interferometry......Page 375
7.2.1 General......Page 380
7.2.2 Plasma Microfields......Page 381
7.2.3 Linear Stark Effect......Page 382
7.2.4 Quadratic Stark Effect......Page 388
7.3 Truncation of Spectral Series of Hydrogen-Like Atoms......Page 391
7.4 Intensities in Continuous Spectrum......Page 395
7.5 Scattering of Light on Electrons......Page 398
7.5.1 Scattering of Light by Randomly Moving Electrons (Thomson Scattering)......Page 399
7.5.2 Manifestation Regions of the Thomson and Collective Scattering Mechanisms......Page 401
7.5.3 Scattered Spectrum and Plasma Parameters (Direct Problem)......Page 403
7.5.4 Determination of Plasma Parameters from Scattered Spectra (Inverse Problem)......Page 405
7.5.5 Limitations of the Method, Sensitivity and Examples......Page 409
7.6 Some Remarks on Measurements from Intensities in Line and Band Spectra......Page 415
References......Page 418
8 Some Information on Spectroscopy Techniques......Page 421
8.1.1 Reflection at an Interface......Page 422
8.1.2 Dispersion of the Optical Properties of Materials......Page 423
8.1.3.1 Metal Films......Page 424
8.1.3.2 Dielectric Films......Page 426
8.2 Spectral Instruments......Page 430
8.2.1 Slit Instruments......Page 433
8.2.2 Interferometers......Page 438
8.2.3.1 Fourier(-Transform) Spectrometers......Page 449
8.2.3.2 Interference Spectrometers with Selective Amplitude Modulation (ISSAM)......Page 454
8.2.4 Raster Spectrometers......Page 455
8.2.5 Acousto-optic Spectrometers......Page 457
8.3.1 Illumination Engineering Quantities......Page 463
8.3.2.1 Continuous-Discharge Lamps......Page 465
8.3.2.2 Pulsed-Discharge Lamps......Page 472
8.3.3.2 Pulsed-Discharge Sources......Page 480
8.4 Photodetectors......Page 484
8.4.1.1 Sensitivity......Page 485
8.4.1.2 Noise......Page 486
8.4.1.3 Effective and Ultimate Sensitivity......Page 487
8.4.2.1 Thermal Detectors......Page 488
8.4.2.2 Photoelectric (Quantum, Photonic) Detectors with Extrinsic Photoeffect......Page 490
8.4.2.3 Photoelectric Detectors with Intrinsic Photoeffect......Page 494
8.4.2.4 Photoemulsion......Page 495
8.4.2.5 Comparative Characteristics of Single-Element Detectors......Page 497
8.4.3.1 Spatial Resolution......Page 501
8.4.3.2 Photographic Detectors......Page 502
8.4.3.3 Image Converter and Intensifier Tubes......Page 503
8.4.3.4 Charge-Coupled Detectors......Page 504
References......Page 508
A.1 Statistical Weight of Energy Levels in Atoms and Ions......Page 511
A.3 Statistical Weight of Vibrational Levels of Molecules......Page 512
A.4 Statistical Weight of Rotational Levels of Molecules......Page 513
References......Page 519
References......Page 521
Appendix C Two-Photon Absorption Cross Sections for Some Atoms and Molecules in the Ground State......Page 523
References......Page 527
D.1 Brief Information from Molecular Spectroscopy – Designations of States and Transitions, Coupling Types, Selection Rules, General Spectrum Structure......Page 529
D.2 Nitrogen N(2), N(2)(+)......Page 537
D.3 Carbon Oxide CO......Page 550
D.4 Hydrogen H(2) and Deuterium D(2)......Page 552
D.5 Nitrogen Oxide NO......Page 565
D.6 Cyanogen CN......Page 567
D.7 Carbon Radical C(2)......Page 572
D.8 CH Radical......Page 575
D.9 Hydroxyl Radical OH......Page 582
References......Page 590
Appendix E Rotational Line Intensity Factors in the Electronic–Vibrational Transition Spectra of Diatomic Molecules......Page 593
E.2 Doublet Transitions......Page 594
E.3 Triplet Transitions......Page 597
E.4 Remarks on the Normalization of Rotational Line Intensity Factors......Page 604
E.5 On Symbolic Notation......Page 605
References......Page 606
Appendix F Measurement of the Absolute Populations of Excited Atoms by Classical Spectroscopy Techniques......Page 607
References......Page 619
G.1 Physical Constants......Page 621
G.3 Correspondence between Spectral and Traditional Energy Measurement Units......Page 622
G.5 Units from Molecular Kinetics......Page 623
G.6 Quantities from Gas-Discharge Physics......Page 624
References......Page 625
Index......Page 627