Gas phase molecular spectroscopy is a powerful tool for obtaining information on the geometry and internal structure of isolated molecules as well as on the interactions that they undergo. It enables the study of fundamental parameters and processes and is also used for the sounding of gas media through optical techniques. It has been facing always renewed challenges, due to the considerable improvement of experimental techniques and the increasing demand for accuracy and scope of remote sensing applications. In practice, the radiating molecule is usually not isolated but diluted in a mixture at significant total pressure. The collisions among the molecules composing the gas can have a large influence on the spectral shape, affecting all wavelength regions through various mechanisms. These must be taken into account for the correct analysis and prediction of the resulting spectra. This book reviews our current experimental and theoretical knowledge and the practical consequences of collisional effects on molecular spectral shapes in neutral gases. General expressions are first given. They are formal of difficult use for practical calculations often but enable discussion of the approximations leading to simplified situations. The first case examined is that of isolated transitions, with the usual pressure broadening and shifting but also refined effects due to speed dependence and collision-induced velocity changes. Collisional line-mixing, which invalidates the notion of isolated transitions and has spectral consequences when lines are closely spaced, is then discussed within the impact approximation. Regions where the contributions of many distant lines overlap, such as troughs between transitions and band wings, are considered next. For a description of these far wings the finite duration of collisions and concomitant breakdown of the impact approximation must be taken into account. Finally, for long paths or elevated pressures, the dipole or polarizability induced by intermolecular interactions can make significant contributions. Specific models for the description of these collision induced absorption and light scattering processes are presented. The above mentioned topics are reviewed and discussed from a threefold point of view: the various models, the available data, and the consequences for applications including heat transfer, remote sensing and optical sounding. The extensive bibliography and discussion of some remaining problems complete the text. . State of the art on the subject. A bibliography of nearly 1000 references. Tools for practical calculations. Consequences for other scientific fields. Numerous illustrative examples. Fulfilling a need since there is no equivalent monograph on the subject
Author(s): Jean-Michel Hartmann, Christian Boulet, Daniel Robert
Publisher: Elsevier Science
Year: 2008
Language: English
Pages: 409
Tags: Физика;Практикумы, экспериментальная физика и физические методы исследования;
cover.jpg......Page 1
Dedication......Page 2
Foreword......Page 3
Acknowledgments......Page 4
Introduction......Page 5
Introduction......Page 12
General Formalism......Page 13
The Hamiltonian of the Molecular System......Page 16
General Properties of the Correlation Function......Page 19
The Binary Collision Approximation......Page 20
Initial Statistical Correlations......Page 22
The Impact Approximation......Page 23
Beyond the Impact Approximation......Page 26
Effects of the Radiator Translational Motion......Page 28
Collision-Induced Spectra......Page 31
Absorption, Emission, and Dispersion......Page 36
Rayleigh and Spontaneous Raman Scatterings......Page 38
Nonlinear Raman Spectroscopies......Page 41
Time-resolved Raman Spectroscopies......Page 45
The Large Number of Perturbers......Page 47
The Local Thermodynamic Equilibrium......Page 48
The Binary Collisions......Page 50
The (full) Impact Assumption......Page 52
Analysis through the time dependence......Page 53
Analysis through the frequency dependence......Page 57
The Liouville Space......Page 58
Spectral-Shape Expression......Page 61
Rotational Invariance......Page 63
Detailed Balance......Page 64
Introduction......Page 66
Doppler Broadening and Dicke Narrowing......Page 76
The Doppler Broadening......Page 77
The Dicke Narrowing......Page 78
The Lorentz Profile......Page 80
The Dicke Profile......Page 81
The Voigt Profile......Page 82
The Galatry Profile......Page 83
The Nelkin-Ghatak Profile......Page 84
Correlated Profiles......Page 86
Characteristics of the Basic Profiles......Page 88
Observation Of Speed-Dependent Inhomogeneous Profiles......Page 93
Basic Speed-Dependent Profiles......Page 101
The Rautian-Sobelman Model......Page 107
The Keilson-Storer Memory Model......Page 117
The Waldmann-Snider Kinetic Equation......Page 129
The Generalized Hess Method......Page 131
Collision Kernel Method......Page 133
Approaches From A Simplified Waldmann-Snider Equation......Page 136
Conclusion......Page 142
Algorithms for the Voigt and Galatry Profiles......Page 143
Computation of Speed-Dependent Profiles......Page 145
Introduction......Page 149
Approximations and General Expressions......Page 156
First-order Approximation......Page 160
Second-order Approximation......Page 163
Entire Bands......Page 164
Isolated Clusters of Lines......Page 166
Entire Bands......Page 168
Isolated Clusters of Lines......Page 170
Using the First-Order Expression......Page 171
Using the Full Relaxation Matrix Expression......Page 173
Constructing the Impact Relaxation Matrix......Page 175
Isotropic Raman Q branches......Page 176
Infrared and Anisotropic Raman Q branches......Page 178
Multi-branches Spectra......Page 179
The Ovaloid Sphere Model......Page 182
Introduction......Page 183
Q branches of Linear Molecules......Page 185
Other Species and Mutibranch Spectra......Page 189
Introduction......Page 190
Rovibrational Components of Linear Molecules......Page 194
Hyperfine Rotational Components of Linear Molecules......Page 199
Asymmetric-Top Molecules......Page 200
Introduction......Page 201
The Neilsen and Gordon Approach......Page 202
The Anderson, Tsao and Curnutte Approach......Page 205
The Robert and Bonamy Approach......Page 207
Applications to Line-Mixing Problems......Page 210
Introduction......Page 213
The Close-Coupling Approach......Page 214
The Coupled-States Approach......Page 215
The Infinite Order Sudden Approach......Page 217
Applications to Line-Mixing Problems......Page 218
Introduction......Page 220
Relaxation Matrix Elements......Page 224
First-Order Line-Coupling Coefficients......Page 226
Literature Review......Page 229
Available Line-Mixing Data......Page 230
Comparisons Between Predictions and Laboratory Measurements......Page 231
Conclusion......Page 234
Vibrational Dephasing......Page 235
Perturbed Wave Functions......Page 239
Resonance Broadening......Page 240
Introduction......Page 243
The chi Factor Approach......Page 245
The Tabulated Continua......Page 248
Far Wings Calculations: The Quasistatic Approach......Page 250
General Expressions......Page 251
Practical Implementation and Typical Results......Page 254
The Band Average Line Shape: Back to the chi Factors......Page 257
General Expressions......Page 259
Illustrative Results......Page 261
General Expression......Page 263
Illustrative Results......Page 265
Conclusion......Page 267
The Water Vapor Continuum......Page 268
Definition, Properties and Semi-Empirical Modeling of the H2O Continuum......Page 270
On the Origin of the Water Vapor Continua......Page 271
The Self- and N2-broadened Continua within the nu2 Band......Page 273
Conclusion......Page 274
Introduction......Page 276
Collision-Induced Dipoles and Polarizabilities for Diatomic Molecules......Page 277
Two Illustrative Examples: H2 AND N2......Page 278
Modeling of the Line Shape......Page 282
Effects of the Anisotropy of the Interaction Potential......Page 285
The Importance of Bound and Quasibound States in CIA Spectra......Page 291
Interference Between Permanent and Induced Dipoles (CIA) or Polarizabilities (CILS)......Page 294
Depolarized Light Scattering Spectra of H2 and N2......Page 295
The HD Problem......Page 297
Intercollisional DIPS......Page 301
Conclusion......Page 302
Introduction......Page 304
Radiative Heat Transfer......Page 305
Remote Sensing......Page 308
Radiative Heat Transfer......Page 312
Remote Sensing......Page 313
Remote Sensing......Page 315
Remote Sensing......Page 319
Radiative Heat Transfer......Page 326
Remote Sensing......Page 328
Radiative Heat Transfer......Page 332
Conclusion......Page 334
Models of Profiles in the Hard Collision Frame......Page 336
Experimental Tests in Multiplet Spectra......Page 340
From Resonances to the Far Wings......Page 344
Semi-Classical Approach......Page 345
Tomorrow’s Spectroscopic Databases......Page 349
Isolated Lines......Page 350
Line Mixing......Page 352
Far Wings......Page 353
Conclusion......Page 355
Abbreviations and Acronyms......Page 357
Symbols......Page 360
Units and Conversions......Page 362
References......Page 364
Subject Index......Page 407
