Molecular Spectroscopy Volume 5

290 Pages·1978·15.963 MB·English

A Specialist Periodical Report
~~
Molecular Spectroscopy
Volume 5
A Review of the Literature published
in 1975 and 1976
Senior Reporters
R. F. Barrow, Physical Chemistry Laboratory, Universify of Oxford
D. A. Long, School of Chemistry, University of Bradford
J. Sheridan, School of Physical and Molecular Sciences,
University College of North Wales, Bangor
Reporters
H. C. Andersen, Stanford University, Stanford, California, U,S.A.
J. E. D. Davies, University of Lancaster
B. S. Hudson, Stanford Universify, Stanford, California, U.S.A.
J. N. Macdonald, University College of North Wales, Bangor
B. Schrader, Universitat Essen, West Germany
S. D. Smith, Heriot- Watt University, Edinburgh
D. Steele, Royal Holloway College, Universify of London
The Chemical Society
Burlington House, London WIV OBN
ISBN: 0 85186 546 1
ISSN : 0305-9782
Library of Congress Catalog Card No. 72-92545
Copyright 0 1978
The Chemical Society
All Rights Reserved
No part of this book mdy be reproduced or transmitted
in any form or by dny means - graphic, electronic,
including photocopying, recording, taping or
information storage and retrieval systems - without
written permission from The Chemical Society
Printed in Great Britain by
Billing & Sons Limited, Guildford, London & Worcester
Fore word
_______~~___________ _______ _______ ~~ ~~ ________~ _____
This is the fifth volume in an annual series devoted to molecular spectroscopy. We
continue our wellestablished policy of selecting for detailed and critical reviews
those areas of molecular spectroscopy which we think are timely and interesting.
Several topics are reviewed for the first time in this series: coherent anti-Stokes
Raman spectroscopy (CARS); the application of spin-flip lasers to infrared
spectroscopy; vibrational spectroscopy of clathrates; and the infrared and Raman
spectroscopy of molecular crystals. Infrared intensities previously reviewed in
Volume 2 (1974) are treated again in this volume, and the annual coverage of
microwave spectroscopy is continued. Unfortunately a hoped-for contribution
relating to electronic spectroscopy has not materialized, but the subject will be
taken up again in the next volume.
Once again we thank our Reporters and the Editorial Staff of The Chemical
Society for their help in the preparation of this volume.
R. F. BARROW
D. A. LONG
June 1977 J. SHERIDAN

Contents
Chapter 1 Microwave Spectroscopy 1
By J. N. Macdunald and J. Sheridan
1 Introduction
2 Techniques
A. Single-radiation Methods
B. Multipleradiation Methods
C. Techniques for Chemical Analysis
3 Derivation of Molecular Information
4 Results for Individual Molecules
A. Molecules for which only One Stable Equilibrium
Configuration is Possible or Reasonable 8
(i) Diatomic Molecules 8
(ii) Linear Molecules 10
(iii) Non-linear Triatomic Molecules 13
(iv) Non-linear Tetra-atomic Molecules 15
(v) Non-linear Penta-atomic Molecules 18
(vi) Non-linear Molecules with More than Five atoms 22
B. Molecules with Large-amplitude Internal Motions But
with only Spectroscopically Equivalent Equilibrium
Nuclear Configurations 24
.
(i) Ammonia and its Simple Derivatives 24
(ii) Planar Molecules with Planar Symmetric Internal Tops 25
(iii) Molecules with Internal Rotation of one XY, Group
with respect to a Planar Frame, X lying in the Plane
of the Frame 26
(iv) Molecule with XY3 Group Attached to a Planar
Frame, X Lying Outside the Plane of the Frame 28
(v) Molecules with One XY3 group attached to a Non-
planar Frame 28
(vi) Molecules with Two or Three Equivalent Internal
Methyl Tops 29
C. Molecules for which More than One Non-equivalent
Equilibrium Nuclear Configuration is Possible 31
(i) Molecules with One Centre of Rotational Isomerism
and No Other Internal Rotations 31
(ii) Molecules with One Centre of Rotational Isomerism,
But also containing Symmetric XY3 Groups 36
(iii) Molecules with Two or More Centres of Rotational
Isomerism 39
vi Contents
D. Cyclic Molecules 41
(i) Three-membered Rings 41
(ii) Four-membered Rings 43
(iii) Five-membered Rings 43
(iv) Six-membered Rings 45
(v) Larger Rings 49
(vi) Fused-ring Structures 49
5 Microwave Spectroscopy in Astrophysical Chemistry 51
A. Newly Discovered Molecules 52
B. Interstellar Molecules and their Environment 52
C. Theoretical Developments 54
.
D Terrestrial Measurements 55
6 Collisions and Timedependent Effects 55
A. Collision Broadening and Pressure-induced Lineshifts 55
B. Steady-state Double-resonance Studies of Collisions 57
C. Transient Experiments 58
Chapter 2 infrared and Raman Spectroscopic Studies of Clathrate
inclusion Compounds 60
By J. E. D. Davies
1 Introduction 60
2 Clathrate Compounds 60
A. Quinol Clathrates 60
Introduction 60
Results and Discussion 64
(i) Monatomic guest species 64
(ii) Diatomic guest molecules 66
(iii) Triatomic guest molecules 69
(iv) Tetra-atomic guest molecules 71
(v) Penta-atomic guest molecules 71
(vi) Hexa-atomic and larger guest molecules 75
B. Clathrates of Dianin’s Compound 79
Introduction 79
Results and Discussion 80
C. Clathrate Hydrates 81
Introduction 81
Results and Discussion 82
3 Inclusion Compounds 83
A. Hofmann-type Compounds 83
(i) Benzene-containing Compounds 83
(ii) Pyridine-containing Compounds 88
(iii) Aniline-containing Compounds 89
(iv) Other Guest Molecules 92
(v) Compounds containing Ethylenediamine rather than
Ammonia 92
Contents vii
B. Compounds of Werner Complexes 93
Introduction 93
Results and Discussion 96
C. Urea and Thiourea Inclusion Compounds 100
Introduction 100
Results and Discussion 101
(i) Urea inclusion compounds 101
(ii) Thiourea inclusion compounds 102
4 Historical Note 105
Chapter 3 Infrared Intensities 106
By D. Sfeele
1 Introduction 106
2 Advances in Research Techniques 106
3 Theoretical Developments 114
4 Semi-empirical and ab initio Calculations 120
5 The Dipole Expansion 12 4
6 Other Experimental Studies 134
7 summary 140
Chapter 4 Coherent Anti-Stokes Raman Scattering 142
By H. C. Anderson and B. S. Hudson
1 Introduction 142
2 Macroscopic Theory of Linear and Cubic Optical Phenomena 148
A. Maxwell’s Equations and Constitutive Relations 148
B. Comments on the Meaning and Validity of the Macro-
scopic Maxwell Equations Theory 153
C. The Constitutive Relations for Harmonic Fields 154
D. Maxwell’s Equations for Harmonic Fields 158
E. Propagation of Light without Scattering 159
F. CARS 160
G. Spontaneous Raman Scattering 164
3 Molecular Theory of Third-order Susceptibility 168
A. Introduction 168
B. Perturbation Theory for the Molecular Susceptibility 169
4 Gas Phase CARS and Raman Spectroscopy 176
A. Raman Scattering 176
B. CARS 178
5 Liquid Phase CARS and Raman Spectroscopy 180
A. Introduction 180
B. Raman Spectroscopy 180
...
Vlll Contents
C. Non-resonant Background 182
D. CARS 183
E. Electronic Resonance Enhancement of Raman Scattering
and CARS 184
6 A Brief Review of CARS Experiments 186
A. Solid-phase Studies 186
B. Gas-phase Studies 187
C. CARS Spectra of Pure Liquids 188
D. CARS Spectra of Solutions 188
7 Experimental Aspects of CARS Spectroscopy 190
A. Experimental Apparatus 190
B. Noise Reduction 193
C. Phase Matching and Optimum Focusing 1 94
D. Spectral Analysis 195
E. Spectral Lineshapes for Resonance-enhanced CARS 197
F. Background Reduction in Four-wave Mixing Experiments 199
G. Two-photon Spectroscopy via Three- and Four-wave
Mixing 200
8 Future Prospects for CARS 201
Chapter 5 Infrared Spectroscopy with the Spin-flip Laser 202
By S. D. Smith
1 Introduction 202
2 Stimulated Spin-flip Raman Scattering 204
3 Experimental Arrangements 207
4 PulsedSpectra 21 5
5 Continuous-wave Spin-flip Laser Spectra 220
6 Opto-acoustic Spectroscopy with the Spin-flip Laser : Sensitivity
of Measurement 224
7 Infrared Photochemistry 230
8 Recent Developments 232
9 Summary 234
Chapter 6 Raman and Infrared Spectroscopy of Molecular
Crystals 235
By B. Schrader
1 Introduction 235
2 Experimental 236
3 Qualitative Picture of the Vibrational Spectra of Molecular
Crystals 237