CHEMICAL KINETICS EDITED BY C. H. BAMFORD M.A., Ph.D., Sc.D. (Cantab.), F.R.I.C, F.R.S. Campbell-Brown Professor of Industriell Chemistry, University of Liverpool AND C. F. H. TIPPER Ph.D. (Bristol), D.Sc. (Edinburgh) Senior Lecturer in Physical Chemistry, University of Liverpool VOLUME 3 THE FORMATION AND DECAY OF EXCITED SPECIES ELSEVIER PUBLISHING COMPANY AMSTERDAM - LONDON - NEW YORK 1969
Contents Preface Chapter 1 (C. S. BURTON AND W. A. NOYES, JR.) Effect of low energy radiation vn 1 1. INTRODUCTION 1 2. SURVEY OF THE PRIMARY EFFECTS OF ELECTROMAGNETIC RADIATION 2 2.1 Sensitization by monatomic gases 3 2.2 Photosensitization by mercury vapor 5 2.3 Absorption by diatomic gases 19 2.4 Absorption by polyatomic gases 33 2.4.1 Dissociation into atoms and radicals 36 2.4.2 Dissociation into complete molecules 45 2.4.3 Rearrangements 50 2.4.4 Summary of basic problems 55 3. EXPERIMENTAL PROBLEMS 58 4. DIFFERENT RADIATION TYPES. CONCLUSIONS 60 REFERENCES 63 Chapter 2 (G. HUGHES) Effect of high energy radiation 1. INTERACTION OF HIGH ENERGY RADIATION WITH MATTER 67 1.1 Mechanism of energy loss 67 1.2 Species produced in an irradiated System 68 1.3 Time scale of events 71 1.4 Comparison with photochemistry 72 2. EXPERIMENTAL EVIDENCE FOR SPECIES PRESENT 72 2.1 Ions and electrons 73 2.1.1 Gaseous Systems 74 2.1.2 Liquid Systems 77 2.1.3 Solid Systems 84 2.2 Free radicals 86 2.2.1 ESR data 87 2.2.2 Spectra 89 2.2.3 Chemical inferences of radical production 92 2.3 Excited molecules 98 3. CONCLUSION 103 REFERENCES 103 67
X CONTENTS Chapter 3 (T. CARRINGTON AND D. GARVIN) The chemical production of excited states 107 1. INTRODUCTION 107 1.1 Distribution of reaction products over internal energy states 107 1.2 Models of reaction 108 1.2.1 Kinematic modeis 108 1.2.2 Potential energy surfaces 110 1.2.3 Reactions on a Single Potential surface 111 1.2.4 Reactions involving morethan one Potential surface 113 1.3 Correlation rules 115 1.4 Rotational excitation 116 2. VIBRATIONAL EXCITATION 117 2.1 Atom- or group-transfer reactions 117 2.1.1 Flash photolysis: molecular oxygen and hydroxyl 119 2.1.2 Atom-molecule reactions studied in flow Systems: the hydrogen halide system 127 2.1.3 Comparison of molecular oxygen and hydrogen halide excitation.... 129 2.1.4 Excitation of alkali metal salts 130 2.1.5 Distribution of excitation between the reaction products 132 2.2 Four-center exchange reactions 134 2.3 Combination reactions producing vibrational excitation 135 2.3.1 Addition of hydrogen atoms to alkenes 136 2.3.2 Addition and insertion reactions ofmethylene 136 2.3.3 Combination of free radicals 138 2.4 Excitation in decomposition reactions 139 3. ELECTRONIC EXCITATION 139 3.1 The radiative recombination of atoms 139 3.1.1 Helium atom recombination 140 3.1.2 Halogen recombination 141 3.1.3 Association reactions of oxygen atoms 146 3.1.4 Nitrogen atom recombination 150 3.2 Recombination of atoms with excitation of the third body 152 3.3 The radiative combination of an atom with a diatomic molecule 156 3.3.1 O+NO =NO c 2 156 3.3.2 O+CO = CO e 2 160 3.3.3 O+SO = SO c 2 161 3.3.4 H+NO = HNO" 162 3.3.5 H+OH = H 2 0 164 3.4 Atom transfer reactions 164 3.4.1 A+BC-*AB e +C 164 3.4.2 A+BC->AB+C e 165 3.4.3 Transfer reactions in Systems of more than three atoms 166 3.5 Complex chemiluminescent Systems 167 3.5.1 Excitation of additives in active nitrogen 167 3.5.2 Reaction of oxygen atoms with acetylene 170 4. ROTATIONAL EXCITATION 170 5. CHEMICAL LASERS 171 Acknowledgement 174 REFERENCES 174
CONTENTS XI Chapter 4 (A. B. CALLEAR AND J. D. LAMBERT) The transfer of energy between chemical species 182 1. INTRODUCTION 182 2. EXPERIMENTAL MEASUREMENT OF RELAXATION TIMES 184 2.1 Acoustic methods 184 2.2 Shock-tube methods 187 2.3 Spectroscopic methods 189 3. THEORETICAL CONSIDERATIONS 192 3.1 The Landau-Teller theory 192 3.2 General principles of wave-mechanical treatment 193 3.3 Vibrational excitation 195 3.4 The interaction potential 196 3.5 Translational overlap 199 3.6 Vibrational matrix elements 200 3.7 Transition probability 202 3.8 Tanczos' theory for polyatomic molecules 205 3.9 Orientation and low-temperature effects 207 3.10 Exact quantum mechanical treatment 207 3.11 Conclusion 208 4. VIBRATION-TRANSLATION TRANSFER 209 4.1 Diatomic molecules 209 4.2 Polyatomic molecules 213 4.3 Mixtures 217 5. VIBRATION-VIBRATION TRANSFER 220 5.1 Intramolecular transfer of vibrational energy 220 5.2 Intermolecular transfer of vibrational energy 222 5.2.1 Ultrasonic dispersion in mixtures 222 5.2.2 Spectroscopic evidence 226 5.3 Theoretical discussion 227 5.4 Mechanisms of vibrational excitation 230 6. ROTATION-TRANSLATION TRANSFER 231 7. ROTATION-VIBRATION TRANSFER 235 8. ELECTRONIC-TRANSLATION AND ELECTRONIC-VIBRATION RELAXATION WITH AE < 1 ev 237 8.1 General considerations 237 8.2 Cross sections for energy transfer 239 8.3 Spin-orbit relaxation in selenium 242 8.4 Relaxation of atomic iron 244 8.5 Spin-orbit relaxation of highly excited species 249 8.6 Variation of cross-section with change in internal energy 250 8.7 Relaxation of atomic iodine 251 9. ELECTRONIC-VIBRATION AND ELECTRONIC-TRANSLATION ENERGY TRANSFER WITH J» 1 ev 253 9.1 Quenching and excitation of atomic sodium 253 9.2 Detection of vibrational excitation by infrared emission 254 9.3 Theory of quenching 255 10. ELECTRONIC-ELECTRONIC ENERGY TRANSFER 256 10.1 Introduction 256
XII CONTENTS 10.2 Mercury sensitised fluorescence 257 10.3 Electronic excitation transfer between inert gas atoms 259 10.4 Cross-sections for electronic energy transfer 260 10.5 Electronic excitation transfer in complex Systems 262 11. APPLICATION TO REACTION KINETICS AND PHOTOCHEMISTRY 263 11.1 Unimolecular reactions 263 11.2 Energy distribution in chemical reactions 266 12. CONCLUSION 268 REFERENCES 269