1 Introduction (T. Miyazaki) .................................... 1
1.1 Atom Tunneling Phenomena .................................. 1
1.2 Aim of the Book ........................................... 4
1.3 Outline of the Book ....................................... 7
References ................................................... 11
Part 1 Atom Tunneling in Physics
2 Theory of Atom Tunneling Reactions in the Gas Phase
(T. Takayanagi) .............................................. 15
2.1 Introduction ............................................. 15
2.2 What is Tunneling in Chemical Reactions? ................. 16
2.3 Quantum Mechanical Methods for Calculating Rate
Constants ................................................ 18
2.4 Low Temperature Behavior of Rate Constants:
Wigner Threshold Law ..................................... 20
2.5 Effect of van der Waals Interactions on Tunneling
Reactions ................................................ 21
2.6 H + H2 Tunneling Reaction in Solid Phase:
Application of Gas-Phase Models .......................... 24
2.7 Tunneling in the F + H2, D2, and HD Reactions ............ 26
2.8 Conclusion and Future Development ........................ 28
References ................................................... 29
3 Theory of Atom Tunneling Reactions in the Solid Phase
(L.I. Trakhtenberg) .......................................... 33
3.1 Introduction ............................................. 33
3.2 Description of Low Temperature Chemical Reactions ........ 36
3.3 Experimental Data on H-Atom Tunneling and Fitting by
One Dimensional Model .................................... 42
3.4 Effect of Promotive Modes on the Rate Constant of Atom
Tunneling ................................................ 43
3.4.1 Relaxation Processes ............................... 44
3.4.2 Time of Tunneling Transition ....................... 44
3.4.3 Double Adiabatic Approximation ..................... 45
3.4.4 Modified Theory of Radiationless Transitions ....... 46
3.4.5 Comparison of Theory with Experimental Data ........ 48
3.5 Mechanisms of Temperature and Pressure Dependencies of
the Rate Constant ........................................ 49
3.5.1 Role of Medium Reorganization in D-Transfer in
an Irradiated HD Crystal ........................... 50
3.5.2 H-atom Tunneling in the Fluorene-Acridine System ... 52
3.6 Conclusion and Future Development ........................ 54
References ................................................... 55
4 Atom Tunneling Reactions in Quantum Solid Hydrogen
(T. Miyazaki) ................................................ 59
4.1 Introduction. Classical Reactions and Tunneling
Reactions ................................................ 59
4.1.1 Temperature Dependence ............................. 60
4.1.2 Isotope Effect ..................................... 62
4.2 ESR Measurement at Very Low Temperature .................. 63
4.3 Conclusive Evidence for Atom Tunneling Reactions ......... 64
4.3.1 Temperature Independence ........................... 65
4.3.2 Large Isotope Effect ............................... 66
4.3.3 Comparison of Experimental Rate Constants with
Theoretical Values ................................. 68
4.4 Controlling Factors of Classical Reactions ............... 70
4.5 Controlling Factors of Tunneling Reactions ............... 70
4.5.1 Effect of Deformation of Crystalline Structure ..... 70
4.5.2 Anomalous Temperature Effect on the Decay of H2-
Anions ............................................. 74
4.5.3 Effect of Disorder and Energy Dissipation .......... 77
4.5.4 Inverse Secondary Isotope Effect of Methyl
Radical Reactions .................................. 85
4.6 Fascinating Quantum Properties of Solid Hydrogen ......... 86
4.7 Conclusion and Future Development ........................ 87
References ................................................... 88
5 Atom Tunneling Phenomena in Quantum Solid and Liquid Helium
(Y. Miura) ................................................... 91
5.1 Introduction. Quantum Nature of Helium Atoms ............. 91
5.2 Nuclear Magnetic Ordering of Solid 3He Arising from
Tunneling of Atoms ....................................... 92
5.3 Quantum Nucleation in Superfluid Helium by Tunneling ..... 98
5.4 Tunneling Motion of Dislocation Lines in Solid 3He ...... 103
5.5 Conclusion and Future Development ....................... 108
References .................................................. 109
6 Quantum Tunneling Diffusion (R. Kadono) ..................... 111
6.1 Introduction ............................................ 111
6.2 Quantum Tunneling Diffusion of Positive Muons and
Muonium ................................................. 112
6.3 Effect of Disorder and Superconductivity ................ 115
6.4 Muonium in a Bloch State ................................ 117
6.5 Conclusion and Future Development ....................... 123
References .................................................. 123
Part 2 Atom Tunneling in Chemistry
7 Fascinating Aspects of Tunneling Reactions in Organic
Substances (T. Miyazaki) .................................... 127
7.1 Introduction ............................................ 127
7.2 Selective Tunneling Reaction in Alkane Mixtures by H
Atoms ................................................... 128
7.2.1 Formation of H Atoms in Radiolysis of Alkane ...... 128
7.2.2 Evidence for Tunneling Reaction ................... 131
7.2.3 Selectivity in Tunneling Reaction ................. 132
7.2.4 Local Motion and Selective Tunneling Reaction ..... 135
7.3 Selective Tunneling Reaction in the Same Alkane by H
Atoms ................................................... 138
7.4 Instability of Molecules. Tunneling Elimination of H2
Molecule from Alkane Cation ............................. 140
7.5 Instability of Molecules. Tunneling cis-trans
Isomerization of Formic Acid ............................ 144
7.6 Conclusion and Future Development ....................... 145
References .................................................. 145
8 Tunneling Insertion Reaction of Carbenes (H. Tomioka) ....... 147
8.1 Introduction ............................................ 147
8.1.1 Dicoordinate Carbon Intermediate-Carbenes ......... 147
8.1.2 Carbenes Have Two-Electronic States Singlet and
Triplet Multiplicities ............................ 148
8.1.3 Singlet and Triplet States Show Different
Reaction Patterns ................................. 149
8.1.4 How to Generate a Carbene ......................... 151
8.2 Reactions of Arylcarbenes with Alkenes at 77 К .......... 152
8.3 Reactions of Arylcarbenes with Alcohols at 77 К ......... 155
8.4 Tunneling C-H Insertion from Triplet Carbenes at Low
Temperature ............................................. 157
8.5 Why Can Only Triplets Find a Tunneling Pathway? ......... 160
8.6 Tunneling Reactions of Carbene Having Intramolecular
Reaction Channels ....................................... 161
8.7 Tunneling in Intramolecular Reactions ................... 164
8.8 Tunneling Reaction at Elevated Temperatures ............. 166
8.9 Conclusion and Future Development ....................... 170
References .................................................. 171
9 Production of Interstellar Molecules and Amorphous
Semiconductors by Atom Tunneling Reaction (K. Hiraoka) ...... 173
9.1 Introduction ............................................ 173
9.2 Method .................................................. 175
9.3 Laboratory Simulation of H-atom Tunneling Reactions in
Interstellar Ices ....................................... 177
9.3.1 Gas-Grain Processes for the Formation of NH3,
CH4, and H2O ...................................... 178
9.3.2 Formation of Formaldehyde by the Tunneling
Reaction of H with Solid CO at 10К ................ 182
9.3.3 Tunneling Reactions of H Atoms with Solid C2H2,
C2H4, andC2H6 ...................................... 184
9.3.4 Tunneling Reactions of D Atoms with C2H2, C2H4
and C2H6: Isotope Effect .......................... 189
9.3.5 Negative Temperature Dependence of H-Atom
Tunneling Reactions ............................... 190
9.4 Formation of Amorphous Semiconductor by H-Atom
Tunneling Reactions ..................................... 193
9.5 Conclusion and Future Development ....................... 197
References .................................................. 198
10 Atom Tunneling and Molecular Structure (H. Sekiya) ......... 201
10.1 Introduction .......................................... 201
10.2 Experimental Methods .................................. 201
10.3 Proton Tunneling in Molecules and Complexes ........... 206
10.3.1 Proton Tunneling in Molecules .................. 206
10.3.2 Proton Tunneling in Complexes .................. 219
10.4 Conclusion and Future Development ..................... 227
References ................................................. 228
11 Atom Tunneling and Crystalline Structure (T. Matsuo) ....... 233
11.1 Introduction .......................................... 233
11.2 General Considerations on X-Ray and Neutron
Diffraction, Crystal Structure and Phase
Transitions ........................................... 234
11.3 Proton Tunneling in Hydrogen-Bonded Crystals .......... 237
11.4 Tunneling Energy Levels of Ammonium Ions in Ammonium
Hexachlorometallates: Global and Local Rotation and
Tunneling ............................................. 245
11.5 Delocalization of H(D) Atoms.
Structure of (NH4)2PtCl6, (NH4)2SnCl6 and (ND4)2SnC6
by Neutron Diffraction ................................ 251
11.6 Other Compounds Possessing Strong Isotope-Dependent
Properties ............................................ 257
11.7 Conclusion and Future Development ..................... 258
References ................................................. 258
Part 3 Atom Tunneling in Biology
12 Atom Tunneling Reaction of Vitamin С in Suppression of
Mutation (T. Miyazaki and J. Kumagai) ...................... 263
12.1 Introduction .......................................... 263
12.1.1 Tunneling Reaction at Room Temperature ......... 263
12.1.2 How to Study Tunneling Reactions in
Biological Systems ............................. 265
12.2 Long-Lived Radicals in γ-Irradiated Cells ............. 267
12.2.1 Discovery of Long-Lived Radicals and
Reactions with Vitamin С ....................... 267
12.2.2 Why Do Reactive Radicals Survive for a Long
Time? .......................................... 269
12.2.3 Assignment of Long-Lived Radicals .............. 272
12.3 Reaction of Long-Lived Radicals with Vitamin С ........ 275
12.4 Biological Effects of Tunneling Reaction of
Long-Lived Radicals with Vitamin С .................... 277
12.5 Tunneling Reaction of Long-Lived Radicals with
Vitamin С ............................................. 280
12.6 Conclusion and Future Development ..................... 282
References ................................................. 283
13 Atom Tunneling Reaction of Vitamin E in Antioxidant,
Prooxidant and Regeneration Reactions (S. Nagaoka) ......... 285
13.1 Introduction .......................................... 285
13.2 Tunneling Antioxidant Reaction of Vitamin E ........... 289
13.3 Prooxidant Reaction of Vitamin E ...................... 295
13.4 Tunneling Regeneration Reaction of Vitamin E .......... 298
13.5 Conclusion and Future Development ..................... 301
References ................................................. 302
Index ......................................................... 305
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