Table Of ContentION-MOLECULE REACTIONS
Volume 1
CONTRIBUTORS
P. Ausloos Zdenek Herman
Physical Chemistry Division Institute of Physical Chemistry
Radiation Chemistry Section Czechoslovak Academy of Science
National Bureau of Standards Prague, Czechoslovakia
Washington, D. C.
Paul Kebarle
H. F. Calcote Chemistry Department
AeroChem Research Laboratories, Inc. University of Alberta
Sybron Corporation Edmonton, Alberta, Canada
Princeton, New Jersey
F. W.Lampe
William A. Chupka Whitmore Laboratory
Argonne National Laboratory The Pennsylvania State University
Argonne, Illinois University Park, Pennsylvania
Elden E. Ferguson S. G. Lias
Aeronomy Laboratory Physical Chemistry Division
ESSA Research Laboratories Radiation Chemistry Section
Boulder, Colorado National Bureau of Standards
Washington, D. C.
F. H. Field
Rockefeller University Einar Lindholm
New York, New York Physics Department Royal Institute
of Technology
J. L. Franklin Stockholm, Sweden
Department of Chemistry
Rice University John F. Paulson
Houston, Texas Air Force Cambridge Research Laboratories
L. G. Hanscom Field
Jean H. Futrell Bedford, Massachusetts
Department of Chemistry
University of Utah Stanley A. Studniarz
Westinghouse Research Laboratories
Salt Lake City, Utah
Beulah Road, Churchill Boro
Pittsburgh, Pennsylvania
Michael Henchman
Department of Chemistry Thomas O. Tiernan
Braddeis University Aerospace Research Laboratories
Waltham, Massachusetts
Wright·Patterson Air Force Base, Ohio
Jay M. S. Henis Richard Wolfgang
Monsanto Company Department of Chemistry
Central Research Department Yale University
St. Louis, Missouri New Haven, c.onnecticut
ION-MOLECULE REACTIONS
Volume I
Edited by
J. L. Franklin
Department of Chemistry
Rice University
Houston, Texas
<:P
PLENUM PRESS • NEW YORK • 1972
Libury of CongreN Cualog Card Number 77·179158
ISBN 978·1-4757-0090-9 ISBN 978-1-4757-0088-6 (eBook)
00110.10071978-1-4757-0088-6
«l 1972 Plenum Pren, New York
Softcover reprint of the hardcover 1st edition 1972
A Division of Plenum Publie.hing Corporation
221 Westl11h Street, New York, N.Y. 10011
All rights reserved
No part of thil publication may be reproduced in any form
without written permilsion from the publisher
DEDICATION
The tragic death of Professor Richard Wolfgang occurred shortly after
the completion of his portion of this book. His passing was a great loss
to science and especially to radiation chemistry and reaction dynamics.
It seems only fitting that these volumes should be dedicated to his memory.
Preface
After a few faint stirrings of interest in ion-molecule reactions during the
early days of mass spectrometry, the subject was almost completely neglected
for many years. There was a renascence of interest in the subject following
pioneering experiments by Tal'roze in Russia and independently by Steven
son and Schissler and Field, Franklin, and Lampe in this country. Since
that time, interest in the subject has continued to grow and the number of
papers published to expand almost exponentially during the past 15 years.
The result is a body of literature that is now almost beyond any single
individual's capacity for encompassing in his reading and research activities.
Thus, it seemed timely to prepare a book giving in some detail a comprehen
sive review of the field. Ideally, such a book would be written by one or
possibly two authors. Unfortunately, the sheer bulk and variety of the
studies of ion-molecule reactions has made it impractical for a single
person to prepare a book on the subject in a time that would permit it to
be issued before the material covered was obsolete. Consequently, the only
practical, although surely not the ideal, solution is to issue a multiauthor
volume. The present book represents our best efforts to accomplish this
goal. We have secured from 18 authors material representing the most
advanced work in the field and the resulting compilation is presented herein.
The result has turned out to be considerably longer than we had originally
anticipated and so it appeared preferable to publish the book in two volumes.
Again, it would be preferable if the subject matter could be comfortably
contained within the compass of a single volume but, unfortunately, this
did not prove to be the case.
The editor of a work such as this inevitably is indebted to a number of
people. Of course, my first debt is to the various authors, who have in all
cases been helpful and cooperative. I am especially indebted to my secretary,
Mrs. Jean Long, who has been invaluable in helping with the arrangements,
typing, and editing of the book. Finally, I must express my gratitude to my
wife, who has put up with a great deal in order that I might devote myself
to my editorial duties.
Houston, Texas J.L.F.
June, 1972
vii
Contents of Volume 1
Contents of Volume 2 . xv
Chapter 1. Introduction
J. L. Franklin .
Chapter 2. Positive-Ion-Molecule Reaction Studies in a
Single Electron-Impact Source
J. L. Franklin
1. The Continuous Ion Extraction Source. 9
2. Establishment of Ion-Molecule Reactions 10
3. Reaction Kinetics 14
4. The Pulsed Ion Source . 16
5. Energy Effects in Ion-Molecule Reactions. 17
6. Rate Method of Identifying Two Precursors of a Single Product 19
7. Reactions and Reaction Kinetics at Elevated Pressures 21
8. Reactions of Electronically Excited Ions . . 23
9. Residence Times from Mobilities 24
10. Energy Distribution in Products oflon-Molecule Reactions 26
11. Proton Affinities 29
References . 30
Chapter 3. Ion-Molecule Reactions by Photoionization Techniques
W. A. Chupka
1. Introduction 33
2. Experimental Technique 34
2.1. Optical Monochromator 34
2.2. Light Sources 36
2.3. Mass Spectrometers 37
2.4. Ion Sources and Reaction Chambers 38
2.5. Pulse Techniques 40
3. Photoionization Theory 40
3.1. General. 40
3.2. Direct Ionization 41
3.3. Autoionization 45
3.4. Ion-Pair Formation. 51
ix
x Contents of Volume 1
3.5. Preparation of Pure Ion Species. 51
3.6. Identification of Reactant Ions . 53
3.7. Preparation of Ions in States of Known Internal Energy 53
4. Reactions of Pure Ion Preparations . 59
4.1. Reactions in Propylene and l,3-Butadiene 59
4.2. Reactions in Methane . . 61
4.3. The Pulse Experiments of Warneck 61
4.4. High-Pressure Photoionization; Reactions of C4Hg + 62
4.5. Endoergic Reactions; Determination of Heats of
Formation from Thresholds . . . . 64
5. Reactions of Ions with Known Internal Energies 67
5.1. Reactions of NH3 + with NH3 and H20 67
5.2. Reactions of H2 + with H2 . . . . 69
5.3. Reactions of H2 + with He, Ne, and Ar 70
5.4. Charge Transfer in H2 73
References 74
Chapter 4. Negative-Ion-Neutral Reactions
J. F. Paulson
1. Introduction . . . . . . . 77
2. Sources of Negative Ions . . . 77
2.1. Dissociative Attachment. 77
2.2. Three-Body Attachment 78
2.3. Ion-Pair Production . 79
2.4. Radiative Attachment. 79
2.5. Ion-Neutral Reactions 80
3. Experimental Techniques. . 80
3.1. Ion-Source Method 80
3.2. Double Mass-Spectrometer Method 81
4. Experimental Results . . . . 83
4.1. Reactions of H- and D-. . . . . 83
4.2. Reactions of C-. . . . . . . . 85
4.3. Reactions of 0- with H2 and with O2 87
4.4. Reactions of 0 - with Some Triatomic Molecules 90
4.5. Additional Reactions with Diatomic and Triatomic
Molecules . . . . 92
5. Postscript 97
References . 97
Chapter 5. Rate Constants and Cross Sections
M. Henchman
1. General Survey . 101
1.1. Introduction 101
Contents of Volume 1 xi
1.2. Accuracy-Present Status and Present Need 102
1.3. Nomenclature . . . . . . . . . . . 104
1.4. The Ideal Experiment: Successive Refinement in the De
termination of a Reaction Rate. . . . . . . . . 104
1.5. Survey of Chapter Contents. . . . . . . . . . . 110
2. Rate Constants and Cross Sections-Some Formal Considera-
tions . . . . . . . . . . . . . . . . . . 110
2.1. The Relationship between Rate Constants and Cross
Sections . . . . 110
2.2. Unfolding Procedures. 113
2.3. Nonequilibrium Effects 114
2.4. Conclusions . . . . 116
3. Available Techniques . . . 116
3.1. Survey and Organization 116
3.2. Some General Problems 120
3.3. Beam Techniques . 125
3.4. Swarm Techniques. . 136
3.5. Plasma Techniques. . 163
3.6. Comparative Assessment of Techniques 168
4. Theoretical Prediction of Rate Parameters and
Comparison with Experiment. . . 184
4.1. Survey . . . . . . . . . . . . 184
4.2. Close-Collision Cross Sections. . . . 186
4.3. Trajectory Calculations over the Potential Energy
Hypersurface ......... . 204
4.4. Statistical Models . . . . . . . . . . 208
4.5. Crossings between Potential Energy Surfaces. 223
4.6. Direct Models at High Energies 228
5. Conclusion . . . . . . . . . . . . . . 230
5.1. Miscellaneous Topics. . . . . . . . . 230
5.2. Recommendations for the Adoption of Standard
Procedures . . . . 233
5.3. Survey and Prospects 235
Notes Added in Proof 238
Acknowledgments 245
References. . . . . 245
Chapter 6. Chemical Ionization Mass Spectrometry
F. H. Field
1. Introduction . . . . . . . . . . . 261
2. Experimental . . . . . . . . . . . 269
3. Mass Spectra of Different Compound Types 270
3.1. Alkanes. . . . . . . . . . . 270
xii Contents of Volume 1
3.2. Cycloparaffins 274
3.3. Alkenes and Alkynes 277
3.4. Aromatics. . . . 280
3.5. C7Hs Isomers 283
3.6. Chemical Ionization of Benzene by Rare Gas Reactants 284
3.7. Esters . . . . . . . 285
3.8. Alcohols . . . . . . . . . . 288
3.9. Miscellaneous Compounds. . . . 290
4. Temperature Effects in Chemical Ionization 292
4.1. Benzyl Acetate and t-Amyl Acetate Spectra at Various
Temperatures. . . . . . . . . . . .. 293
4.2. Mathematical Formulation of Chemical Ionization
Kinetics. . . . . . . . . . . . . .. 295
4.3. Kinetic Results for Benzyl Acetate and t-Amyl Acetate 298
4.4. Pressure Studies with Benzyl Acetate . . . . .. 300
4.5. Substituted Benzyl Acetates. . . . . . . . .. 302
4.6. Methoxymethyl Formate and Methoxymethyl Acetate 304
4.7. Methylthiomethyl Acetate and Methylthiomethyl
Propionate . . . . . . 307
4.8. Equilibrium Reactions 308
References. . . . . . . . . . . 312
Chapter 7. Higher-Order Reaction-Ion Clusters and Ion Solvation
P. Kebarle
1. Introduction . . . . . . . . . . . . . . . 315
2. Ion-Molecule Reactions at Conventional Gas Kinetic
Conditions . . . . . . . . . . . . . . . 317
3. Apparatus for Mass Spectrometric Studies of Ion-Molecule
Reactions at Pressures Above 1 Torr and Thermal Energies 319
4. Kinetics and Mechanism of Clustering Reactions. The Proton
Hydrates. Applications. . . . . . . . . . . .. 327
5. Ionic Clustering Equilibria-Determination of Enthalpy and
Entropy Changes of Clustering Reactions . . . . .. 333
6. Ionic Solvation in the Gas Phase . . . . . . . . .. 338
6.1. Application of Gas-Phase Cluster Studies to Ion-Solvent
Molecule Interactions and Heterolytic Organic Reac-
tions . . . . . . . . . . . . . . 338
6.2. Gas-Phase Hydration of Alkali and Halide Ions. .. 341
6.3. The Hydrated Proton in the Gas Phase . . . " 345
6.4. Competitive Solvation in the Gas Phase. H+ by Water
and Methanol and by Water and Ammonia Molecules 346
6.5. Solvation of Negative Ions by Various Solvent Molecules.
Correlation with Acidity. . . . . . . . . . . 351
