DISSOCIATIVE RECOMBINATION OF
MOLECULAR IONS

Dissociative recombination (DR) of molecular ions with electrons is a complex, poorly understood molecular process. Its critical role as a neutralizing agent in the Earth’s upper atmosphere is now well established and its occurrence in many natural and laboratory produced plasmas has been a strong motivation for studying the event. For the first time, theoretical concepts, experimental methodology, and applications are united in one book, revealing the governing principles behind the gas-phase reaction. The book takes the reader through the intellectual challenges posed, describing in detail dissociation mechanisms, dynamics, diatomic and polyatomic ions, and related processes, including dissociative excitation, ionpair formation and photodissociation. With the final chapter dedicated to applications in astrophysics, atmospheric science, plasma physics, and fusion research, this is a focused, definitive guide to a fundamental molecular process. The book will appeal to academics within physics, physical chemistry, and related sciences.

MATS LARSSON is a Professor and Experimentalist in the Physics Department at Stockholm University. He obtained his Ph.D. in physics in the Research Institute of Physics and Stockholm University. His research interests include primary chemical reactions, interstellar chemistry, and molecular spectroscopy. He was a member of the Physics and Mathematics Committee of the Swedish Natural Science Research Council from 1989 to 1995. He was made chair of the Research Committee of the Swedish National Space Board in 2001, and was also chair of the Evaluation Committee for Atomic and Molecular Physics, Fusion Research and Plasma Physics of the Swedish Research Council from 2001 to 2003.

ANN E. OREL is a Professor and Chair in the Department of Applied Sciences at the University of California, Davis. She obtained her Ph.D. in chemistry at the University of California, Berkeley and was made a fellow of the American Physical Society in 2000. Her research interests include theoretical atomic and molecular physics and computational science.

DISSOCIATIVE RECOMBINATION OF
MOLECULAR IONS

MATS LARSSON
Stockholm University

and

ANN E. OREL
University of California, Davis

CAMBRIDGE UNIVERSITY PRESS
Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo

Cambridge University Press
The Edinburgh Building, Cambridge CB2 8RU, UK

Published in the United States of America by Cambridge University Press, New York

www.cambridge.org

© M. Larsson and A. E. Orel 2008

This publication is in copyright. Subject to statutory exception
and to the provisions of relevant collective licensing agreements,
no reproduction of any part may take place without
the written permission of Cambridge University Press.

First published 2008

Printed in the United Kingdom at the University Press, Cambridge

A catalog record for this publication is available from the British Library

ISBN 978-0-521-82819-2 hardback

Cambridge University Press has no responsibility for the persistence or accuracy of URLs for external or third-party internet websites
referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate.

We would like to dedicate this book to Sheldon Datz, who was responsible for
introducing us to this interesting area of physics.

Contents

Preface

This research monograph provides a single-volume description of the dissociative recombination of molecular ions with electrons. Since this is one of the most complex gas-phase processes, its study is a challenge to theorists and experimentalists alike. The theory, experiment, and applications of dissociative recombination are scattered in the scientific literature as original research articles, conference proceedings, and review articles. This book brings this information together in a single work for the first time.

   The book is intended for researchers and Ph.D. students in the fields of atomic and molecular physics, chemical physics and physical chemistry, molecular astrophysics, atmospheric physics, and other areas of science where electrons and molecular ions are important.

   This book was written during a period when each of us had several other commitments which slowed down the writing. One of us (AEO) was department chair at UC Davis essentially during the entire writing process, and ML chaired committees for the Swedish Space Board and the Swedish Research Council.

   We are grateful for the hospitality of the Institute for Atomic and Molecular Physics (ITAMP) at the Harvard-Smithsonian Center for Astrophysics and Harvard University Physics Department (Kate Kirby, Hussein Sadeghpour), the Cluster Research Laboratory, Toyota Technological Institute, Tokyo (Tamotsu Kondow), and the University of Chicago (Takeshi Oka), all of which provided excellent working conditions for us when we needed to get away from our home institutions to focus on writing.

   Several people have assisted us in reading part of the book and making valuable suggestions: Alex Dalgarno, Shirzad Kalhori, Holger Kreckel, Åsa Larson, Valery Ngassam, Takeshi Oka, Jeanna Royal, Albert Viggiano and Vitali Zhaunerchyk. We offer them our sincerest thanks for their help.

   Finally we would like to thank Rainer Johnson, Brian Mitchell, Ioan Schneider, Andreas Wolf, Chris Greene, and the members of our research groups for access to material prior to publication.