Radicals on Surfaces Topics in Molecular Organization and Engineering

RADICALS ON SURFACES TOPICS IN MOLECULAR ORGANIZATION AND ENGINEERING

Volume 13

Honorary ChiefEditor: W. N. LIPSCOMB (Harvard, Us.A.)

Executive Editor:

Jean MARUANI (Paris, France)

Editorial Board:

Henri ATLAN (Jerusalem, Israel) Alexandre LAFORGUE (Reims, France) Sir Derek BARTON (Texas, USA.) I-M. LEHN (Strasbourg, France) Christiane BONNELLE (Paris, France) P-O. LOWDIN (Uppsala, Sweden) Paul CARO (Meudon, France) Patrick MacLEOD (Massy, France) Stefan CHRISTOV (Sofia, Bulgaria) H. M. McCONNELL (Stanford, USA.) I. G. CSIZMADIA (Toronto, Canada) C. A. McDOWELL (Vancouver, Canada) P-G. DE GENNES (Paris, France) Roy McWEENY (Pisa, Italy) I-E. DUBOIS (Paris, France) I1ya PRIGOGINE (Brussels, Belgium) Manfred EIGEN (Gottingen, Germany) Paul RIGNY (Saclay, France) Kenishi FUKUI (Kyoto, Japan) R. G. WOOLLEY (Nottingham, UK.) Gerhard HERZBERG (Ottawa, Canada)

The titles published in this series are listed at the end ofthis volume. RADICALS ON SURFACES

Edited by

Anders Lund

and Christopher J. Rhodes

.. SPRINGER-SCIENCE+BUSINESS MEDIA, B.V. Library of Congress Cataloging-in-Publication Data

Radicals on surfaces I edited by Anders Lund and Christopher Rhodes. p. cm. -- (Topics in molecular organizat ion and englneering v. 13) Includes index. ISBN 978-94-010-4221-5 ISBN 978-94-011-0493-7 (eBook) DOI 10.1007/978-94-011-0493-7 1. Surface chemistry. 2. Free radicals (Chemistry) 3. Catalysis. I. Lund, A. (Anders) II. Rhodes, Christopher. III. Series. QD506.R24 1995 541.3' 3--dc20 94-31444

ISBN 978-94-010-4221-5

"The logo on the front cover represents the generative hyperstructure of alkanes", printed with permission from J.E, Dubois, Institut de Topologie et de Dynamique des Systemes, Paris, France.

Printed an acid-free paper

AII Rights Reserved © 1995 Springer Science+Business Media Dordrecht Originally published by Kluwer Academic Publishers in 1995 Softcover reprint ofthe hardcover Ist edition 1995 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any information storage and retrieval system, without written permission from the copyright owner. Introduction to the Series

The Series 'Topics in Molecular Organization and Engineering' was initiated by the Symposium 'Molecules in Physics, Chemistry, and Biology', which was held in Paris in 1986. Appropriately dedicated to Professor Raymond Daudel, the symposium was both broad in its scope and penetrating in its detail. The sections of the symposium were: 1. The Concept of a Molecule; 2. Statics and Dynamics of Isolated Molecules; 3. Molecular Interactions, Aggregates and Materials; 4. Molecules in the Biological Sciences, and 5. Molecules in Neurobiology and So• ciobiology. There were invited lectures, poster sessions and, at the end, a wide• ranging general discussion, appropriate to Professor Daudel's long and distin• guished career in science and his interests in philosophy and the arts. These proceedings have been arranged into eighteen chapters which make up the first four volumes of this series: Volume I, 'General Introduction to Molecular Sciences'; Volume II, 'Physical Aspects of Molecular Systems'; Volume III, 'Elec• tronic Structure and Chemical Reactivity'; and Volume IV, 'Molecular Phenomena in Biological Sciences'. The molecular concept includes the logical basis for geo• metrical and electronic structures, thermodynamic and kinetic properties, states of aggregation, physical and chemical transformations, specificity of biologically important interactions, and experimental and theoretical methods for studies of these properties. The scientific subjects range therefore through the fundamentals of physics, solid-state properties, all branches of chemistry, biochemistry, and molecular biology. In some of the essays, the authors consider relationships to more philosophic or artistic matters. In Science, every concept, question, conclusion, experimental result, method, theory or relationship is always open to reexamination. Molecules do exist! Never• theless, there are serious questions about precise definition. Some of these ques• tions lie at the foundations of modern physics, and some involve states of aggre• gation or extreme conditions such as intense radiation fields or the region of the continuum. There are some molecular properties that are definable only within limits, for example, the geometrical structure of non-rigid molecules, properties consistent with the uncertainty principle, or those limited by the neglect of quan• tum-field, relativistic or other effects. And there are properties which depend specifically on a state of aggregation, such as superconductivity, ferroelectric (and anti), ferromagnetic (and anti), superftuidity, excitons, polarons, etc. Thus, any molecular definition may need to be extended in a more complex situation. Chemistry, more than any other science, creates most of its new materials. At least so far, synthesis of new molecules is not represented in this series, although the principles of chemical reactivity and the statistical mechanical aspects are included. Similarly, it is the more physico-chemical aspects of biochemistry, mol• ecular biology and biology itself that are addressed by the examination of questions related to molecular recognition, immunological specificity, molecular pathology, photochemical effects, and molecular communication within the living organism.

v VI INTRODUCTION TO THE SERIES Many of these questions, and others, are to be considered in the Series 'Topics in Molecular Organization and Engineering'. In the first four volumes a central core is presented, partiy with some emphasis on Theoretical and Physical Chemis• try. In later volumes, sets of related papers as well as single monographs are to be expected; these may arise from proceedings of symposia, invitations for papers on specific topics, initiatives from authors, or translations. Given the very rapid development of the scope of molecular sciences, both within disciplines and across disciplinary lines, it will be interesting to see how the topics of later volumes of this series expand our knowledge and ideas.

WILLIAM N. LIPSCOMB Table of Contents

ANDERS LUND AND CHRIS RHODES / Introduction IX

Part I: Properties of Catalytic Surfaces 1

1.1 CATHERINE LOUIS, CHRISTINE LEPETIT, AND MICHEL CHE / EPR Characterization of Oxide Supported Transition Metal Ions: Relevance to Catalysis 3

1.2 R. 1. SAMOILOVA, A. D. MILOV, AND YU. D. TSVETKOV / Study of Catalytic Site Structure and Diffusion of Radicals in Porous Heterogeneous Systems with ESR, ENDOR and ESE 39

1.3 MASAHIDE OHNO / Theoretical Studies of Core Ionization, Excitation and De-excitation of Adsorbates 61

Part II: Structure and Reactivity of Radicals on Surfaces 87

11.1 R. B. CLARKSON, KAREN MATTSON, WENJUN SHI, WEI WANG, AND R. L. BELFORD / Electron Magnetic Resonance of Aromatic Radicals on Metal Oxide Surfaces 89

II.2 CHRISTOPHER 1. RHODES AND CHANTAL S. HINDS / ESR Studies of Organic Radical Cations in Zeolites 119

II.3 ELiO GIAMELLO AND DAMIEN MURPHY / Surface Trapped Electrons on Metal Vapour Modified Magnesium Oxide. Nature of Surface Centres and Reactivity with Adsorbed Molecules 147

II.4 MASARU SHIOTANI AND MIKAEL LINDGREN / Radicals on Surfaces Formed by Ionizing Radiation 179

II.5 ALEXANDER M. VOLODIN, VADIM A. BOLSHOV, AND TATIANA A. KONOVALOVA/ Photostimulated Formation of Radicals on Oxide Surfaces 201

Part III: Trends in Modern Techniques 227

III.1 HANS VAN WILLIGEN AND PATRICIA R.· LEVSTEIN / Fourier Transform Electron Paramagnetic Resonance Studies of Photochemical Reactions in Heterogeneous Media 229

III.2 EMIL RODUNER, MARTINA SCHWAGER, AND MEE SHELLEY / Muon Spin Resonance of Radicals on Surfaces 259

vii VI1l CONTENTS

111.3 RONALD L. BIRKE AND JOHN R. LOMBARDI / Investigation of Radical Ions with Time-Resolved Surface Enhanced Raman Spectroscopy 277

INDEX 311 Introduction

The entire area of 'catalysis' is one of immense current actIvIty, as befits the intellectual and commercial challenges which it provides. A great deal is known regarding the physical properties of catalytic materials, particularly from tech• niques such as NMR, and studies of adsorbed molecules are the cornerstone of 'surface science'. What is less clear, however, are the mechanistic details by which molecular transformations occur on catalyst surfaces, but growing evidence tends to implicate organic free radicals as intermediates in a number of reactions • particularly those catalysed by zeolites and other metal oxides. The present book addresses the broad aspect of radicals on surfaces, and con• cerns the properties of paramagnetic surface sites, the structure and reactivity of radicals on surfaces, and those trends and developments in spectroscopic tech• niques which are revealing new horizons of this topic. We have invited specialists from around the world to contribute a chapter relating to one of the above topics, presented in the manner of a review: collec• tively, thus, we have an overview of the state of current knowledge, but we envisage that this will be added to as the various sub-areas progress. Since this is, predominantly, a book about radicals, we have quite deliberately avoided coverage of conventional surface science techniques, which are well dealt with elsewhere. We are grateful to all our colleagues for their contributions, and to the editorial staff of Kluwer Academic Publishers, particularly Dr. David Lamer, for their invaluable cooperation.

ANDERS LUND CHRIS RHODES