In 2001 Wyn Roberts celebrated both his 70th birthday and 50 years of working in surface science, to use the term "surface science" in its broadest meaning. This book aims to mark the anniversary with a contribution of lasting value, something more than the usual festschrift issue of a relevant journal. The book is divided into three sections: Surface Science, Model Catalysts and Catalysis, topics in which Wyn has always had interests. The authors for each chapter were chosen from some of the many eminent scientists who have worked with Wyn in various ways and are all internationally acknowledged as leaders in their field. The authors have produced authoritative reviews of their own specialties which together result in a book with an unrivalled combination of breadth and depth exploring the most recent developments in surface chemistry and catalysis.

The Chemical Physics of Solid Surfaces, Volume 6: Coadsorption, Promoters, and Poisons focuses on the processes, reactions, and approaches involved in coadsorption and the functions of promoters and poisons in synthesis and reactions. The selection first offers information on adsorbate-adsorbate interactions on metal surfaces and interaction between alkali metal adsorbates and adsorbed molecules. Discussions focus on coadsorption of alkali metals and other molecules; model experiments of catalyst promotion; effective medium theory; direct and indirect hybridization effects; and elastic interaction between adsorbates. The publication then ponders on coadsorption of carbon monoxide and hydrogen on metal surfaces and adsorption on bimetallic surfaces. The manuscript examines the chemical properties of alloy single crystal surfaces and promotion in ammonia synthesis. Topics include substrate dependence of nitrogen adsorption and ammonia synthesis; effects of promotion on nitrogen dissociation and ammonia synthesis; and theoretical modeling. The text then elaborates on promotion in the Fischer-Tropsch hydrocarbon synthesis, promoters and poisons in the water-gas shift reaction, and strong metal-support interactions. The selection is a recommended reference for physicists and readers interested in coadsorption, promoters, and poisons.

Reflecting the growing volume of published work in this field, researchers will find this book an invaluable source of information on current methods and applications.

of available information. Even more importantly, some authors who have contributed substantially to an area may have been overlooked. For this I apologize. I have, however, not attempted to trace techniques or observa tions historically, so there is no implication (unless specified) that the authors referred to were or were not the originators of a given method or observation. I would like to acknowledge discussions with co-workers at SFU for input relative to their specialties, to acknowledge the help of students who have pointed out errors and difficulties in the earlier presentation, and to acknowledge the infinite patience of my wife Phyllis while I spent my sabbatical and more in libraries and punching computers. S. Roy Morrison 0 1 Contents Notation XV 1. Introduction 1 1. 1. Surface States and Surface Sites . 1 1. 1. 1. The Chemical versus Electronic Representation of the Surface. 1 1. 1. 2. The Surface State on the Band Diagram 4 1. 1. 3. The Fermi Energy in the Surface State Model. 6 1. 1. 4. Need for Both Surface Site and Surface State Models 6 1. 2. Bonding of Foreign Species to the Solid Surface 7 1. 2. 1. Types of Interaction. 7 1. 2. 2. The Chemical Bond . 10 1. 2. 3. Acid and Basic Surface Sites on Solids . 13 1. 2. 4. Adsorbate Bonding on Various Solid Types. 16 1. 2. 5. Movement of Surface Atoms: Relaxation, Reconstruction, and Relocation .