320 Scanning Vol. 16.5 (1994)

Book Reviews Scanning7hnnelingMicroscopyII

Edited by R. Wiesendanger and H.-J. Guntherodt

Springer-Verlag, New York ( 1992) ISBN 0-387-54555-7; illustrated $69.00

Describing the early development of scanning tunneling microscopy in Nature, the Editor wrote in 1985, “If you have a particle or a field of some kind whose interaction with mater- ial objects varies with their constitution, the chances are that you will be able to fashion a microscope from the phenome- non.” In Volume I of their three-volume series, Wiesendanger and Guntherodt concentrated on scanning tunneling micro- scopy (STM) principally in its purest form in ultra high vac- uum. In Volume 11, they extend the coverage first to STM in electrochemistry and biology, and then to other scanning probe techniques. The first chapter gives a useful introduction by the editors setting the scene, and the individual chapters which fol- low maintain the high standard which they established in the first volume.

Most of the chapters begin with the relevant fundamental principles. The principles of operating an STM in an electri- cal environment are splendidly set out in the first figure and the accompanying text. The chapters on magnetic force microscopy and on near-field optical microscopy also give particularly clear accounts of the basic principles of their tech- niques. The force microscopy chapter contains a useful sum- mary of the wide range of forces which may be present and the mechanical effects which may accompany them, including such ubiquitous effects in air as liquid capillary effects. The book is rich in practical experimental detail. The electro- chemical chapter gives specific circuits for bipotentiostats which require considerably more demanding specifications for STM than for routine chemistry. There are detailed accounts of tip preparation, specific for each case, in the chap- ters on electrochemistry, force microscopy, magnetic force microscopy, and near-field optical microscopy. The electro- chemical and biological chapters give helpful information on specimen preparation and some timely reminders of the pos- sible pitfalls in scanning the samples and in the subsequent image interpretation.

The chapters are rich in applications of their techniques. Electrochemical STM is illustrated by a range of deposition/ dissolution sequences on silver and gold substrates. Biological STM is illustrated by obligatory images of DNA (one in colour) and by some spectacular pictures of adenine molecules and purple membrane. Both force microscopy and magnetic force microscopy find major applications in the field of record- ing media, and some excellent examples of this are given. The chapters on Related scanning techniques and on Surface mod- ification do not give as much detail as the other chapters and as their subject matter would deserve, but they both contain suf- ficiently fascinating applications to whet the appetite of the reader to follow up the references.

This volume is a splendidcollection of definitive articles by scientists who are authorities in their fields. Practitioners of STM will want to have a copy on their bookshelf.

Andrew Briggs University of Oxford

Scanning~nnelingMicroScopy III Edited by R. Wiesendanger and H.-J. Guntherodt

Springer-Verlag, New York (1993) ISBN 0-387-563 17-2; illustrated, 375 pages, $79.00

Some of the chapters in the first two volumes of this series contain a good account of the underlying theory. In Volume 11, the magnetic force and near-field optical chapters may be sin- gled out for special praise in this respect. In other places, the need for adequate theory is explicitly acknowledged. In elec- trochemical scanning tunneling microscopy (STM), there is a need for better understanding both of the apparent tunneling barrier heights and of the diffusional transport patterns and the electric potential distributions. In scanning force microscopy (SFM), “The theoretical treatment of SFM has proven to be a complex problem.” (Vol. 11, p. 99). The editors have therefore devoted the third volume of their series to the theory of STM and related scanning probe methods.

After another useful introduction by the editors, there are four accounts of basic imaging and spectroscopy theory for STM, including tip effects. There is then a chapter on the tun- neling time problem. A unified pembation theory for STM and SFh4 follows, summarizing some of the work which is pre- sented in a more complete account in Chen’s book (OW 1993) (reviewed in Vol. 16, No. 2). The next chapter is about the the- ory of tipsample interactions, including both mechanical and electronic effects, and the consequences of these are illustrated (in colour) by some beautiful atomistic simulations in the next chapter. The remaining three chapters are devoted to theory of force microscopy, divided into contact force microscopy, atomic-scale friction, and noncontact force microscopy. There are no chapters on some of the other needs mentioned in Vol. II, such as STM in electrochemical environments.

As we have come to expect in this series, the chapters are written by scientists who have made significant contributions and who write with clarity and authority. I believe, however, that they have found it difficult to be as definitive in their accounts as was possible in the earlier two volumes. In any symposium of this kind there is a tension between giving a clear and com- plete account and being fully up to date, and it is possible to achieve both only when one is writing about an aspect of the subject that has established a settled form. For example, the first full chapter, by Lang, contains a beautiful account by someone who pioneered many STM calculations, notably of single atoms. The most recent references to theory in that chapter were published in 1989 (there are two references to experimental workpublishedin 1991).Themorerecenttheoryinotherchap- ters may well be correct, but in some cases has yet to be proved robust in routine use. And there has certainly been a great deal of theoretical work since this book went to press of which any- one active in the field will wish to be aware.

It may be, therefore, that this volume will be more difficult to use than the first two. Perhaps readers will be less likely to turn to it for ready-made theoretical formalisms that they can use directly in their own work, but ratherto learn the state of knowl- edge in 1993 to provide a foundation for following the subse- quent literature. For that purpose, this volume is excellent.

Andrew Briggs University of Oxford