586 Nuclear Instruments and Methods in Physics Research B61 (1991) 586-588 North-Holland

Book review

This section of NIM B will bring reviews of books relevant for the regular readership of the journal. Books for review should be sent to one of the Editors.

SURFACE ANALYTICAL TECHNIQUES by J.C. Riviere (Oxford University Press, Oxford, 1990) pp. xxiii + 702, f75.00, hardcover, ISBN o-19-851370-4

Level: Graduate Reviewer: Jens Onsgaard, Odense

Over the past 20 years surface physics and surface chemistry have undergone a strong development. A new generation of surface analytical techniques to characterize the surface region of materials has emerged. There is definitely a need for description of the methods for materials scientists, seniors and gradu- ate students.

The aim of the author is to achieve - in view of the remarkable proliferation of surface compositional tech- niques - clarification. This is obtained by a description of the physical principles, the method of operation, the range of apphcation and the advantages of the current techniques. In order to limit the huge field two restric- tions are introduced. Only techniques that are surface-specific are dealt with and methods for studying the structure are excluded.

Riviere chooses to let the techniques themselves define the term, “surface”, since they are concerned with only the first few atom layers, extending to at most about 5 nm from the “true” surface, that is the point at which the material actually terminates. With this broad definition both KS and XPS are incorpo- rated into surface-specific techniques, although many surface scientists will consider ISS as a real surface- specific method and let the surface information depth of XPS depend on the kinetic energy of the emitted photoelectron. A useful list of acronyms of the many, forty-five, analytical techniques are given in the intro- duction.

In order to group the many analytical tools, the nature of the incident radiation is chosen as a crite- rion. This scheme is followed in Chapter 2 where the physical principles behind the headlines electron excita- tion, photon excitation and ion excitation, are briefly introduced. Twenty subsections list the big number of spectroscopies derived from the three types of excita- tions plus different types of mass spectrometry, and other techniques like field ion microscopy, scanning

tunneling microscopy (STM) and thermal desorption spectroscopy. Thus this chapter functions as a menu for the next 21 chapters. The reader gets the impres- sion that this book is an encyclopedia. This is con- firmed by the rigid structure of the contents in the individual chapters according to “operation”, “theory and spectral interpretation”, “quantification and appli- cations”, and “references”.

Yet, before the author opens for the first spec- troscopy, a single chapter is dedicated to instrumenta- tion, where different sources and analysers are de- scribed. Sample insertion, handlings and depth profil- ing are treated in an introductory manner.

Obviously it is appropiate to include common prin- ciples and apparatus in the initial phase of the book. It would have been adequate to introduce the concepts of cross section, convolution/deconvolution, nomencla- ture, etc. at an early stage instead of the late applica- tion in some specific context. They are general tools that give newcomers a frame.

Methods based on electron excitation are described in Chapters 4-9 corresponding to 25% of the volume dealing with the techniques. Auger electron spec- troscopy (AES) and scanning Auger electron spec- troscopy (SAM) are given almost a third of the elec- tronic excitation part. Following the typical chapter organization a phenomenological introduction to AES is given in the first section with figures showing a secondary electron energy distribution from a sample and a typical experimental arrangement. After going through the notations in the three couplings, character- istic Auger spectra from the literature are shown. Spectral interpretation and features are pointed out, again illustrated with several figures. The typical quan- tification procedure is given, followed by closing re- marks on the accuracy and on the difficulties in obtain- ing absolute concentrations. Best results are obtained in the case of metal alloys.

Applications of AES and SAM are now legio and the selection will be a matter of taste. Rivibre chooses interesting examples from metallurgy, oxidation and material characterization mixed with good quality scan- ning electron microscopy micrographs.

Electron energy-loss spectroscopies including reflec- tion electron energy-loss spectroscopy, core electron

0168-583X/91/$03.50 0 1991 - Elsevier Science Publishers B.V. All rights reserved

Book review 587

energy-loss spectroscopy and high resolution electron difficulties in the quantification due to the complex energy-loss spectroscopy are introduced qualitatively behaviour of the ionization probability factor and ma- with a few formulae and many figures. In this chapter a trix effects. In secondary neutral mass spectrometry the single surface structural technique, extended energy- neutral particles, ejected as a result of ion bombard- loss fine structure, is included. Since a method for ment, are ionized and detected. Different setups are dete~ination of neighbouring distances is treated it discussed including photon ~stionization methods would have been more relevant, in terms of accuracy of where in the case of surface analysis by resonance the method and the number of users, to choose surface ionization of sputtered atoms detectabilities in the ppb extended X-ray absorption fine structure. range have been reached.

Chapters IO-12 deal with photon excitation; X-ray photoelectron spectroscopy (XPS) and X-ray Auger electron spectroscopy (XAES) get 50% of this part with a mainly qualitative introduction to the processing operation, again with useful comments for new people in the field. The theory section discusses line shapes, binding energy, chemical shifts and intensities. Some formulae are given but a detailed formulation must be found elsewhere [l]. Graphs of photoionization cross- sections as a function of atomic number, 2, for Al-& radiation catculated by Scofield and the asymmetry parameter in the differential photoelectron cross sec- tion as a function of Z are given. Concerning the quantification then the X-ray photoelectron current is treated in a manner analogous to that of the detected Auger current. Illustrative examples from the fields of corrosion/ passivation, catalysis and surface reactions demonstrate the great potential of this method and explain the extended use of XPS in many areas. As in the case of electron excitations relevant references are included up to 1985. One of the important aspects of ultraviolet photoelec~on spectroscopy (UPS), angle-re- solved UPS, is treated in Chapter 11 where also the advantage of using synchrotron radiation with the abil- ity to vary the photon energy provides an extra degree of freedom in the search of the band structure. This compensates for the stepchildlike review of syn- chrotron radiation in the instrumentation chapter.

The fast four chapters deal with complementary surface analytical techniques in the sense that they cannot be included under particle or photon excitation. Inelastic electron tunneling spectroscopy, field ion mi- croscopy and scanning tunneling microscopy/ spectroscopy (STM/STS) are rubricated as high field excitations. It is now eight years since Binnig and Rohrer invented STM and the method has been in rapid development since then. Diagrams of the princi- ple of operation and images clarify the basic content of this microscopy. The chemical information is not com- positional but electronic in terms of densities of filled and unfilled states near the surface.

The long journey in the fascinating world of surface analytical techniques finishes with a classical tech- nique, thermal desorption spectroscopy - still in good shape. It is able to inform about the nature of the products of reaction between the surface of a catalyst and adsorbing gases. Furthermore, the strength of the binding of the adsorbate and the adsorbate concentra- tion can be determined. The potential of the method, the dependence of the desorption peak shape on the order of the desorption reaction, and the examples are well described.

Ion excitation derived analytical techniques con- tribute, chapters 13-18, with a third of t.he volume dedicated to the three basic excitation mechanisms. Of the different ion scattering spectroscopies only ion surface scattering is chosen since it is surface-specific.

There are in all 461 figures distributed over 690 pages! In a way it reflects that we live in a world where pictures play an increasingly important role in commu- nication. It should be said that the figures are concise and informative. In one case, the Auger electron spec- trum of cadmium metal, the same figure is shown twice.

Some of the basic expressions for the kinematics in the scattering process are introduced under quantifica- tion but several of the definitions and the very instruc- tive diagram of the scattering process are first given in Chapter 18 under secondary ion mass spectrometry (SIMS). In fact, this is another example where basic concepts and definitions could have been concentrated in the introduction, Chapter 2. The third most widespread principal technique in surface analysis, SIMS, is the topic of Chapter 17. Both different types of apparatus and models are mentioned. In a clear way it is concluded that SIMS has advantages in terms of its high surface sensitivity for certain elements and molecules but the drawback of the method is the

In a monograph, references, and particulary refer- ence to reviews, are important. Most of the reference lists are of relevance. Dependent on the method, the lists end between 1985 and 1989.

ft would have been of value with a comparison, for example in the form of tables, of some of the most used methods in terms of criteria like element range, average detection limits, information depths, lateral resolution, compound information, destructiveness, matrix effects, etc. The properties of the different techniques are, of course, discussed in the respective chapters but a survey and an evaluation would be useful for readers who are not surface scientists.

The monograph on surface analytical techniques is an extensive presentation of the many methods avail- able for determining the composition of surfaces. In a

588 Book review

phenomenological and clear way it gives an instructive introduction. On the whole the author has succeeded in achieving a good survey of the many methods. It will be useful for students in surface science as a general handbook, but the high price will be a hindrance. As a text book in a surface physics course it needs comple- menting with other literature. The book is meant as an encyclopedia and is, as such, of relevance for a broad

spectrum of scientists in materials science, for manage- ment and for industrial laboratories.

Reference

[I] D. Briggs and M.P. Seah teds.), Practical Surface Analysis, Second edition, Vol. 1 (Wiley, New York, 1990).