close

Вход

Забыли?

вход по аккаунту

?

Book Review Symmetry through the Eyes of a Chemist. By I. Hargittai and M. Hargittai

код для вставкиСкачать
second, the examples chosen are kept very simple and are
therefore not of much interest to the chemist who is more
concerned with complex substances and structures.
There is quite obviously a gap here, which the present
book, derived from a series of lectures to advanced students at the University of Oxford, sets out to fill. In its
conception it follows in the steps of the now rather dated
“Seven Solid States” by W. J. Moore, which in its time familiarized chemists with basic solid state physics, using
suitably chosen compounds as examples.
In the first three chapters of the book, basic concepts
such as bonding situations in crystals, the free electron gas
and optical processes are treated qualitatively and without
giving mathematical derivations, illustrated by appropriate
examples. Some spectroscopic techniques are outlined as
well, with particular emphasis on photoelectron spectrosCOPY.
The remaining four chapters deal with special topics. An
entire chapter is devoted to a “formal” introduction to energy band theory. The concepts needed for the analysis of
band structures are worked through with the help of diagrams, without giving involved mathematical derivations,
and are tested on simple examples such as graphite and
ReO,. This is followed by a short account of the experimental determination of band structures using angularly
resolved photoemission spectroscopy. Two further chapters deal with electron repulsion effects in terms of the
Hubbard model, and with lattice distortions and mixed
valency compounds. The final chapter is concerned with
semiconductors and their uses in photovoltaic cells, transistors etc.
Altogether the conception of the book and the way in
which it has been put together make it a useful addition to
the literature. The material is arranged in a clear manner,
and the individual sections are lucidly written and illustrated by many well chosen examples. Some of the topics
are discussed only briefly, but one cannot expect a book of
250 pages to cover every topic of current research in detail.
The material included has been well chosen. The references to more detailed review articles and original papers
which are included, with comments, at the end of each
chapter give the interested reader easy access to further
reading, and a short formula index included at the end of
the book helps in locating compounds cited as examples.
In summary, the author P. A . Cox has brought considerable skill to the task of familiarizing chemists with the electronic structure of solids. At the very attractive price of
-E 12.50 in its paperback edition, the book is certainly a
worthwhile and useful aid to advanced students and to
synthetic chemists.
Wolfgang Tremel [NB 871 IE]
Anorganisch-chemisches Institut
der Universitat Miinster (FRG)
Symmetry through the Eyes of a Chemist. By I. Hargittai
and M . Hargittai. VCH Verlagsgesellschaft, Weinheim
1986. xii, 458 pp., bound, DM 156.00.-ISBN 3-52726409-4
I spent the years 1950-51 in Linus Pauiing’s group at the
California Institute of Technology, which was then one of
a mere handful of Meccas for theoretical chemists. TOgether with Sidney Weinbaum of HT fame (he was-to my
knowledge-the first to use an extended basis in a MOcalculation), I was assigned the task of calculating carbon
clusters C, by the then popular valence bond method. We
720
met our Waterloo as soon as we reached the cubical CH
cluster, not knowing how to factorize the general eigenvalue problem of order 14 into manageable parts. (Those
were still the days of the B.C. era, i.e. before computers,
even at Caltech.) There was nothing to be ashamed of,
since we were in the best of company in our lack of knowledge. Indeed, even in most books on quantum chemistry
written for “real” chemists, group theory was conspicuous
by its absence. Even in Streitwieser’s classic on MO theory
written in 1961, symmetry considerations play at best only
a Cinderella role.
The situation has changed dramatically since those days.
The enormous growth in the use of physical methods, especially spectroscopy, the wide application of quantum
mechanics and of a new chemical language derived from
it, and the discussion of reaction mechanisms and stereochemical problems in terms of symmetry, have led to a
rapid increase of interest in symmetry and group theory.
Chemists changed their outlook and began to collect
Escher prints, and publishers started to outbid each other
in producing introductions to these new fields. One consequence of this is that there is now scarcely a single library
which owns a more than half complete collection of all
books relating to this area, ranging from advanced mathematical works to those of a popular scientific type. Every
newly published book on this theme must therefore be
judged against this background of an overabundance of related literature which already exists.
The first thing which strikes one about the book reviewed here is its exorbitant price: a princely DM 156.for a book which is presumably intended as an introduction. One might therefore ask why the book is so highly
priced, and whether this could not have been avoided. One
cause of this is a use of space which could scarcely be rivalled in its extravagance. With an approximate page format of 24 cm x 17 cm=408 cm2, the print area is only
about 21 cm x 9 cm = 189 cm’. Admittedly the extremely
wide margin-about double the usual width-is partly
used for figure legends, but these generally only contain
information on the sources for the figures, e.g. the caption
“Photograph by the authors”, which is repeated about 40
times. The 421 literature references occupy three times as
much space as they would in other books, owing to the
very large gaps between individual references, allowing
only 15 to a page. In addition the number of examples included is wastefully large, many of them scarcely adding
anything to the understanding of the material. Or d o you
believe that the concept of antisymmetry will be made significantly clearer to a novice by having before him a picture showing a McDonald’s adjacent to a more up-market
restaurant? (“Photograph by the authors”). Likewise
“Eszter Hargittai in front of a shop window (1980) (“Photograph by the authors”) makes only a minimal contribution to the understanding of mirror symmetry. Altogether
one gets the impression that the authors have tried, in their
understandable enthusiasm for the subject, to include in
this book every quotation related to symmetry which they
have collected over the years. As a result there are loilg
sections which are more like a family album of personal
recollections than a guide through the subject written with
the object of instructing the reader. Further, the information content is sometimes appallingly thinly spread. For
example, seven pages are needed to explain what a matrix
is and how two matrices are multiplied, and ten pages to
discuss the symmetry properties of the HMOs in benzene.
Dietrich Stauffer, in his excellent and wittily written book
“Introduction to Percolation Theory”, writes: “YOU may
Angew. Cliem. Inr. Ed. Engl. 27 /19XX/ N o . 8
complain that the square lattice in Figure 1 (a) is not very
large, but the publishers did not allow me to fill the remaining pages of this book with these squares, ...”. One
wishes that the authors of the present book had been given
similarly valuable advice by the publishers, so that its
length-and presumably its price-could have been reduced without difficulty by at least one third, with no sacrifice of information and with a rather more sensible
layout.
When we ask the question for whom this book was written, we find that the potential reader must have a very
strange, contradictory make-up. It is evidently assumed
that he has no knowledge whatsoever of the most elementary matrix operations, nor has he heard of symmetry or
crystallography, let alone of group theory, all of which are
nowadays obligatory topics in the first semesters of a
chemistry course. Is it then a book for the interested layman? By no means! The reader must not only have mastered the formal language of chemistry in all its subtleties,
and have a thorough knowledge of much of stereochemistry, in order to understand the significance of the examples, many of which are quite advanced. In addition, this
reader, who has just encountered matrices and the simplest
types of symmetry considerations for the first time in his
life a few pages earlier, must without any previous experience be able to understand and use the operator formalism
of the Schrodinger equation, and-without any detailed
explanation-be familiar with all relevant concepts of
quantum mechanics and molecular orbital theory. In other
words, the book is neither fish nor fowl. For the chemistry
student who has not been asleep during the first semesters,
and who has obtained his knowledge of physical chemistry
from a modern book such as the best-selling “Physical
Chemistry” by P. W. Atkins, some long sections of this
work will seem trivial. For the non-chemist, on the other
hand, it assumes far too much knowledge, and it is especially at fault in explaining quite simple points at great
length, whereas those steps which present real difficulties
for the layman are just glossed over. Admittedly, for the
reader who already has the necessary previous knowledge,
and is interested in the ramifications of symmetry considerations both within and outside chemistry, the book is a
fascinating, if over-priced, mine of information, which deserved to be written in a more concise form. The virtually
exhaustive bibliography, and the (overfgenerous selection
of examples mentioned earlier, make the book a welcome
and useful work of reference for everyone who is seriously
involved in teaching the application of symmetry concepts
and has so far neglected those aspects not directly related
to chemistry. On the other hand, anyone who has already
concerned himself with such ideas will get a definite “deja
vu” feeling throughout large sections of the book. Thus it
seems worth mentioning that most of the illustrations from
art, biology and other fields can be found, for example, at
a cost of only DM 40.--, and partly in color, in the excellent, 466-page first volume of the exhibition catalog “Symmetry in Art, Nature and Science” of the Mathildenhohe
in Darmstadt. (Volumes 2 and 3 contain further examples).
However, the publishers, VCH Verlagsgesellschaft, take
the view that this book has been written expressly for students. In fact, the same publishers’ German translation
(“Physikalische Chemie”) of the excellent book by P. W.
Atkins mentioned earlier contains an unexpected innovation: whereas in the original English version the references
given for further reading following the chapter on symmetry are to classic works such as Hermann W e d ’ s “SymmeAngew. Chem. Inr. Ed. Engl. 27/1988) No. 5
trie” and the well-known books by Jaffe, Orchin, and by
Cotton, we now find that all these have been deleted from
the German edition and replaced by a full-page advertisement for the book reviewed here!
The following quotation is offered to the authors as consolation: “The writer has collected his material together
most diligently, and no discovery of importance which became known during the preparation of the work has been
omitted. Our only regret is that he tells us indiscriminately
and in immense detail everything which he has learned,
and thereby unnecessarily increases the cost of his
book.”-From the 1831 review of the German translation,
still well known even today, of the textbook by Louis
Jacques ThPnard (Neues Journal der Pharmacie 22 ( 1831)
276).
Edgar Heilbronner [NB 882 IE]
Physikalisch-chemisches Institut
der Universitat Basel (Switzerland)
Lasers in Chemistry. Von D. L. Andrews. Springer, Berlin
1986. xii, 176 pp., broschiert, D M 68.00.-ISBN 3-54016161-9
This book with its just 163 pages may be looked upon as
a very compact text addressing both the scientist with general interest and the undergraduate student. It is, however,
by no means useless to the more advanced reader. It even
impresses the reader by the wealth of laser applications
mentioned, ranging out to such specialized topics as ceramic powder formation or cancer therapy by lasers. Its
general attitude is very positive with regard to the uses of
lasers in chemistry and high hopes for the future are expressed. The diligence and the depth of treatment must be
viewed differently for the different chapters.
In chapters 1 and 2 attempts are made to provide an introduction into the physics (18 pages) and into the technology (25 pages) of lasers. Doubts are justified if this is really
helpful (e.g. one page on the free electron laser). Perhaps
the chemist user would benefit more from a simple table of
common commercial lasers and their typical performance
data. Such a user-oriented survey is indeed provided on
page 164, although in rather short form. The strength of
the book in the opinion of the referee lies in chapters 3
(Laser Instrumentation in Chemistry) and 4 (Chemical
Spectroscopy with Lasers). Especially chapter 4 gives a fair
summary of most of the important laser analytic methods
in a systematic way. The treatment ranges from specialized
absorption techniques over fluorescence and Raman spectroscopies to multiphoton processes and laser mass spectrometry. In the last chapter (Laser Induced Chemistry),
which in the preface is said to be most promising among
the different laser applications, the following topics are
considered: Infrared multiphoton excitation, isotope separation, unimolecular laser induced and bimolecular laser
enhanced reactions and-on three pages-surface chemistry with lasers as well as-also very briefly-psec phenomena. This treatment cannot d o justice to the laser o r to the
field of chemical dynamics as such. Lasers are very special
energy sources with their combined properties of coherence, high radiation intensity, ultrashort pulses and extreme monochromaticity. Their potential in chemistry cannot easily be realized by traditional chemical thinking and
in the language of preparative chemistry. Besides, it should
be mentioned that the main success of laser chemistry at
present is not so much in synthetic chemistry than in materials research and processing. This is not adequately cov72 1
Документ
Категория
Без категории
Просмотров
0
Размер файла
299 Кб
Теги
symmetry, chemists, book, review, eyes, hargittai
1/--страниц
Пожаловаться на содержимое документа