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Book Review Unimolecular Reactions. Second edition. By K. A. Holbrook M. J. Pilling and S. H

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stants, neither of which is discussed in the
book, may often be possible in principle,
but is usually not the most efficient approach. Also some important older and
well-established techniques, such as spin
decoupling, are not discussed. A more
honest title for the book would be something like “Modern N M R Spectroscopic
Techniques” .
The inclusion of exercise problems with
answers in each chapter is a welcome feature. Unfortunately, however, the questions posed are not always very useful
from a learning standpoint (example:
“The signal-to-noise ratio can be increased by [applying] proper apodization
functions. What would happen without
apodization?”), and occasionally they
suggest a whimsical attitude on the part of
the authors. For example, to the question
of what type of probe-head is most suitable for a group of preparative chemists
where the problem of insufficient sample
does not arise. the answer given is “a
probe-head for 10-15 mm sample tubes”.
The book’s most serious shortcoming is
that many of the figures are of very poor
quality. This applies especially to the reproduction of spectra, a few of which have
obviously been drawn by hand. Many of
the 2D spectra are much too small. Occasionally the one-dimensional spectrum is
missing from one of the axes, or is shown
on such a small scale that only methyl
group singlets are adequately reproduced
(4 mm height!), with the result that no
coupling multiplets can be recognized,
since they would only be a fraction of a
millimeter in height. This happens even on
pages whose space is not fully used. The
book would have been much improved by
using a larger format and taking greater
care with the layout. It needs to be thoroughly reworked.
Ludger Ernst
NMR-Laboratorium
der Chemischen Institute
der Technischen Universitat
Braunschweig
Braunschweig (Germany)
Kerstin Ibrom
Konigstein im Taunus (Germany)
Angew Chem. Ii i l Ed Engl. 19%. 35, N o 19
Unimolecular Reactions. Second edition. By K. A . Holbrook, M . J. Pilling
and S. H. Robertson. Wiley, ChiChester, 1996. 417 pp., hardcover
.€ 90.00.-ISBN 0-471-92268-4
The subject of unimolecular reactions
has undergone much development in the
last few decades. Many new types of experiments have been carried out, affording insights that could scarcely have been
imagined 30 years ago. It has become possible to make remarkably precise measurements on reactions of practical importance. Alongside these advances,
theoretical methods now allow one to analyze the fundamental processes with improving quantitative reliability. Consequently, monographs and review articles
dealing with this fast-moving field soon
become outdated. It is therefore very
pleasing that K. A. Holbrook, M.J.
Pilling, and S. H. Robertson have now
produced a thoroughly revised and significantly enlarged new edition of Unimolecular Reactions, first published in 1972 under the authorship of P. J. Robinson and
K. A. Holbrook. In that first edition,
“Robinson and Holbrook” contained an
excellent introduction to the application
of the H R R K M theory, the statistical
theory of unimolecular reactions developed by Hinshelwood, Rice, Ramsperger,
Kassel, and Marcus, together with a
detailed compilation of experimental
data on classical reactions. At that time
this was the most detailed introduction to the practical application of the
R R K M theory available in the literature. However, in recent years it had become seriously outdated because the
many later developments were not covered.
Thermal and nonthermal unimolecular
reactions are often studied under conditions in which the reaction rate is determined solely o r partly by intermolecular
energy exchange through collisions. In
retrospect it seems surprising that for
many years the details of this process received so little attention. The new edition
of this book remedies that omission by
including descriptions based on the fundamental equations. Nevertheless, perhaps an even more detailed treatment of
the energy transfer process would have
conveyed a better understanding of its
characteristics.
The new numerical algorithms for calculating densities of states and numbers of
states are treated in detail in this book,
so that the statistical analyses of the
R R K M theory can be carried to completion. Thus, even a beginner should have
no difficulty in learning how to treat reac-
0 VCH Verlugsgesellschuft mhH. 0.69451
Wemherm. 1996
tions involving rigid activated complexes,
for which the classical R R K M theory was
mainly developed. The new edition also
includes a detailed treatment of reactions
involving nonrigid activated complexes.
The description and comparison of the
different variants of theoretical treatments of the transition state is excellent
and useful. In view of this it is even more
surprising that the phase space theory,
which represents the limiting case of completely flexible transition states, and
makes it easy to correctly take into account the conservation of angular momentum in the reaction, is almost completely ignored. To have included a
treatment of this limiting case would have
helped the reader to understand the detailed description of the statistical adiabatic channel model.
The book contains a wealth of information about current experimental and theoretical studies in this field. The descriptions of the kinds of investigations now
possible are illustrated by informative examples, thus providing the beginner with
an excellent introduction and the more
advanced researcher with many stimulating ideas. It retains the spirit of the original “Robinson and Holbrook”, while also
bringing the treatment up to date. If the
book had been completely rewritten from
the start, there would probably have been
some changes of emphasis. It would then
have been possible to devote more space
to topics such as the breakdown of molecular ions, bimolecular complex-forming
reactions of neutral or charged species,
trajectory calculations, calculations of
adiabatic channel potentials made possible by the latest methods, anharmonic
densities of states, and (as already mentioned above) phase space theory. At the
same time the treatment of the classical
R R K M theory could be shortened. However, to do so would have resulted in a
more bulky monograph than intended.
Therefore the changes have been limited
to a very successful updating of the original concept. The book is well suited as a
text for further reading by advanced students, and will also serve the needs of reaction kineticists who intend to work on
gas phase reactions.
Jurgen Troe
Institut fur Physikalische Chemie
der Universitat Gottingen (Germany)
0570-0833196/35I9-2267 $15.00+ .25/0
2267
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