Ebook: Modern Raman Spectroscopy – a practical approach

Since the first edition of our book, there has been a huge expansion in the use of
Raman spectroscopy. Advances in optics, electronics and data handling combined
with improvements made by manufacturers and spectroscopists have made Raman
scattering easier to record and more informative. Small, portable spectrometers are
rugged, reliable and are becoming less expensive. Some can work powered by lowvoltage
(1.5 V) batteries and give good performance in hostile environments. At the
other end of the scale, advanced equipment is simpler, more sensitive, more flexible
and more reliable. New methods with improved performance have been developed.
As a result, a technique which was once labelled by some as lacking sensitivity can
now, in the correct form, probe the electronic structure of a single molecule or be
used to help in the diagnosis of cancer. This has attracted many more users into the
field with a wide range of backgrounds.
Our aim in writing this book is to provide the understanding necessary to enable
new users to apply the technique effectively. In the early chapters we provide basic
theory and practical advice to enable the measurement and interpretation of Raman
spectra with the minimum barrier to getting started. However, for those with a deeper
understanding of the effect, Raman scattering is a very rich technique capable
of providing unique information and a unique insight into specific problems. In
writing this book some difficult choices have had to be made around the presentation
of the theory, particularly with the wide variety of backgrounds we expect
readers to possess. We have used as few equations as possible to show how the
theory is developed and those are deliberately placed after the chapters on basic
understanding. We concentrate on molecular polarizability, the molecular property
which controls intensity. The equations are explained, not derived, so that those with
little knowledge of mathematics can understand the conclusions reached and those
of a more mathematical bent can use the framework for further investigation. This
enables selection rules, resonance Raman scattering and some of the language in
modern literature to be understood. This is not the traditional approach but, although
deriving scattering theory from first principles is good for understanding, it adds little
to Raman interpretation. Classical theory which does not use quantum mechanics
cannot deliver the information required by most Raman spectroscopists. For these
reasons, references to these areas are given but the theory is not explained.