Infrared Sampling Methods

Abstract

Infrared spectroscopy has long been recognised as a powerful technique for obtaining structural information about molecules and for analysis. The traditional limitation of the technique was that samples had to be presented in a manner suitable for transmission of an infrared light beam, so that highly scattering or opaque samples were unsuitable. Thus a very wide range of scientifically and commercially important materials were precluded from study. Whilst transmission methods are still important today, and indeed are used by many spectroscopists as reference methods, newer techniques have become available which have widened the range of possible applications considerably. In this chapter three of these new methods: diffuse reflectance, attenuated total reflectance and photoacoustics are considered in addition to transmission methods. Together these methods represent those most widely used by spectroscopists and can, between them, produce spectra from samples in almost any physical form.