The development and application of new techniques in Fourier transform vibrational spectroscopy

A new technique for the reduction of fluorescence and its associated problems in Raman spectroscopy is presented, which makes use of a near infra-red Fourier Transform spectrometer and Nd:YAG laser excitation. Results are presented for the first time concerning the Surface Enhanced Raman spectrum of pyridine on silver, excited in the near infra-red. In addition, the Raman spectrum of polyvinylidene fluoride in both its α and β phases is given. These spectra have proved nearly impossible to obtain using conventional Raman techniques for reasons of fluorescence. A study of the vibrational behaviour of transition metal tetraoxo anions has been made using the Fourier Transform Raman technique and includes data of vastly higher quality than is currently available in the literature, notably for the deeply-coloured permanganate ion. The development of two sets of sampling optics for the Fourier Transform Raman spectrometer based on an ellipsoidal mirror and a lens pair is described in detail, together with the development of liquid sampling cells of different geometries. The use of a liquid nitrogen cooled sample holder is reported, as is the use of a spinning sample holder intended to reduce laser-induced heating of the sample. Background effects originating in fluorescence and in thermal emission are discussed and a tentative explanation for the observation of near-infrared excited fluorescence is presented.</p