Infrared and Raman spectrometric detectors

A Fourier transform infrared spectrometer consists of an infrared source, an interference modulator (usually a scanning Michelson interferometer), a sample chamber and an infrared detector. Interference 

The principal reasons for choosing Fourier transform infrared spectroscopy are first, that these instruments record all wavelengths simultaneously eind thus operate with maximum efficiency and, second, that they have a more convenient optical geometry than do dispersive infrared instruments. These two facts lead to the following advantages. 

Conventional Raman spectroscopy cannot be applied directly to aqueous extracts of sediments and soils, although it is occasionally used to provide information on organic solvent extracts of such samples. Fourier transform Raman spectroscopy, on the other hand, can be directly applied to water samples. The technique complements infrared spectroscopy in that some functional groups, eg unsaturation, give a much stronger response in the infrared. Severed meinufacturers (Perkin-Elmer, Digilab, Bruker) now supply Fourier transform infrared spectrometers. 

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