Abstract
A method for measuring very small shifts in the position of Raman bands in FT Raman spectra is presented. This centres on band fitting calculations, with mixtures of acetone H 6 and acetone D 6 being used as a trial system. Different cell designs were used, the best results being obtained from a cuvette where anomalous shifts from variations in sample position were eliminated. Linear shifts were found in the CH, CD and CC stretching bands as a function of the molar composition of the sample. The CH and CD bands were also found to narrow in addition to shifting. Synthetic spectra were generated to investigate the effect of noise on the calculation and these indicate that a signal-to-noise ratio of 20 is sufficient to observe shifts of the order of 0.1 cm −1. Plasma emission lines from the laser can be used as an internal frequency standard, thus allowing the method to be applied to solid samples.
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