Study of the Raman non-coincidence effect from methyl formate acetonitrile solutions

The Raman non-coincidence effect (NCE) of the carbonyl stretching band of methyl formate diluted in acetonitrile was studied. The observed NCE was compared with the predictions of a number of models for non-isotopic dilutions. All of the models failed. Thermodynamic data indicate that the mixtures are very nearly ideal. The failures of the models, therefore, cannot be solely ascribed to the assumption of solution ideality. The carbonyl bandwidths were also measured and their behaviour was unusual (first increasing and then decreasing), although consistent with previous findings for isotopic dilutions. (C) 1998 John Wiley & Sons, Ltd.