Spectroscopic studies of solute–solute and solute–solvent interactions in solutions containing N,N-dimethylformamide

Abstract

Infrared, far-infrared and Raman spectra of N,N-dimethylformamide are reported for the liquid and across the whole concentration range in carbon tetrachloride solution. The data reflect important differences between the long-ranged and short-ranged behaviour of the solute–solute and solute–solvent intermolecular potentials. In particular, the far-infrared spectrum is dominated by short-ranged interactions which vary only marginally with concentration and which are probably controlled by geometrical factors. On the other hand, the Raman and infrared band shapes are drastically affected by at least two types of dephasing process, including resonance energy transfer and the effects of concentration fluctuations, both probably mediated through strong longer ranged dipolar interactions. Molecular tumbling motion is severely hindered in the liquid and gets faster on dilution, presumably owing to the removal of intermolecular correlations.