Raman study of pressure effects on frequencies and isotropic line shapes in liquid acetone

Abstract

The Raman line shape of the symmetric C = O stretching band at 1710 cm−1 has been measured in liquid acetone as a function of pressure from 1 bar to 4 kbar over the temperature range from −25 to 50 °C. The experimental data obtained show several unusual features. First, there is a frequency difference 〈δν〉 of about 7 cm−1 between the polarized and depolarized components. Sceond, the isotropic linewidth Γiso decreases with increasing density, in contrast to the opposite trend usually found in other liquids. Third, the second moment M2(V) of the isotropic band appears to decrease with increasing density. The consideration of the experimental linewidth and frequency data leads to a conclusion that intermolecular dipole–dipole coupling between polar acetone molecules are responsible for the observed unusual behavior of 〈δν〉, Γiso, and M2(V).