Reorientational motion, collision-induced scattering, and vibrational relaxation in liquid carbonyl sulfide

Abstract

Articles you may be interested inThe effects of vibrational mode and collision energy on the reaction of formaldehyde cation with carbonyl sulfide Dynamics of molecular reorientational motion and vibrational relaxation in liquids. ChloroformThe rotational and vibrational behavior of neat liquid carbonyl sulfide under its own vapor pressure is investigated through Raman line shape studies of the symmetric v I C = S stretching mode over the temperature range T = 183 to 303 K. The reorientational motion is found to be near the diffusional limit. Various methods of determining the reorientational correlation time 'To are compared and their validity discussed. The contribution of collision-induced scattering to the v I mode rotational line shape is examined semiquantitatively. It is found that the relative contribution of collision-induced scattering to the overall rotational line shape increases with increasing temperature and decreasing density, whereas the second moment of the collision-induced line shape decreases. Assuming the separability of the collision-induced scattering contribution and the reorientational contribution to the observed line shape, the experimental data are discussed qualitatively in terms of the dipole-induced-dipole (DID) theory of Balucani and Vallauri. The vibrational relaxation mechanism for the v I mode is attributed to dephasing and interpreted by Kubo line shape theory. The dephasing is found to be in the "motionally narrowed" regime and discussed qualitatively in terms of attractive dipolar forces.

Separation of temperature and density effects on collision-induced Rayleigh and Raman line shapes of liquid carbon disulfide

“…:l value can be determined independently from the base The question posed is thus whether an acceptable value of n can be found where the signal to noise is large enough to provide a precise A value from the derivative function without sacrificing the accuracy of the A value obtained. In order to answer this question, we have taken derivatives of the anisotropic VI mode Raman line shapes of liquid OCS presented in an earlier publication 23 where the true base line was known. It was found that a reasonable range of n values did exist which could produce derivative functions that reproduced the true A values to within 10%.…”