Dephasing of molecular vibrations in liquids: Effects of molecular orientations and attraction

An equation for vibrational dephasing rates in liquids containing the effects of molecular orientations and attraction has been derived by use of the binary collision model. Dephasing rates are found to be a strong function of the orientation angle of vibrating molecules. For liquid nitrogen, the inclusion of oriented encounters leads to a slowing down of the dephasing rate by a factor of about three. Molecular attraction is found to enhance dephasing significantly.