The vibrational-translational energy transfer in binary mixtures: Influence of the vibrational mode close to the lowest mode in group relaxation

The energy transfer between vibrational and translational (V-T) degrees of freedom in the presence of a vibrational mode, which is close to an other v ibrational mode in another molecule, has been investigated. The ultrasonic velocities of bromoform-bromoform-d and chloroform-d-1,1,2-trichloroethane mixtures were measured in the frequency range from 100 MHz to 5 GHz by the three ultrasonic methods; high-resolution Bragg reflection, coherent Brillo uin scattering and Brillouin scattering. The velocity dispersions due to th e V-T energy transfer were observed in pure liquids and binary mixtures. Th e relaxation strength in the binary mixtures can be represented with the ad ditivity of relaxation strength with regard to the components. These result s indicate that the effect of the intermolecular vibrational-vibrational en ergy transfer on the V-T energy transfer is small.