Picosecond Dephasing of Coherently Excited Vibrations in LiquidN2-Ar Mixtures

Vibrational-dephasing times have been measured in mixtures of liquid ${\mathrm{N}}_2$ and Ar. The correlation time of the molecular motion initiating the dephasing process is calculated to be 2.2 and 4.6 ps in pure ${\mathrm{N}}_2$ and pure Ar, respectively. These rather long correlation times suggest that the dephasing results from the average force field determined by the number of nearest-neighbor molecules.