Mean square torques and correlation functions of the ν3 vibration of N2O mixed in argon at variable temperature

The second and fourth spectral moments of the ν3 vibration of N2O mixed in compressed argon are reported for five temperatures. The ratio of the mean square torque to the density is deduced and it is found to increase with the temperature, thus showing the major role of the repulsive potential in the formation of the torque. Comparison of experimental correlation functions with models shows that the assumption of instantaneous collisions is too crude. The Steele memory function theory yields instead a satisfactory agreement with the experimental data.