Study of momentum-transfer distributions in rotationally inelastic collisions ofCO2with foreign gas perturbers

An experimental technique utilizing the methods of laser saturation spectroscopy that enables a direct observation of the momentum transfer distribution generated by rotationally inelastic molecular collisions is presented. This method has been applied to ${\mathrm{CO}}_2$ in collision with a wide variety of partners including ${\mathrm{CO}}_2$, ${\mathrm{H}}_2$, Ne, ${\mathrm{NH}}_3$, and ${\mathrm{CH}}_3$F. The observations indicate that in a large number of cases the rotational transition results primarily from peripheral collisions which are effective in transferring angular momentum, but which communicate a relatively small linear momentum transfer.