Effect of Exchange Forces on Rotational Lines Broadened by Rare Gases

A theory for the molecular collision cross section due to the exchange forces has been developed here following the Anderson—Tsao—Curnutte approach. The width of pure rotational lines of HCl broadened by rare gases has been theoretically calculated using the method developed here. The experimental and theoretical collision cross sections and half-intensity half-linewidths are compared, and in most cases they agree reasonably well.