SHAPE OF COLLISION BROADENED LINES FROM RESONANCE TO THE FAR WINGS

A line shape for collision-broadened lines applicable from the resonance region to the far wings is developed. An empirical correlation function is used to represent the known short and long time behavior of the true correlation function and to interpolate the unknown intermediate time regime. The resulting spectral shape is a simple analytic function which reduces to essentially the Van Vleck-Weisskopf equation when |ω-ω0|τ2≪1, but which smoothly assumes an exponential behavior in the far wings where |ω-ω0|τ2≫1. The time parameter, τ2, is a measure of the duration of collision and is related to the mean squared torque produced in bimolecular collisions. The effect of overlapping lines, also variations in the model correlation function on the line shape are considered. The theory is applied to the absorption in the high-frequency far wing of the 4.3υ band in CO2. © 1979.