Combined Doppler and Collision Broadening*

Abstract

The combined effect of Doppler and collision broadening of spectral lines is studied by means of the statistical correlation function for the time-varying amplitude of classical oscillators. It is shown that at high pressures (mean-free path smaller than wavelength) the line shape is lorentzian with a width which is the sum of the conventional collision broadening and a Doppler contribution which decreases with increasing pressure, consistent with Dicke’s result.