Broadening of Microwave Absorption Lines Due to Wall Collisions

Abstract

The broadening of microwave absorption lines due to wall collisions is calculated using a method introduced by Johnson and Strandberg. Two types of absorption cell are studied, i.e., infinite plane parallel plates and a circular cylinder, each in a region of uniform microwave field. The usual assumption that the half-power half-width is given by $\Delta \nu =\frac{1}{2\pi \tau }$, where $\tau$ is the mean time between collisions is in good agreement with the detailed calculations of the present work which show that the error in the line width as calculated by the above expression is not larger than 30 percent. Experimentally observed line widths agree with the predicted values.