Narrow Hyperfine Absorption Lines ofCs133in Various Buffer Gases

Abstract
Line widths as narrow as 40 cps have been obtained for the hyperfine transition at 9192 Mc/sec in cesium vapor. The Doppler width was greatly reduced by collisions with an inert buffer gas. An optical detection method was used to observe the microwave absorption lines. Shifts in the observed frequency due to collisions with the buffer gas were measured as a function of the temperature and pressure of the gas. It was found possible to reduce greatly the shift in frequency with temperature by using the proper mixtures of inert gases. The contribution to line width due to collisions with the buffer gas was also determined.