Measurements of Cesium Cold-Collision Cross-Sections

Alan C. Gallagher

The cross sections for rubidium $5^{2}P_{\frac{1}{2}}\ensuremath{\rightleftarrows}5^{2}P_{\frac{3}{2}}$ and cesium $6^{2}P_{\frac{1}{2}}\ensuremath{\rightleftarrows}6^{2}P_{\frac{3}{2}}$ excitation transfer due to inert-gas collisions have been measured. The temperature of the collision vessel has been varied from 300\ifmmode^\circ\else\textdegree\fi{}K to 900\ifmmode^\circ\else\textdegree\fi{}K in order to partially establish the velocity dependence of these cross sections (the alkali resonance-line optical depths were always much less than 1). The various cross sections exhibit a systematic behavior that can be combined to find the general shape of a "universal" cross section that ranges across six orders of magnitude, starting just below the threshold for "sudden" collisions. The surprisingly large influence of optical line broadening on these excitation-transfer measurements has been removed as a source of error.

D. M. B. P. Milori, A M Tuboy, José Roberto Garbin +1 more

Paul W. Pace, J. B. Atkinson

The method of sensitized fluorescence has been employed to investigate the [Formula: see text] excitation transfer processes in cesium induced in collisions with ground state cesium atoms. The cesium vapor density was kept sufficiently low to enable the cross sections for the mixing process to be determined under single collision conditions and to ensure that radiation trapping and quenching were negligible. A nitrogen laser pumped dye laser was used to excite the cesium atoms to each of the 72P levels in turn and measurements of the relative intensities of fluorescence yielded the following cross sections: [Formula: see text] These results are consistent with the empirical relationship between the magnitude of the cross sections and the fine structure splitting that has previously been determined for the alkalis.

A. Fioretti, E. Arimondo, A. Crubellier

J. Weiner

I. N. Siara, H. S. Kwong, L. Krause

The cross sections for 72P1/2–72P3/2 excitation transfer in cesium, induced in collisions with noble gas atoms, have been determined in a series of sensitized fluorescence experiments at temperatures ranging from 405 to 630 K. The cross sections which lie in the range 0.06–20 Å2, exhibit a temperature dependence which, however, is less pronounced than in the more adiabatic case of the cesium resonance doublet.