Spin relaxation within the6P122and6S122states of cesium measured by white-light optical pumping

Collisional relaxation of spin polarization within the Cs atom has been studied using new techniques of white-light optical pumping. Analyses of pumping transient signals have been made including full treatments of effects due to the hyperfine interaction and spin exchange. The nuclear-spin-independent cross sections for relaxation of $〈S_z〉$ in the $6{}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}$ state of Cs, at 288 °K, are (in ${10}^{-23\mathrm{}}$ ${\mathrm{cm}}^2$): Cs-He, 2.43 ± 0.24; Cs-Ne, 4.08 ± 0.40; Cs-Ar, 108 ± 10; Cs-${\mathrm{N}}_2$, 55.2 ± 5.5. The nuclear-spin-independent cross sections for relaxation of $〈J_z〉$ within the $6{}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ state of Cs, at 288 °K, are (in units of ${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$): Cs-He, 12.5 ± 4.0; Cs-Ne, 6.9 ± 2.0. The Cs-buffer-gas diffusion coefficients, extrapolated to 273 °K, are (in units of ${\mathrm{cm}}^2$ ${\sec }^{-1\mathrm{}}$): Cs-He, 0.291 ± 0.030; Cs-Ne, 0.171 ± 0.017; Cs-Ar, 0.111 ± 0.011; Cs-${\mathrm{N}}_2$, 0.098 ± 0.010. There is no experimental evidence for contributions to low-pressure relaxation rates from the formation of Cs-buffer-gas van der Waals molecules, even in the case of Cs-Ar. There is, however, possible evidence for small contributions to relaxation rates at high buffer-gas pressures from this source.