Rubidium Spin Relaxation in the Rare Gases Under Ultraclean Conditions

Abstract

The spin relaxation of optically pumped rubidium vapor induced by rubidium-rare-gas atomic collisions has been investigated in an ultraclean environment. The experiment was performed under conditions such that the partial pressure of nonrare-gas impurities was less than 1×${10}^{-8\mathrm{}}$ Torr, and that the time between Rb-Rb spin exchange collisions was short compared to the spin relaxation time. The cross sections (in ${\mathrm{cm}}^2$) for disorientation of rubidium were found to be: He, 3.3×${10}^{-25\mathrm{}}$; Ne, 3.3×${10}^{-24\mathrm{}}$; Ar, 1.1×${10}^{-22\mathrm{}}$; Kr, 7.3×${10}^{-21\mathrm{}}$; Xe, 1.3×${10}^{-19\mathrm{}}$. The fact that these cross sections are considerably smaller than previously reported values is attributed primarily to the low degree of impurity contamination in the present work. When compared with already existing values for cesium and sodium, the disorientation cross sections of these three alkali metals are seen to have a remarkably similar dependence on buffer-gas atomic number. The new experimental values are also compared with recent theoretical calculations.