Temperature Dependence of the Electron-Rubidium Spin-Exchange Cross Section

Abstract

A spin-exchange optical-pumping experiment to study the temperature dependence of the electron-rubidium spin-exchange cross section is reported. In this experiment, electrons were polarized in a weak magnetic field by spin-exchange collisions with optically pumped Rb atoms. The electron-Rb collisions were the principal source of the electron-spin-resonance linewidth, and they also produced a shift in the resonance frequency. The magnitudes of the linewidth and frequency shift are functions of the electron-Rb-scattering phase shifts. The electron linewidth at fixed Rb density was essentially constant over the temperature range 200-840 \ifmmode^\circ\else\textdegree\fi{}K indicating the spin-exchange cross section is well approximated by a $\frac{1}{v}$ velocity dependence. The ratio of the frequency shift to linewidth was 0.075\ifmmode\pm\else\textpm\fi{}0.005 at 300 \ifmmode^\circ\else\textdegree\fi{}K with an estimated Rb polarization of (20\ifmmode\pm\else\textpm\fi{}10)%, and the ratio was 0.027\ifmmode\pm\else\textpm\fi{}0.007 at 600 \ifmmode^\circ\else\textdegree\fi{}K with a Rb polarization of (10\ifmmode\pm\else\textpm\fi{}5)%.