Physical Review A
Resonance broadening of Hanle-effect signals in rubidium
Alan C. Gallagher, E L Lewis
Abstract
We have measured the broadening of ${\mathrm{Rb}}^{87}$ level-crossing signals due to collisions with ${\mathrm{Rb}}^{85}$. The depolarization or broadening rates for the $5^{2}P_{\frac{1}{2}}$ state orientation, the $5^{2}P_{\frac{3}{2}}$ state orientation and alignment, and the $5^{2}P_{\frac{3}{2}}$ state 58-G crossing were measured. Theoretical resonance-broadening depolarization rates for the electronic angular momentum, due to Carrington, Stacey, and Cooper, have been incorporated into calculations of the Hanle-effect signals in the presence of nuclear-spin coupling. The experimental broadening rates are corrected for a minor amount of coherence narrowing. The measured broadening rate for the three $5^{2}P_{\frac{3}{2}}$ state level-crossing signals are in 20% agreement with the theory. The measured $5^{2}P_{\frac{1}{2}}$ state broadening rate exceeds the theoretical by about a factor of 2. This discrepancy may be due to the action of the hyperfine interaction during these unusually long duration collisions. The natural lifetimes of the $5^{2}P_{\frac{3}{2}}$ and $5^{2}P_{\frac{1}{2}}$ states are determined from the low-density linewidth to be 27.0 \ifmmode\pm\else\textpm\fi{} 0.5 and 29.4 \ifmmode\pm\else\textpm\fi{} 0.7 nsec, respectively.