Nuclear-Spin Inertia and Pressure Broadening ofP122Hanle-Effect Signals

Hanle-effect measurements yield values for the collisional depolarization rates of ${}_{}{}^2{}_{}{}^{}P_{\frac{1}{2}}^{}{}_{}{}^{}$ excited atomic states that are about three times too small unless one explicitly includes the effects of nuclear spin. The broadening also becomes a nonlinear function of foreign-gas pressure. We present experimental evidence for nuclear-spin effects on pressure-broadened Hanle-effect signals of ${\mathrm{Rb}}^{85}$ and ${\mathrm{Rb}}^{87}$ in helium.