Radiative Lifetime of the FirstP322State of Ionized Calcium and Magnesium by the Hanle Effect

Abstract

The lifetime of the ${\mathrm{Ca}}^{+}$ $4{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ state and that of the ${\mathrm{Mg}}^{+}$ $3{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ state have been measured by the Hanle-effect method with optical excitation from the ground states of the ions. The lifetimes are, respectively, (6.72±0.20)×${10}^{-9\mathrm{}}$ and (3.67±0.18)×${10}^{-9\mathrm{}}$ sec. The ions were produced by introducing traces of calcium or magnesium into an argon discharge. "Alignment" depolarization cross sections $\sigma$ were obtained for the collisional depolarization of the following states of calcium and magnesium due to collisions with argon: $\sigma \left(\mathrm{Ca} 4{}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{} \mathrm{state}\right)=(1.9\mathrm{}\pm 0.3)\times {10}^{-14\mathrm{}}{\mathrm{cm}}^2;$ $\sigma \left({\mathrm{Ca}}^{+} 4{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{} \mathrm{state}\right)=(1.4\mathrm{}\pm 0.2)\times {10}^{-14\mathrm{}}{\mathrm{cm}}^2;$ $\sigma \left(\mathrm{Mg} 3{}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{} \mathrm{state}\right)=(1.9\mathrm{}\pm 0.3){10}^{-14\mathrm{}}{\mathrm{cm}}^2;$ $\sigma \left({\mathrm{Mg}}^{+} 3{}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{} \mathrm{state}\right)=(1.3\mathrm{}\pm 0.25)\times {10}^{-14\mathrm{}}{\mathrm{cm}}^2.$