Quenching of Cesium Resonance Radiation by Helium

Abstract

Using the phase‐shift technique to measure excited‐state lifetimes, upper limits of 1.5 × 10⁻¹⁴ cm³/sec and 3 × 10⁻¹⁴ cm³/sec have been established for the $\mathrm{Cs}{\text{(6}}^2{P}_{\text{1/2}}{\mathrm{re}}_{\text{3/2}}\mathrm{)\hspace{0.17em}+\hspace{0.17em}}\mathrm{He}\mathrm{\hspace{0.17em}\to \hspace{0.17em}}\mathrm{Cs}{\text{(6}}^2{S}_{\text{1/2}}\mathrm{)\hspace{0.17em}+\hspace{0.17em}}\mathrm{He}$ quenching rate constants at 350° and 820°K. (In “cross‐section” units these are equivalent to 10⁻¹⁹ cm² upper limits.) The natural lifetimes were measured to be 30.8 ± 1.5 × 10⁻⁹ sec and 35.2 ± 1.5 × 10⁻⁹ sec for the $\mathrm{Cs}{6}^2{P}_{\text{3/2}}$ and $6^2{P}_{\text{1/2}}$ states.