Lifetime of the1s2(P11)and1s4(P13)levels of neon by the cascade Hanle effect

The theory of the cascade level-crossing effect as formulated by Happer is evaluated for zero-nuclear-spin atomic systems and extended to include the case of a polarized initial state. We have used this theory to interpret our cascade-Hanle-effect results (zero-field level crossings) to obtain the lifetime of the two resonance levels, $1s_2\left({}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}\right)$ and $1s_4\left({}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}\right)$, of the $2p^{5}3s$ configuration of neon. The resonance lines 744 Å ($1s_4-{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$) and 736 Å ($1s_2-{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$) are produced in the cascade to the ground ${}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ state when a beam of metastable $1s_3\left({}_{}{}^3{}_{}{}^{}P_0^{}{}_{}{}^{}\right)$ and $1s_5\left({}_{}{}^3{}_{}{}^{}P_2^{}{}_{}{}^{}\right)$ neon atoms is excited by selected lines of the $2p^{5}3s-2p^{5}3p$ transition array. Our results are $\tau \left(1\mathrm{}{s}_2\right)=1.65\mathrm{}\pm 0.16$ nsec and $\tau \left(1\mathrm{}{s}_4\right)=20.5\mathrm{}\pm 1.5$ nsec.