Deexcitation of He RydbergSand manifold states byN2

Abstract

The quenching cross sections for the He $2S-9S$, $3{}_{}{}^1{}_{}{}^{}P$, and $n=5-9\mathrm{}$ manifold states by ${\mathrm{N}}_2$, and $n=6-9\mathrm{}$ manifold states by He, Ar, and Kr have been measured at 600 K. The cross section for $2 {}_{}{}^3{}_{}{}^{}S$ by ${\mathrm{N}}_2$ is 7.9(+1.2,-0.7) ${\mathrm{\AA }}^2$, and the values obtained for $\mathrm{nS}-{\mathrm{N}}_2 (n\ge 3)$ are 40-80 ${\mathrm{\AA }}^2$ and increase slowly with $n$ up to $n=5\mathrm{}$ then show a plateau or decrease slightly with $n$. The cross sections for the ${}_{}{}^1{}_{}{}^{}S$ are about 1.3 times those for the ${}_{}{}^3{}_{}{}^{}S$ for $n=3\mathrm{} \mathrm{and} 5$. The cross sections for the $n=5,8, \mathrm{and} 9$ manifold states by ${\mathrm{N}}_2$ are nearly the same in magnitude as those for $S$ states; however, those for rare-gas collisions are about one order smaller than those for ${\mathrm{N}}_2$ collisions. The main mechanism for the quenching of He Rydberg states ($n\ge 3$) by ${\mathrm{N}}_2$ is attributed to $n$-changing collisions due to excitation of molecular vibrations in ${\mathrm{N}}_2$.