Absolute Cross Sections for the Photoionization of He(n^{1,3}P) Atoms

Abstract

A molecular-beam apparatus is used in conjunction with a tunable laser to determine absolute cross sections for the photoionization of helium $3{}_{}{}^1{}_{}{}^{}P$, $4{}_{}{}^1{}_{}{}^{}P$, $5{}_{}{}^1{}_{}{}^{}P$, $3{}_{}{}^3{}_{}{}^{}P$, $4{}_{}{}^3{}_{}{}^{}P$, and $5{}_{}{}^3{}_{}{}^{}P$ atoms excited optically from the $2{}_{}{}^{1,3}{}_{}{}^{}S$ metastable levels. The photoionization cross section for each of these states is determined at the wavelength used for its excitation from the metastable state. The results are compared with those of recent unpublished calculations.