Absolute photoionization cross sections of the Cs 7D3/2 level measured by use of fluorescence reduction.

Abstract

A simple technique for measuring absolute photoionization cross sections \ensuremath{\sigma} of excited atoms has been applied to the 7${D}_{3/2}$ level in Cs. Past experiments on excited-state cross sections have relied on measurements of the total number of ions or photoelectrons produced by photoionization to deduce \ensuremath{\sigma}. Our technique is novel in that it utilizes the simple measurement of the reduction in the excited-atom fluorescence due to photoionization to find \ensuremath{\sigma}. We report measurements of cross sections at six different photon energies.