Multipole treatment of radiation trapping in a stepwise-excitation, electron-photon coincidence experiment.

Abstract

A theory is presented of radiation trapping effects in time-resolved, stepwise-excited, electron-photon coincidence signals. The theory is based on a detailed analysis of laser-induced optical pumping effects in the stepwise excitation process combined with a multipole treatment of the radiation trapping processes. New data from a stepwise excitation experiment on the inelastic excitation of the 6${\mathrm{}}^{1}$${\mathit{P}}_{1}$ state in ${\mathit{e}}^{\mathrm{\ensuremath{-}}}$-Hg collisions and previously reported data are compared with the predictions of the theory. Good agreement is found between experiment and theory, including confirmation that under some experimental conditions, the ${\mathit{P}}_{10}$ Stokes parameter of the coincidentally detected stepwise excited fluorescence increases in magnitude with increasing target gas density. \textcopyright{} 1996 The American Physical Society.