MULTIPOLE TREATMENT OF RADIATION TRAPPING IN A STEPWISE-EXCITATION, ELECTRON-PHOTON COINCIDENCE EXPERIMENT

A theory is presented of radiation trapping effects in time-resolved, stepwise-excited, electron-photon coincidence signals. The theory is b ased on a detailed analysis of laser-induced optical pumping effects i n the stepwise excitation process combined with a multipole treatment of the radiation trapping processes. New data from a stepwise excitati on experiment on the inelastic excitation of the 6 P-1(1) state in e(- )-Hg collisions and previously reported data are compared with the pre dictions of the theory. Good agreement is found between experiment and theory, including confirmation that under some experimental condition s, the P-10 Stokes parameter of the coincidentally detected stepwise e xcited fluorescence increases in magnitude with increasing target gas density.