Integral cross sections for electron-impact ionization-excitation of laser-excited barium

摘要

We have measured electron-impact ionization-excitation (IE) cross sections for the Ba~+ (... 6p~2P) level out of the excited (... 6s5d~(1,3)D_(1,2)) and (... 6s6p~1P_1) levels of the neutral Ba atom in the energy range of 20-50 eV. Cross sections for IE out of the (... 6s6p~1P_1) level are approximately 50% larger than those from the (... 6s~(21)S_0) ground state, while cross sections for IE out of the D levels are approximately 50% that of IE out of the ground state. The dependence of these cross sections on the initial P state alignment has been found to be small.