The emission spectrum of the Li(2p)He2:12Πu exciplex

In order to understand the line broadening of the 2p → 2s transition of Li atoms in He gas as a function of pressure and temperature we have calculated the emission spectra of LiHe and LiHe2 based on quantum chemically computed potential energy surfaces and transition moment functions. A full quantum treatment of the red wing is compared with the results of simplified methods (e.g., the quasistatic theory) and with recent experiments.