Collisional Deactivation of H(22P) Fluorescence

Collision cross sections for deactivation of H*(n = 2) at 300°K have been measured by observations of the quenching of Lyman-α fluorescence in a discharge flow system. The quenchers (with cross section in Å2) are H2(84 ± 8), D2(84 ± 8), N2(62 ± 6), He(< 3). For H*+H2, less than 1% of the total quenching produces ions. Care has been taken to work with systems optically thin in Lyman α so that the rate of escape of radiation, which is the reference to which the quenching rate is compared, is not reduced by resonance trapping.