Velocity Relaxation of Fast Hydrogen Atoms by Collisions with Rare Gases, N2, O2, and N2O

초록

Velocity relaxation of fast hydrogen atoms colliding with rare gas atoms, N<inf>2</inf>, O<inf>2</inf>, and N<inf>2</inf>O molecules has been investigated by measuring Doppler broadened H atom spectra. The fast hydrogen atoms were generated by photodissociation of H<inf>2</inf>S at 243.2 nm, and the H atom spectra were measured by two photon absorption laser induced Lyman-α fluorescence. The H atom spectra show an anisotropic velocity distribution with the anisotropy parameter, β= -1.0 ± 0.05, without any colliding gases. Degradation of the anisotropy of the angular distribution was measured as a function of pressure of the colliding gases, He, Ar, Kr, N<inf>2</inf>, O<inf>2</inf>, and N<inf>2</inf>O and the collision cross sections for velocity direction change were measured.