Cascade contribution to the H-2 Lyman band system from electron impact - art. no. 064702

The intensity of UV resonance transitions excited by electron impact is det ermined by both direct excitation and cascade processes. The lifetime for d ecay by spontaneous emission from a resonant state is short (typically < 10 ns). Using a pulsed electron gun technique established to separate these t wo effects we report a laboratory study of the UV spectrum of H-2 attribute d to cascade. We utilize the longer lifetimes (> 30 ns) for cascade channel s to measure the intense spectrum of the Lyman band system (B (1)Sigma(u)()-X (1)Sigma(g)(+)) of H-2 populated by cascade from higher lying (EF,GK,H( 1)Sigma(g)(+)) states.