Spectroscopic studies of the charge-transfer reaction He+ + Hg → He + (Hg+) * at thermal energy

The reaction He+ + Hg → He + (Hg+) * has been studied at thermal energy in a drift-tube--mass-spectrometer apparatus fitted with a sapphire window for observing the light emitted from the electronically excited ions. Over the wavelength range 300--900 nm, the only emissions observed from the (Hg+) * product ions are the 614.9-nm (7p 2P3/2 → 7s 2S1/2) and 794.4-nm (7p 2P1/2 → 7s 2S1/2) transitions, in approximately equal amounts. This equal branching in the case of reaction paths having substantially different energy defects, Δepsilon (infinity) = 0.27 and 0.72 eV, respectively, is not explained by present theoretical models of the charge-transfer process