Translational energy distribution of excited deuterium atoms produced by controlled electron impact on D 2

Abstract

The Balmer-β line of the excited deuterium atom [D*( n = 4)] produced in e—D 2 collisions has been measured at high resolution (0.029–0.033 Å) and at various electron energies (17–100 eV). The translational energy distribution of D*( n = 4) has been calculated from analysis of its Doppler line shape. The distribution of D* has three major components as in the case of H*(n = 4) from H 2 reported in our previous paper. Their peaks lie at about 0, 6 and 8 eV. The excitation function of D* is found to have two thresholds at 17.4 and 26.4 eV. The second component of D* has a larger translational energy and a higher threshold than those of the corresponding component of H*. These results indicate that the contribution from the lowest doubly excited state, 1Σ g +(2pσ u) 2, is much smaller for D 2 than that for H 2.