Formation of metastable atomic hydrogen in the 2sstate from symmetry-resolved doubly excited states of molecular hydrogen

Abstract

The cross sections for the formation of the metastable atomic hydrogen in the 2$s$ state in photoexcitation of H${}_{2}$ and D${}_{2}$ were measured as a function of the incident photon energy in the range of the doubly excited states with their symmetries of the electronic states, ${}^{1}{\ensuremath{\Sigma}}_{u}^{+}$ or ${}^{1}{\ensuremath{\Pi}}_{u}$, being resolved. It has turned out from the comparison with the cross-section curves for other dissociation processes and the theoretical calculation [J. D. Bozek et al., J. Phys. B 39, 4871 (2006)] that the ${Q}_{2}$${}^{1}{\ensuremath{\Pi}}_{u}$(1) doubly excited state of H${}_{2}$ dissociates into both H(2$s$) + H(2$p$) and H(2$p$) + H(2$p$). The dissociation dynamics of this state has been discussed in terms of the nonadiabatic transition during neutral dissociations.