Knowledge Bank

A fast-beam photoionization-photodissociation double-resonance technique has been employed to excite transitions from selected rovibrational levels of the metastabe $c3\Pi u-$ state to the rapidly predissociated $j3\Delta g$ state of $H2$. Vibrational levels $v\prime -7-14$ and $v-7-12$ were observed (with $N\prime -2$, and for $v\prime -12,N\prime -3,4$ as well). The derived term energies in both states are in good agreement with $theory.1,2$ Predissociation of the $j3\Delta g$ state arises from coriolis interaction with the vibrational continuum of the $f3\Pi g$ state. The photodissociation resonances are slightly asymmetric, and have widths that decrease with increasing $v\prime$ from 29 to $10cm-1$. Calculated predissociation widths show the same vibrational trend, but are consistently 30*** smaller. Five narrow $(1.7-4cm-1)$ photodissociation resonances were also observed. We attribute these to $Q(1)$ and $R(1)$ transitions to the $n-43\Pi g$ state.