Predissociation of thecΠu3State ofH2

A flight-time-difference method was used to measure the energy distribution of H-H fragment pairs arising from dissociative charge-exchange collisions of ${\mathrm{H}}_2^{+}$ ions. The spectrum exhibits sharp peaks which coincide with the energies of vibrational levels of the $c{}_{}{}^3{}_{}{}^{}\Pi _{\mathrm{u}}^{}{}_{}{}^{}$ state of ${\mathrm{H}}_2$ above the dissociation limit of the ground state. Predissociation into the $b{}_{}{}^3{}_{}{}^{}\Sigma _{\mathrm{u}}^{}{}_{}{}^{}$ state is the main decay channel of the $c{}_{}{}^3{}_{}{}^{}\Pi _{\mathrm{u}}^{}{}_{}{}^{}$ state. The lifetime is estimated to be ≤ ${10}^{-8\mathrm{}}$ sec.