Laser probing of the electron-impact excited c(2p) 3Πu manifold of states in H2

A stepwise laser excitation method has been used to probe individual ro-vibrational levels in the molecular hydrogen metastable c(2p) 3Πu manifold of states. Metastable states produced by electron-impact excitation are subsequently excited by the absorption of a single UV laser photon, producing a complex triplet nd Rydberg spectrum observed via field ionization and autoionization. The spectrum has been analysed to determine quantum numbers of the states associated with the transitions. Excitation functions for individual ro-vibrational states in the c(2p) 3Πu manifold are then determined as a function of electron-impact energy.