The observation of stimulated emission in the 119 to 149 nm range from HD excited by picosecond 193 nm radiation

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Abstract
Intense stimulated emission in the 119 to 149 nm region is observed from HD excited by two quanta at 193 nm. For certain transitions, the conversion efficiency approaches 1% so that peak powers of ∼10 MW are produced. Electron collisions with the HD (E,F) level are found to efficiently transfer population to the HD(C) state which produces stimulated emission on several C → X Werner band lines in the vicinity of 120 nm. The data on the pressure dependence of the stimulated signals strongly support the conclusion that, in comparison to H2, HD exhibits a large isotopic dependence on the cross section for rotationally inelastic electron collisions in electronically excited states. The rate constant for this rotationally inelastic process is estimated as ∼2×10−7 cm3/s. This is the first observation of an isotopically sensitive electron collisional process involving an electronically excited level.