Evidence of Lyman transitions of high rovibrationally excited HD and D2 detected by laser induced fluorescence in the VUV

The vacuum-UV laser induced fluorescence spectrum of molecular neutral species present in an H2/D2 plasma expansion has been recorded from 60 500 cm−1 to 83 500 cm−1. It will be shown that this VUV spectrum results from X 1 Σ g + ↔ B 1 Σ u + (Lyman) transitions in H2, HD and D2 molecules that are high rovibrationally excited. This is inferred from the comparison of simulated Lyman spectra based on spectroscopic data for H2, HD and D2 with the measured VUV spectra.