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In this work, we have extended our previous high resolution study of the vacuum ultraviolet emission spectrum of the D2 molecule [M. Roudjane, et al. J. Chem. Phys. 125, 214305 (2006)] up to 124.2 nm in order to investigate the B′ 1Σu+→X 1Σg+ band system. The analysis of the spectrum has been carried out by means of a complex spectrum visual identification code IDEN [V. I. Azarov, Phys. Scr. 44, 528 (1991); 48, 656, (1993)] and supported by theoretical calculations using ab initio data [L. Wolniewicz, J. Chem. Phys. 103, 1792 (1995); 99, 1851 (1993); G. Staszewska and L. Wolniewicz, J. Mol. Spectrosc. 212, 208 (2002); L. Wolniewicz and G. Staszewska, 220, 45 (2003)] which provided level energies and transition probabilities. More than 1480 new emission lines have been observed and 109 bands belonging to the B′ 1Σu+→X 1Σg+ system have been identified between 84.1 and 121.6 nm. Except for the υ′-0 bands that were reported in absorption [I. Dabrowski and G. Herzberg, Can. J. Phys. 52, 1110 (1974)], all the υ′-υ″ bands are reported here for the first time. The analysis led to the determination of 111 rovibronic energy levels in the B′ 1Σu+ state, of which 31 with higher rotational numbers J are new. Observed perturbations are accounted for through a set of coupled equations involving the four excited electronic states B 1Σu+, B′ 1Σu+, C 1Πu, and D 1Πu and including nonadiabatic couplings. The solution of this set provides the percent contribution of these four states to each of the observed rovibronic level. [ABSTRACT FROM AUTHOR]

The emission spectrum of the D2 molecule has been studied at high resolution in the vacuum ultraviolet region 78.5–102.7 nm. A detailed analysis of the two D 1Πu→X 1Σg+ and D′ 1Πu-→X 1Σg+ electronic band systems is reported. New and improved values of the level energies of the two upper states have been derived with the help of the program IDEN [V. I. Azarov, Phys. Scr. 44, 528 (1991); 48, 656 (1993)], originally developed for atomic spectral analysis. A detailed comparison is made between the observed energy levels and solutions of coupled equations using the newest ab initio potentials by Wolniewicz and co-workers [J. Chem. Phys. 103, 1792 (1995); 99, 1851 (1993); J. Mol. Spectros. 212, 208 (2002); 220, 45 (2003)] taking into account the nonadiabatic coupling terms for the D 1Πu state with the lowest electronic states B 1Σu+, C 1Πu, and B′ 1Σu+. A satisfactory agreement has been found for most of the level energies belonging to the D and D′ states. The remaining differences between observation and theory are probably due to nonadiabatic couplings with other higher electronic states which were neglected in the calculations. [ABSTRACT FROM AUTHOR]