Absorption Spectra of H2 in the Vacuum Ultraviolet Region. II. The B′—X, B″—X, D—X, and D′—X Bands

The absorption spectrum of the H₂ molecule has been studied in the wavelength region 840 to 930 Å with a 6.8 m grazing incidence vacuum spectrograph in combination with the helium continuum. All the possible levels, which lie below the dissociation limit $\mathrm{H}{\text{(1}}^2{S}_g\mathrm{)+}\mathrm{H}{\text{(2}}^2{S}_g{\text{,2}}^2{P}_u)$ , of the odd singlet states have been identified in the present investigation. There are strong heterogeneous perturbations between the B′ and the D states, weak heterogeneous perturbations between the B′ and D′ states and a medium strength homogeneous perturbation between the B′ and the B″ states. The perturbation parameters have been estimated in each case. In the present paper, the results of the rotational and vibrational analyses are given for the B′—X, B″—X, D—X, and D′—X bands. The experimental evidence found in the present study suggests that the predissociation in the levels with v≥3 of the D state is of the type b⁰, according to Mulliken's classification.