The study of the D(') (1)Pi(u) state of H(2): transition probabilities from the ground state, predissociation yields, and natural linewidths

The absorption spectrum of the H(2) molecule was studied at high resolution in the 81-72 nm spectral range. A detailed analysis of the D(') (1)Pi(u)-->X (1)Sigma(g) (+) electronic band system is reported. In the spectrum, more than 70 new lines were assigned. For wavelengths longer than 75 nm, the D(') (1)Pi(u) (+) and (1)Pi(u) (-) components show a clearly different behavior: Tauhe (1)Pi(u) (+) one dissociates into H(1s)+H(n=2) whereas the (1)Pi(u) (-) one leads to molecular fluorescence. For shorter wavelengths, both components are predissociated into H(1s)+H(n=3). The predissociation yields, the dissociation widths, and the absolute values of the transition probabilities were measured over the vibrational progression from v(')=3 to 17, i.e., up to the dissociation limit. The comparison between these absolute transition probabilities and the values calculated in the adiabatic and nonadiabatic approximations demonstrates clearly the importance of nonadiabatic couplings.

Study of the B″B¯Σu+1 state of H2: Transition probabilities from the ground state, dissociative widths, and Fano parameters

The transition probabilities, the dissociation widths, and the associated Fano parameters for rovibronic lines with J"=0,...,3 of the absorption bands of the B"B 1Sigmau+ state out of the X 1Sigmag+ v"=0 ground state were measured over the complete vibrational progression, showing clearly that only the inner-well state with B" 4psigma character can absorb vuv light and predissociate efficiently. The absolute values of these transition probablities, predissociation widths, and Fano parameters were found to agree well with ab initio calculations if one takes into account that the calculations neglect nonadiabatic couplings.