The Triplet3pComplex of the Hydrogen Molecule

Many peculiarities first observed in the Fulcher bands of the hydrogen molecule can be explained by the interaction of the $3p{}_{}{}^3{}_{}{}^{}\Pi$ with the $3p{}_{}{}^3{}_{}{}^{}\Sigma$ level. Such peculiarities are: irregular $\Lambda$-doublings, perturbations in the $3p{}_{}{}^3{}_{}{}^{}\Pi$ and $3p{}_{}{}^3{}_{}{}^{}\Sigma$ state, and the absence of $P$ and $R$ branches for large values of the vibrational quantum numbers. This last phenomenon is due to the pre-dissociation of the $3p{}_{}{}^3{}_{}{}^{}\Pi$ state.