High orbital angular momentum states in H2 and D2

Abstract

A characteristic group of lines observed in the infrared emission spectrum of H2 has been identified as representing the transitions between the 5g and the 4f group of levels. Because of nearly complete uncoupling of l from the molecular axis the appearance of this group of lines is very different from a normal band spectrum. An analysis was possible on the basis of ab initio computations of the spectrum using the knowledge of the vibrational levels, quadrupole moment, and the polarizability of the H+2 core. The validity of the assignments was further corroborated by agreement of the predicted spectra of D2 with the observed spectra. In addition, similar transitions corresponding to 4f–3d have been observed.