The triplet 3s,3d complex of HD

Abstract
High-resolution laser photofragment spectroscopy of the 3s,3d←2p c 3Π−u transitions in HD has been performed in a fast mass and state-selected beam. Transition wave numbers and rotational energy levels are given for v=0–3 of the h3∑+g, g 3∑+g, i 3Πg, and j 3Δg states. The data are represented by an effective Hamiltonian which accounts for the rotational breakdown of the Born–Oppenheimer approximation (L-uncoupling). The model parameters indicate a vibrational Born–Oppenheimer breakdown in the i 3Πg state. Good agreement with the most accurate ab initio calculations is obtained.