The He2 - OCS complex: comparison between theory and experiment

OCS is an ideal probe for quantum solvation effects in cold helium clusters. He2-OCS is the "second step" in going from a single OCS molecule to a large doped superfluid helium cluster. Here assignment of the spectrum of He2-OCS is significantly extended to higher values of J, K, and vt (the low frequency torsional vibration). The observation of a new infrared band, OCS nu1 + nu3, taken together with the known nu1 band, enables assignments to be verified by comparing ground state combination differences. Relatively straightforward scaling of previously calculated theoretical energy levels gives a remarkably good fit to experiment