Fig. 4: Energy level schemes of the H2O and H2S dimers.

(a) H2O dimer in the vibrational ground state, (b) H2S dimer in the ground and vibrationally excited state. The energy scheme in the ground state corresponds to our VRT levels calculated on a high-quality ab initio intermolecular potential. The arrows represent experimentally observed bands. The stars mark the enery levels populated at 0.37 K.