DIRECT OBSERVATION OF THE vdW BENDING BAND OF THE OCO-HF CLUSTER IN THE MILLIMETER-WAVE REGION

Abstract

The rovibrational transitions in the low frequency bending (vdW) mode of the intermolecular hydrogen bond in the OCO-HF cluster have been observed by millimeter-wave and submillimeter-wave spectroscopy combined with pulsed supersonic jet expansion technique. In this study, we observed 30 line belonging to the $\nu^{\prime} = 1^{1} - 0^{0}$ band in the frequency region from 260 to 320 GHz, where $\nu^{\prime}$ denotes quanta of OCO-HF skeltal bend excitation with l units of vibrational angular momentum. The observed spectra were analyzed with a linear molecule Hamiltonian and the band origin is determined to be $272548.8016(49) MHz$. We also detected several lines of the P-branch transitions of the $\nu_{bend}^{\prime} = 2^{2} - 1^{1}$ hot band.