Hydrogen bond energies of the HF and HCl dimers from absolute infrared intensities

Abstract

The dissociation energies of the hydrogen-bonded complexes, (HF)2 and (HCl)2, have been obtained from high-resolution measurements of absolute infrared line strengths at a single temperature and pressure under the assumption of minimally perturbed local-mode behavior of the outer hydrogen stretch. The zero-point dissociation energies for the HF and HCl dimers are D0=1038(+43, −34) and 431(±22) cm−1, respectively. Estimates of the zero-point energies of the low frequency intermolecular vibrations enable us to obtain the well depths and equilibrium dissociation energies for comparison to ab initio calculations and empirical models.