Matrix isolated HF: the high-resolution infrared spectrum of a cryogenically solvated hindered rotor Original Research Article

The spectra of the infrared fundamentals of HF and DF isolated in solid Ar were recorded at high resolution, and general agreement with previous measurements was found. The temperature behavior of the spectra show that both species are nearly free rotors, in agreement with previous observations. The positions and splittings of these features, however, show that the rotation is at least slightly hindered and that more than one matrix site is observed. These spectra have been simulated using recent ArHF and Ar2 intermolecular potentials in a calculation of the rotational energy states of various matrix sites. The Hutson H6(4, 3, 2) potential gives reasonable to excellent agreement between the predicted and observed features, including the redshift from the gas phase to the matrix, and the spectra are interpreted in terms of two sites: a single substitution site, which perturbs the rotational spectrum slightly, and a distorted interstitial site which is more hindering.