Vibrational spectroscopy and matrix-site geometries of HArF, HKrF, HXeCl, and HXeI in rare-gas solids

Abstract

The vibrational spectroscopy and the matrix-site geometries of several novel rare-gas compounds in the matrix environment were computed theoretically, and compared with experiment. Ab initio calculations are used in the fitting of analytical potential surfaces for the HRgY molecules and for the interactions between HRgY and the matrix atoms Rg. With these potentials, matrix-site geometries for the molecule in the solid are computed. Finally, the vibrational spectroscopy of HRgY in the Rg matrix is computed using the vibrational self-consistent field (VSCF) method. The VSCF includes anharmonic effects, that are essential in this case. The version of VSCF used here includes coupling between HRgY and the vibrations of the solid atoms. The vibrations of 72 matrix atoms are treated. The main results are: (1) The matrix shifts are considerably greater than typically found for neutral, strongly bond molecules, but are much smaller than discrepancies between theory and experiment. This can be attributed to the insufficient accuracy of the potentials used for the HRgY molecules. This calls for better future description of the electronic structure of HRgY. (2) The matrix shifts and splitting effects are interpreted by the calculations in terms of the site geometries involved. These effects are very different for HArF, HKrF than for HXeCl, HXeI. (3) The computed matrix-site splittings are in semiquantitative accord with experiment. This supports the interaction potentials used between HRgY and the matrix. The results provide insights on the effects of the matrix on the rare-gas molecules.

Interaction of rare-gas-containing molecules with nitrogen: Matrix-isolation and ab initio study of HArF⋯N2, HKrF⋯N2, and HKrCl⋯N2 complexes

“…15 The simulations suggest that the stable and unstable configurations correspond to HArF and HKrF molecules in single and double substitutional sites with different thermal stability. 7,20 In contrast, HKrCl seems to occupy only one matrix-site configuration, and no thermal relaxation for it is found experimentally. 16 -19 C. HArF¯N 2 After deposition of a HF/N 2 /Ar (1:4:2000) mixture at 20 K, the absorption band of HF¯N 2 complex at 3881.5 cm Ϫ1 dominates in the IR absorption spectra ͓see Fig.…”

Matrix effect on vibrational frequencies: Experiments and simulations for HCl and HNgCl (Ng = Kr and Xe)

“…The blue-shifting effect of the matrix on the H−Ng stretching mode was first found in the calculations of Runeberg et al for HArF@Ar 6 where a shift of +38 cm −1 of the H−Ar stretching mode was promoted by the interaction with the cluster. 16 Matrix effects on several HNgY molecules were studied by Bihary et al, 17 but the used interaction potentials were not of quantitative accuracy, and the results were not satisfactory. Among other attempts, we mention the matrix-site splitting of the H−Ar stretching mode of HArF in an Ar matrix successfully simulated by Bochenkova et al 18,19 Liu et al applied the polarizable continuum model to different Ng molecules to simulate matrix-solvation effects.…”

Formation of HArF in solid Ar revisited: Are mobile vacancies involved in the matrix-site conversion at 30 K?

“…A number of simulations appeared quickly after the experimental report. [5][6][7] Bihary et al assigned the stable absorptions to HArF in a compact ͑single-substitutional, SS͒ matrix site and the unstable absorptions to HArF in a loose ͑double-substitutional, DS͒ site. 5 Their assignment was based on comparison between the experimental and theoretical absorption frequencies.…”

“…[5][6][7] Bihary et al assigned the stable absorptions to HArF in a compact ͑single-substitutional, SS͒ matrix site and the unstable absorptions to HArF in a loose ͑double-substitutional, DS͒ site. 5 Their assignment was based on comparison between the experimental and theoretical absorption frequencies. In contrast, Jolkkonen et al have assigned the stable absorption bands to HArF in a loose site and the unstable absorptions to HArF in a compact site.…”