Infrared spectroscopy of XeF 2, XeF 4 and XeF 6 molecules in liquid-xenon solution

Abstract

The infrared spectra of XeF 2, XeF 4 and XeF 6 molecules were investigated in liquefied noble gas solutions. It is shown that incryogenic solution (liquid Xe, T=180 K) XeF 2 and XeF 4 molecular structure weak distortion due to the effective solute-solvent interaction takes place. The anharmoniciti constants X 13 (XeF 2) and X 46 (XeF 4) were computed. It was found that the increase of XeF 6 concentration in a liquid xenon solution causes both the decreas of the number of monomers XeF 6 with the strong 596 cm −1 band and the polymers (XeF 6) n formation characterised by intensive band group in 620–640 cm −1 region. The equilibrium constants were computed for reaction n(XeF 6) = (XeF 6) n (n=2,4). It is shown that in contrast to classical octahedral molecules such as SF 6, UF 6 and others [1], polymerization of xenon hexafluoride is followed by the stabilization of non-rigid structure of this molecule at the expense of the mobiliti decrease of the fluorine atoms which results in the decrease of XeF bond rigidity. The results of the studies on IR spectra of XeF 6 in liquid-xenon solution over the wide frequency range 400–2000 cm −1 led to the conclusion that the geometrical configuration of an octahedron distorted to a C 3v-symmetry is the basic one for xenon hexafluoride.