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MARKKU RASANEN, MIKA PETTERSSON, JAN LUNDELL AND LEONID KHRIACHTCHEV, Laboratory of Physical Chemistry, P.O.Box 55 (A.I.Virtasen aukio 1), FIN-00014 University of Helsinki, FINLAND.
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UV-Photolysis of rare gas matrices doped with hydrogen halides yield H and Y (Y=halogen) atoms, and further excitation of the charge-transfer transition of XY pairs (X=Ar, Kr, Xe) results in mobilised holes. Permanent trapping of the holes may occur for instance in centers of type (XHX)+. Annealing of the UV-irradiated H-containing matrices results in extremely strong IR-absorptions, which could by doping experiments be shown to belong to neutral species of type HXY. The novel rare-gas containing species found so far are HXeCl, HXeBr, HXeI, HKrCl and HXeH. All these species are strongly polar and their common structure is (HX)+Y-. In order to learn more about the potential surface, detailed spectroscopic studies are performed on HXeI. This species can be photodecomposed into \underlineneutral atoms by infrared irradiation in the 3 µm region, and recovered quantitatively thermally at temperatures below 30 K. An Arrhenius analysis propose for the barrier from neutral atoms to HXeI a value of 700 cm-1. We suggest that this barrier originates from an avoided crossing between two singlet surfaces limiting either to separated atoms H + Xe + I or to ionic species (HXe)+ + I-.
References: \newline \beginlist \usecountermatr em Neutral rare-gas containing charge-transfer molecules in solid matrices. I. HXeCl, HXeBr, HXeI and HKrCl in Kr and Xe. M.Pettersson, J.Lundell, M.Räsänen, J.Chem.Phys. 102 (1995) 6423-31. em Neutral rare gas containing charge-transfer molecules in solid matrices. II. HXeH, HXeD and DXeD in Xe. M.Pettersson, J.Lundell, M.Räsänen, J.Chem.Phys. 103 (1995) 205-10. em The mechanism of formation and IR-induced decomposition of HXeI in solid Xe. M.Pettersson, J.Nieminen, L.Khriachtchev, M.Räsänen, J.Chem.Phys. to be submitted. \endlist