Search for oriented HXeX molecules from the photolysis of HCl and HBr in xenon clusters

The orientation of free HRgX molecules arising from photodissociation of hydrogen halide molecules HX on rare gas clusters Rgn is investigated in a new experimental arrangement: the rare gas cluster beam with HX molecules in the surface is intersected by two focussed laser beams at one point, where it additionally interacts with a weak electrostatic field. The possibility to generate and successively orient this new class of molecules is analyzed for a couple of new candidate molecules. We observe oriented HXeCl molecules, while HXeBr and HKrCl escaped our detection scheme, as was expected from the analysis. Details of the measured kinetic energy distributions (KED) of H-fragment atoms from the HXeCl photodissociation are analyzed in terms of the Xe-H vibrational structure on the calculated potential energy surface of HXeCl. Finally, a strong indication for observation of HXeH molecules is found in the fragment KED peak around 0.35 eV. These symmetric molecules arise from the dissociation of more than one HX molecule on the cluster and are consistently observed for all HX-Xen systems with X=Cl,Br,I