Photodissoziation von Halogenwasserstoff- und orientierten Wasserstoff-Edelgas-Halogen-Molekülen in Clusterumgebungen

Abstract

The object of this experimental work is the photodissociation of molecules and the interaction of the products with the surrounding cage atoms. Rare gas clusters of known size distribution are generated and doped with the different hydrogen halide molecules HCl, HBr and HI. They are placed on the surface or in the interior of the cluster. These systems are chosen because of their easier theoretical handling in contrast to bulk matter and because of the possibility of direct comparison with calculations. The molecules are photodissociated in the UV region at 243 and 193 nm. The outgoing H atoms are ionised in a 2+1 REMPI scheme also at 243 nm and their kinetic energy is measured in a Wiley-McLaren time-of-flight mass spectrometer. The ratio between caged and unperturbed exiting H atoms strongly depends on the site, the special surface state, the cage material, and, for the embedded case, on the cluster size. As a second topic measurements are presented which demonstrate the generation of the molecules HXeI and HXeCl as species of the ionic bound hydrogen-rare gas-halogen (HRgX) complexes. They are generated in the photodissociation of HI and HCl molecules on Xe clusters. The detection is achieved by asymmetric time-of-flight distributions caused by H atoms resulting from the photodissociation of the formed HRgX molecules oriented in combined strong laser and weak electrostatic fields.