Photodissociation of hydrogen halide molecules in different cluster environments

The photodissociation of molecules and the interaction of the products with the surrounding cage atoms is an important field of research in solvation dynamics. The targeted generation of clusters with known size distributions and the placement of molecules on the surface or in the interior of these clusters allows us to carry out such investigations for finite systems as function of the size. We will present results of the photodissociation of HBr and HI molecules at 243 nm interacting with different rare gas clusters Ne-n, Ar-n, Kr-n, and Xe-n in the size range from n = 50 to 830. We mainly measure the kinetic energy of the outgoing H atoms in a time-of-flight mass spectrometer. The amount of fast, unperturbed or slow, caged and recombined H atoms depends strongly on the site, the special surface state, the cage material, the cluster size, and the kinetic energy available. The results are compared with calculations using mixed quantum-classical methods. In the photodissociation of HI in Xe-n clusters we observed the formation of HXeI that belongs to a recently discovered class of ionically bound systems. It is detected by the orientation in combined strong laser and weak electric fields. In small complexes (HBr), that were deposited in and on large rare gas clusters either vibrations or rotations were exited depending on their site and size.