Stuttgart 2012 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 21: Poster 3: Cluster, Collisions, Energy Transfer, Photochemistry, Spectroscopy in He-Droplets

MO 21.19: Poster

Donnerstag, 15. März 2012, 16:30–19:00, Poster.IV

3D velocity mapping of the Hydrogen atom formation from the 193 nm photodissociation of borazine via (2+1)-REMPI — •Maik Veckenstedt, Mikhail Poretskiy, Christof Maul, and Karl Heinz Gericke — Institut for Physical and Theoretical Chemistry, University Braunschweig, Germany

The kinetic energy release and the spatial distribution of the Hydrogen atom formation from the 193nm photodissociation of borazine, B3N3H6, was studied by 3D velocity map imaging (VMI) setup. The excitation of borazine with 193nm and the following dissociation yields mainly in the production of the B3N3H5 and H atoms. In a two-laser experiment borazine was first excited with 193nm and the generated Hydrogen atoms were ionized through a (2+1)-REMPI process at 243nm. The 3D velocity vector of individual H atom fragments was detected with a time and position sensitive delay line detector. With this technique we received the Time-of-Flight mass spectrum and the spatial distribution for this H atoms formation.

The speed distribution of the H atoms is very board and because of the relative small energetic difference between the N-H (3,94eV) and B-H (4,26eV) bonding, one cannot clearly distinguish between the contribution of these two bonds. Moreover we observed an isotropic distribution of the Hydrogen atoms and a long lifetime of the excited borazine molecule. The spatial distribution obtained by 3D VMI corroborates the previous notion of the 193nm photodissociation process. Thus the Hydrogen atom formation is not a direct photodissociation, but more likely a predissociation.