Hannover 2013 – wissenschaftliches Programm

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MO: Fachverband Molekülphysik

MO 27: Poster 3: Collisions, Electronic Spectroscopy, Energy Transfer, Quantum Chemistry, Molecular Dynamics, Photochemistry, Spectroscopy in He-Droplets

MO 27.23: Poster

Donnerstag, 21. März 2013, 16:00–18:30, Empore Lichthof

Photoion pair production in HCl — •Michael Schiller¹, Jingming Long², Christof Maul¹, and Karl-Heinz Gericke¹ — ¹Institut für Physikalische und Theoretische Chemie, TU Braunschweig, Hans-Sommer-Str. 10, 38106 Braunschweig, Germany — ²Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavik, Iceland

Hydrogen halides exhibit a complex fragmentation and ionization behavior upon resonant two-photon excitation of their Rydberg electronic states. E.g., three pathways are known to compete in the generation of H⁺ ions at an excitation energy of ca. 10 eV for HCl: 1) the dissociation of the molecular ion HCl⁺, 2) the ionization of electronically excited H* dissociation products, and 3) the photoion pair production yielding H⁺ + Cl⁻. When detecting H⁺ cations, e.g. by REMPI/TOF or Velocity Mapping techniques contributions from all channels interfere with each other, and only in favorable cases it is possible to tell them apart by spatial or kinetic energy distributions.

As channel 3 is unique in producing Cl⁻ anions as a primary photoproduct, we have set up an anion TOF spectrometer in order to monitor the photoion pair channel separately. Preliminary results will be presented, taking into account the hitherto neglected photoelectron dissociative attachment to electronically excited HCl. Special emphasis is laid on the role of the peculiar B¹Σ⁺ Rydberg state which holds a double minimum potential due to the mixing of the V¹Σ⁺ and E¹Σ⁺ states.