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MO: Fachverband Molekülphysik
MO 6: Photochemie II
MO 6.7: Talk
Tuesday, March 11, 2008, 12:30–12:45, 3F
Inducing chemical reactions in doped quantum solids with vibrons — •David Anderson1, Falk Königsmann2, Nina Owschimikow2, and Nikolaus Schwentner2 — 1Department of Chemistry, University of Wyoming, Laramie, WY 82071, USA — 2Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, D-14195 Berlin
Solid parahydrogen quantum crystals doped with reactive species are potentially well suited for quantum control experiments. At liquid helium temperatures the entire solute-solvent condensed phase system resides in a nearly pure ground vibronic state and the internal vibrational coordinate of H2 can be exploited to selectively deliver energy to the reagents to trigger reaction. In situ 355 nm photodissociation of Cl2 and Br2 precursor molecules is an effective way to produce Cl and Br atom doped solid parahydrogen. Infrared-active vibrons (intramolecular H2 stretching modes) of Cl-atom doped solid parahydrogen have been shown [1] to trigger the reaction Cl+H2 → HCl+H. Systematic studies in solid H2, HD and D2 show widely varying reaction rates, a signature that the vibron induced mechanism involves H-atom tunneling. Currently we are investigating if ultrafast pulses can be utilized to excite coherent phonon motions [2] within solid parahydrogen with the aim of developing coherent control schemes for halogen molecules and atoms trapped in solid parahydrogen. [1] P. L. Raston and D. T. Anderson, Phys. Chem. Chem. Phys. 8, 3124 (2006). [2] M. Gühr, M. Bargheer, M. Fushitani, T. Kiljunen, and N. Schwentner, Phys. Chem. Chem. Phys. 9, 779 (2007).