Dresden 2011 – scientific programme
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MO: Fachverband Molekülphysik
MO 12: Femtosecond Spectroscopy III
MO 12.5: Talk
Wednesday, March 16, 2011, 11:30–11:45, TOE 317
Unusual mechanism for H3+ formation from ethane as obtained by femtosecond laser pulse ionization and quantum chemical calculations — Peter Kraus, Martin Schwarzer, •Nora Schirmel, Gunter Urbasch, Gernot Frenking, and Karl-Michael Weitzel — Fachbereich Chemie, Philipps-Universität Marburg, Deutschland
The formation of H3+ from saturated hydrocarbon molecules represents a prototype of a complex chemical process, involving the breaking and the making of chemical bonds. We present a combined theoretical and experimental investigation providing for the first time an understanding of the mechanism of H3+ formation at the molecular level.[1] The experimental approach involves femtosecond laser pulse ionization of ethane leading to H3+ ions with kinetic energies on the order of 4 to 6.5 eV. The theoretical approach involves high-level quantum chemical calculation of the complete reaction path. The calculations confirm that the process takes place on the potential energy surface of the ethane dication. A surprising result of the theoretical investigation is, that the transition state of the process can be formally regarded as a H2 molecule attached to a C2H42+ entity but IRC calculations show that it belongs to the reaction channel yielding C2H3+ + H3+. Experimentally measured kinetic energies of the correlated H3+ and C2H3+ ions confirm the reaction path suggested by theory. [1] Peter M. Kraus, Martin C. Schwarzer, Nora Schirmel, Gunter Urbasch, Gernot Frenking and Karl-Michael Weitzel, to be published.