title: Unusual mechanism for H3(+) formation from ethane as obtained by femtosecond laser pulse ionization and quantum chemical calculations.
abstract: The formation of H(3)(+) 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 H(3)(+) formation at the molecular level. The experimental approach involves femtosecond laser pulse ionization of ethane leading to H(3)(+) 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 H(2) molecule attached to a C(2)H(4)(2+) entity but IRC calculations show that it belongs to the reaction channel yielding C(2)H(3)(+) + H(3)(+). Experimentally measured kinetic energies of the correlated H(3)(+) and C(2)H(3)(+) ions confirm the reaction path suggested by theory.
authors.affiliation: Fachbereich Chemie, Physikalische Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße, D-35032 Marburg, Germany.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Kraus
authors.forename: Martin C
authors.initials: MC
authors.lastname: Schwarzer
authors.forename: Nora
authors.initials: N
authors.lastname: Schirmel
authors.forename: Gunter
authors.initials: G
authors.lastname: Urbasch
authors.forename: Gernot
authors.initials: G
authors.lastname: Frenking
authors.forename: Karl-Michael
authors.initials: KM
authors.lastname: Weitzel