Unusual mechanism for H3(+) formation from ethane as obtained by femtosecond laser pulse ionization and quantum chemical calculations

• Published in: The Journal of chemical physics Vol. 134; no. 11; p. 114302
• Main Authors: Kraus, Peter M, Schwarzer, Martin C, Schirmel, Nora, Urbasch, Gunter, Frenking, Gernot, Weitzel, Karl-Michael
• Format: Journal Article
• Language: English
• Published: United States 21.03.2011
• ISSN: 1089-7690
• DOI: 10.1063/1.3561311

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.