Ultraviolet Photodissociation of 2-Methylallyl Radical
Ultraviolet photodissociation dynamics of 2-methylallyl radical from the 3p Ryd-berg state were investigated in the wave-length region of 226-244 nm using the high-n Rydberg atom time-of-flight(HRTOF)technique.The 2-methylallyl radicals were generated by 193 nm pho-tolysis of 3-chloro-2-methyl-1-propene precursors.The photofragment yield spectrum of H-atom products increases in intensity with decreasing wave-lengths in 226-244 nm.The TOF spec-tra of H-atom products show a bimodal structure.The predominant product channel(with～98％branching ratio)has a kinetic energy release peaking at～7 kcal/mol,with an average ratio of E/T in the total available energy,<fT>,of～0.18 in 226-244 nm and an isotropic product angular distribution.At the low Er,isotropic component is from statistical unimolecular decomposition of highly vibrationally excited hot 2-methylallyl to the methylenecyclopropane+H products,following internal conversion from the excited electron-ic state.The minor product channel(with～2％branching ratio)has a large kinetic energy peaking at～50 kcal/mol,with<fT>≈0.63 and an anisotropic angular distribution(β≈-0.2).At the high E/T,anisotropic component is non-statistical and is postulated to be from direct loss of H atom via the 3p Rydberg state or repulsive part of the ground state to the 1,3-butadi-ene+H products.
UltravioletPhotodissociationMethylallylRadical
Lucas Michael、覃院、陈旻、孙格、张劲松
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夏威夷大学马诺阿分校化学系,檀香山HI 96822
美国加州大学河滨分校化学系,河滨市92521
中国科学技术大学化学与材料科学学院化学物理系,合肥 230026
中国科学院大连化学物理研究所,大连 116023
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紫外光解离 甲基烯丙基 自由基
US National Science FoundationUC Riverside Dissertation-Year FellowshipChina Scholarships Council Fellowship
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