title: Photolysis of 1-C4H9I and 2-C4H9I at 266 nm: direct observation of the effect of branching on the photodissociation mechanism.
abstract: Photodissociation dynamics of 1-C(4)H(9)I and 2-C(4)H(9)I at 266 nm is investigated by velocity ion imaging. Photodissociation channels of 1-C(4)H(9)I and 2-C(4)H(9)I are analyzed and compared. For 1-C(4)H(9)I the photodissociation dynamics only correlates with direct dissociation via repulsive surfaces. While for 2-C(4)H(9)I, a new formation channel of I and I* atoms is observed. It is attributed to the repulsive mode along the C-I stretch, coupled with some bending motions. As the alkyl group becomes more branched, the contribution of bending modes to I and I* is much more obvious in the photodissociation of 2-C(4)H(9)I than in that of 1-C(4)H(9)I. Additionally, the curve-crossing probability between (3)Q(0) and (1)Q(1) increases greatly with branching, from 0.31 for 1-C(4)H(9)I to 0.70 for 2-C(4)H(9)I in the prompt dissociation channel; the relative quantum yield for I* decreases strongly with branching, from 0.65 for 1-C(4)H(9)I to 0.28 for 2-C(4)H(9)I.
authors.affiliation: State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, PR China.
authors.forename: Yuzhu
authors.initials: Y
authors.lastname: Liu
authors.forename: Qiusha
authors.initials: Q
authors.lastname: Zheng
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Rongrong
authors.initials: R
authors.lastname: Zhang
authors.forename: Yanmei
authors.initials: Y
authors.lastname: Wang
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang