title: Acetylene-vinylidene isomerization in ultrashort intense laser fields studied by triple ion-coincidence momentum imaging.
abstract: The isomerization of acetylene via hydrogen migration in intense laser fields (8 x 10(14) W/cm2) has been investigated by coincidence momentum imaging of the three-body Coulomb explosion process, C2H2 (3+)-->H+ + C+ + CH+. When ultrashort (9 fs) laser pulses are used, the angle between the momenta of C+ and H+ fragments exhibits a sharp distribution peaked at a small angle ( approximately 20 degrees ), showing that the hydrogen atom remains near the original carbon site in the acetylene configuration. On the other hand, a significantly broad distribution extending to larger momentum angles ( approximately 120 degrees ) is observed when the pulse duration is increased to 35 fs, indicating that the ultrafast isomerization to vinylidene is induced in the longer laser pulse.
authors.affiliation: Institute for Molecular Science, National Institutes of Natural Sciences, Myodaiji, Okazaki, Aichi 444-8585, Japan. hishi@ims.ac.jp
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Hishikawa
authors.forename: Akitaka
authors.initials: A
authors.lastname: Matsuda
authors.forename: Eiji J
authors.initials: EJ
authors.lastname: Takahashi
authors.forename: Mizuho
authors.initials: M
authors.lastname: Fushitani