title: Ultrafast Relaxation Dynamics of the Ethylene Cation C(2)H(4)+.
abstract: We present a combined experimental and computational study of the relaxation dynamics of the ethylene cation. In the experiment, we apply an extreme-ultraviolet-pump/infrared-probe scheme that permits us to resolve time scales on the order of 10 fs. The photoionization of ethylene followed by an infrared (IR) probe pulse leads to a rich structure in the fragment ion yields reflecting the fast response of the molecule and its nuclei. The temporal resolution of our setup enables us to pinpoint an upper bound of the previously defined ethylene-ethylidene isomerization time to 30 ± 3 fs. Time-dependent density functional based trajectory surface hopping simulations show that internal relaxation between the first excited states and the ground state occurs via three different conical intersections. This relaxation unfolds on femtosecond time scales and can be probed by ultrashort IR pulses. Through this probe mechanism, we demonstrate a route to optical control of the important dissociation pathways leading to separation of H or H2.
authors.affiliation: Department of Physics, ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: André
authors.initials: A
authors.lastname: Ludwig
authors.affiliation: Laboratory of Computational Chemistry and Biochemistry, EPFL , 1015 Lausanne, Switzerland.
authors.forename: Elisa
authors.initials: E
authors.lastname: Liberatore
authors.affiliation: Department of Physics, ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: Jens
authors.initials: J
authors.lastname: Herrmann
authors.affiliation: Department of Physics, ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: Lamia
authors.initials: L
authors.lastname: Kasmi
authors.affiliation: Laboratory of Computational Chemistry and Biochemistry, EPFL , 1015 Lausanne, Switzerland.
authors.forename: Pablo
authors.initials: P
authors.lastname: López-Tarifa
authors.affiliation: Department of Physics, ETH Zurich , 8093 Zurich, Switzerland.|Institute of Applied Physics, University of Bern , 3012 Bern, Switzerland.
authors.forename: Lukas
authors.initials: L
authors.lastname: Gallmann
authors.affiliation: Laboratory of Computational Chemistry and Biochemistry, EPFL , 1015 Lausanne, Switzerland.
authors.forename: Ursula
authors.initials: U
authors.lastname: Rothlisberger
authors.affiliation: Department of Physics, ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: Ursula
authors.initials: U
authors.lastname: Keller
authors.affiliation: Department of Physics, ETH Zurich , 8093 Zurich, Switzerland.
authors.forename: Matteo
authors.initials: M
authors.lastname: Lucchini