title: 1B2(1Sigma(u)+) excited state decay dynamics in CS2.
abstract: The authors report time resolved photoelectron spectra of the (1)B(2)((1)Sigma(u) (+)) state of CS(2) at pump wavelengths in the region of 200 nm. In contrast to previous studies, the authors find that the predissociation dynamics is not well described by a single exponential decay. Biexponential modeling of the authors' data reveals a rapid decay pathway (tau<50 fs), in addition to a longer lived channel (tau approximately 350-650 fs) that displays a marked change in apparent lifetime when the polarization of the pump laser is rotated with respect to that of the probe. Since the initially populated (1)B(2)((1)Sigma(u) (+)) state may decay to form either S((1)D) or S((3)P) products (the latter produced via a spin-orbit induced crossing from a singlet to a triplet electronic surface), this lifetime observation may be rationalized in terms of changes in the relative ionization cross section of these singlet and triplet states of CS(2) as a function of laser polarization geometry. The experimentally observed lifetime of the longer lived channel is therefore a superposition of these two pathways, both of which decay on very similar time scales.
authors.affiliation: Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario KIA 0R6, Canada.
authors.forename: Dave
authors.initials: D
authors.lastname: Townsend
authors.forename: Helmut
authors.initials: H
authors.lastname: Satzger
authors.forename: Tine
authors.initials: T
authors.lastname: Ejdrup
authors.forename: Anthony M D
authors.initials: AM
authors.lastname: Lee
authors.forename: Henrik
authors.initials: H
authors.lastname: Stapelfeldt
authors.forename: Albert
authors.initials: A
authors.lastname: Stolow