1B2(1Σu+) excited state decay dynamics in CS2

David Townsend, Helmut Satzger, Tine Ejdrup, Anthony M D Lee, Henrik Stapelfeldt, Albert Stolow

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Abstract

The authors report time resolved photoelectron spectra of the B-1(2)((1)Sigma(+)(u)) state of CS2 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 similar to 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 B-1(2)((1)Sigma(+)(u)) state may decay to form either S(D-1) or S(P-3) 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 CS2 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. (c) 2006 American Institute of Physics.

Original languageEnglish
Article number234302
Number of pages10
JournalJournal of Chemical Physics
Volume125
Issue number23
DOIs
Publication statusPublished - 21 Dec 2006

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