Photo-induced intra-complex reactions in Mg+-2,2,2-trifluoroethanol

We induced the intra-complex reactions in Mg+-2,2,2-trifluoroethanol by photons in the spectral region of 240-410 nm. We observed the nonreactive channel product Mg+ and a number of reactive channel products throughout the whole excitation region. The reactive photoproducts originate from the scission of the C-O or C-F bond, as well as from the simultaneous rupture of both bonds. The action spectrum consists of two broad peaks between the atomic transition of Mg+(3 P-2<--3 S-2). Ab initio calculations show a minimum-energy structure, in which Mg+ attaches to the O atom and one of the three F atoms of 2,2,2-trifluoroethanol, forming a five-membered ring. The calculated absorption spectrum corresponding to the minimum-energy structure agrees nicely with the experimental action spectrum. The branching fractions of the photoproducts are approximately constant in a given spectral range, but they change significantly across the spectral ranges. The constant branching fractions point to the ground state reactions following traversals from the initially accessed excited states through conical intersections. On the other hand, the observation of the electronic state-specific branching fractions is explained by the orbital alignments of the excited electron, which is dictated by the five-membered ring structure of the complex. (C) 2002 American Institute of Physics