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Sub-nanosecond secondary geminate recombination in mercury halides HgX2 (X = I, Br) investigated by time-resolved x-ray scattering

Denis Leshchev,D. Khakhulin,G. Newby,H. Ki,H. Ihee,M. Wulff

Published 2019 in Journal of Chemical Physics

ABSTRACT

In this work, we present a detailed investigation on the recombination dynamics of mercury halides HgX2 (X = I, Br) in acetonitrile solution after UV-induced photodissociation. The study is performed by combining time-resolved wide-angle x-ray scattering (TRWAXS) and optical transient absorption spectroscopy. Up to 68% of the UV (266 nm) photodissociated HgX and X radicals that escape the solvent cage surrounding parent HgX2 recombine within a nanosecond after photodissociation. In contrast to classical primary geminate recombination, occurring on much faster time scales, we interpret the sub-nanosecond recombination channel as secondary geminate recombination (SGR), also referred to as diffusion-limited geminate recombination. The family of triatomic mercury halides therefore represents an important class of molecules to study chemical mechanisms of solvent-dependent SGR by TRWAXS. The methodology described here allows for direct mapping of the time-dependent inter-radical distance distribution function, a critical parameter for the assessment of the SGR dynamics in solution phase and solvation in general.In this work, we present a detailed investigation on the recombination dynamics of mercury halides HgX2 (X = I, Br) in acetonitrile solution after UV-induced photodissociation. The study is performed by combining time-resolved wide-angle x-ray scattering (TRWAXS) and optical transient absorption spectroscopy. Up to 68% of the UV (266 nm) photodissociated HgX and X radicals that escape the solvent cage surrounding parent HgX2 recombine within a nanosecond after photodissociation. In contrast to classical primary geminate recombination, occurring on much faster time scales, we interpret the sub-nanosecond recombination channel as secondary geminate recombination (SGR), also referred to as diffusion-limited geminate recombination. The family of triatomic mercury halides therefore represents an important class of molecules to study chemical mechanisms of solvent-dependent SGR by TRWAXS. The methodology described here allows for direct mapping of the time-dependent inter-radical distance distribution function,...

PUBLICATION RECORD

  • Publication year

    2019

  • Venue

    Journal of Chemical Physics

  • Publication date

    2019-08-05

  • Fields of study

    Materials Science, Chemistry

  • Identifiers
    DOI 10.1063/1.5096422
  • External record

    Open on Semantic Scholar

  • Source metadata

    Semantic Scholar

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