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Global Reaction Pathways in the Photodissociation of I3 Ions in Solution at 267 and 400 nm Studied by Picosecond X-ray Liquidography

Authors

  • Dr. Kyung Hwan Kim,

    1. Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 305-701 (Republic of Korea), Fax: (+82) 42-350-2810
    2. Department of Chemistry, KAIST, Daejeon 305-701 (Republic of Korea)
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  • Hosung Ki,

    1. Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 305-701 (Republic of Korea), Fax: (+82) 42-350-2810
    2. Department of Chemistry, KAIST, Daejeon 305-701 (Republic of Korea)
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  • Key Young Oang,

    1. Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 305-701 (Republic of Korea), Fax: (+82) 42-350-2810
    2. Department of Chemistry, KAIST, Daejeon 305-701 (Republic of Korea)
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  • Prof. Shunsuke Nozawa,

    1. Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
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  • Dr. Tokushi Sato,

    1. Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
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  • Prof. Joonghan Kim,

    1. Department of Chemistry, The Catholic University of Korea, Bucheon 420-743 (Republic of Korea)
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  • Prof. Tae Kyu Kim,

    1. Department of Chemistry and Chemistry Institute of Functional Materials, Pusan National University, Busan 609-735 (Republic of Korea)
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  • Prof. Jeongho Kim,

    1. Department of Chemistry, Inha University, Incheon 402-751 (Republic of Korea)
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  • Prof. Shin-ichi Adachi,

    1. Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
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  • Prof. Hyotcherl Ihee

    Corresponding author
    1. Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 305-701 (Republic of Korea), Fax: (+82) 42-350-2810
    2. Department of Chemistry, KAIST, Daejeon 305-701 (Republic of Korea)
    • Center for Nanomaterials and Chemical Reactions, Institute for Basic Science, Daejeon 305-701 (Republic of Korea), Fax: (+82) 42-350-2810

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Abstract

The mechanism of a photochemical reaction involves the formation and dissociation of various short-lived species on ultrafast timescales and therefore its characterization requires detailed structural information on the transient species. By making use of a structurally sensitive X-ray probe, time-resolved X-ray liquidography (TRXL) can directly elucidate the structures of reacting molecules in the solution phase and thus determine the comprehensive reaction mechanism with high accuracy. In this work, by performing TRXL measurements at two different wavelengths (400 and 267 nm), the reaction mechanism of I3 photolysis, which changes subtly depending on the excitation wavelength, is elucidated. Upon 400 nm photoexcitation, the I3 ion dissociates into I2 and I. By contrast, upon 267 nm photoexcitation, the I3 ion undergoes both two-body dissociation (I2+I) and three-body dissociation (I+2I) with 7:3 molar ratio. At both excitation wavelengths, all the transient species ultimately disappear in 80 ns by recombining to form the I3 ion nongeminately. In addition to the reaction dynamics of solute species, the results reveal the transient structure of the solute/solvent cage and the changes in solvent density and temperature as a function of time.

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