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Global Reaction Pathways in the Photodissociation of I 3 − Ions in Solution at 267 and 400 nm Studied by Picosecond X‐ray Liquidography
Author(s) -
Kim Kyung Hwan,
Ki Hosung,
Oang Key Young,
Nozawa Shunsuke,
Sato Tokushi,
Kim Joonghan,
Kim Tae Kyu,
Kim Jeongho,
Adachi Shinichi,
Ihee Hyotcherl
Publication year - 2013
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.201300713
Subject(s) - photoexcitation , dissociation (chemistry) , chemistry , photodissociation , picosecond , ion , photochemistry , molecule , excitation , reaction dynamics , chemical physics , analytical chemistry (journal) , excited state , atomic physics , laser , optics , chromatography , engineering , physics , electrical engineering , organic chemistry
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 I 3 − photolysis, which changes subtly depending on the excitation wavelength, is elucidated. Upon 400 nm photoexcitation, the I 3 − ion dissociates into I 2 − and I. By contrast, upon 267 nm photoexcitation, the I 3 − ion undergoes both two‐body dissociation (I 2 − +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 I 3 − 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.