Photochemistry of HgBr 2 in methanol investigated using time-resolved X-ray liquidography

Sunhong Jun, Jae Hyuk Lee, Jeongho Kim, Joonghan Kim, Kyung Hwan Kim, Qingyu Kong, Tae Kyu Kim, Manuela Lo Russo, Michael Wulff, Hyotcherl Ihee

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

We investigate the photoinduced dissociation of HgBr 2 in methanol and the ensuring structural dynamics of the photo-products over a time span from 100 ps to 1 µs after photolysis at 267 nm by using time-resolved X-ray liquidography (TRXL). By making use of the atomic-level structural sensitivity of X-ray scattering and the superb 100 ps time resolution of X-ray pulses from a 3rd-generation synchrotron, the structural dynamics of a chemical reaction in solution can be directly monitored. The measured time-dependent X-ray solution scattering signals, analyzed using global-fitting based on DFT calculations and MD simulations, show that photoexcited HgBr 2 dissociates via both two-body (HgBr + Br) and three-body (Hg + Br + Br) dissociation pathways with a ∼2: 1 branching ratio. Following dissociation, the photoproducts recombine via three reactions involving Br species: (1) Hg + Br, (2) HgBr + Br, and (3) Br + Br. The associated rate constants and branching ratios are determined from the global-fitting analysis. Also, we examine the energy dissipation from reacting solute molecules and relaxation of excited molecules to solvent bath accompanying the temperature rise of 0.54 K. Compared to a previous TRXL study of the photodissociation of HgI 2 , the results of this work suggest that the photodissociation pathway of HgBr 2 is different from that of HgI 2 , which dissociates predominantly via two-body dissociation, at least to within the currently available time resolution of ∼100 ps. In addition, the error analysis of the fit parameters used in the global-fitting are discussed in detail with a comparison of various error estimation algorithms.

Original languageEnglish
Pages (from-to)11536-11547
Number of pages12
JournalPhysical Chemistry Chemical Physics
Volume12
Issue number37
DOIs
Publication statusPublished - 2010 Jan 1

Fingerprint

Photochemical reactions
photochemical reactions
Methanol
methyl alcohol
Photodissociation
X rays
Structural dynamics
dissociation
Error analysis
x rays
dynamic structural analysis
photodissociation
Molecules
Photolysis
X ray scattering
Synchrotrons
Discrete Fourier transforms
Chemical reactions
Rate constants
Energy dissipation

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Jun, Sunhong ; Lee, Jae Hyuk ; Kim, Jeongho ; Kim, Joonghan ; Kim, Kyung Hwan ; Kong, Qingyu ; Kim, Tae Kyu ; Lo Russo, Manuela ; Wulff, Michael ; Ihee, Hyotcherl. / Photochemistry of HgBr 2 in methanol investigated using time-resolved X-ray liquidography In: Physical Chemistry Chemical Physics. 2010 ; Vol. 12, No. 37. pp. 11536-11547.
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abstract = "We investigate the photoinduced dissociation of HgBr 2 in methanol and the ensuring structural dynamics of the photo-products over a time span from 100 ps to 1 µs after photolysis at 267 nm by using time-resolved X-ray liquidography (TRXL). By making use of the atomic-level structural sensitivity of X-ray scattering and the superb 100 ps time resolution of X-ray pulses from a 3rd-generation synchrotron, the structural dynamics of a chemical reaction in solution can be directly monitored. The measured time-dependent X-ray solution scattering signals, analyzed using global-fitting based on DFT calculations and MD simulations, show that photoexcited HgBr 2 dissociates via both two-body (HgBr + Br) and three-body (Hg + Br + Br) dissociation pathways with a ∼2: 1 branching ratio. Following dissociation, the photoproducts recombine via three reactions involving Br species: (1) Hg + Br, (2) HgBr + Br, and (3) Br + Br. The associated rate constants and branching ratios are determined from the global-fitting analysis. Also, we examine the energy dissipation from reacting solute molecules and relaxation of excited molecules to solvent bath accompanying the temperature rise of 0.54 K. Compared to a previous TRXL study of the photodissociation of HgI 2 , the results of this work suggest that the photodissociation pathway of HgBr 2 is different from that of HgI 2 , which dissociates predominantly via two-body dissociation, at least to within the currently available time resolution of ∼100 ps. In addition, the error analysis of the fit parameters used in the global-fitting are discussed in detail with a comparison of various error estimation algorithms.",
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Jun, S, Lee, JH, Kim, J, Kim, J, Kim, KH, Kong, Q, Kim, TK, Lo Russo, M, Wulff, M & Ihee, H 2010, ' Photochemistry of HgBr 2 in methanol investigated using time-resolved X-ray liquidography ', Physical Chemistry Chemical Physics, vol. 12, no. 37, pp. 11536-11547. https://doi.org/10.1039/c002004d

Photochemistry of HgBr 2 in methanol investigated using time-resolved X-ray liquidography . / Jun, Sunhong; Lee, Jae Hyuk; Kim, Jeongho; Kim, Joonghan; Kim, Kyung Hwan; Kong, Qingyu; Kim, Tae Kyu; Lo Russo, Manuela; Wulff, Michael; Ihee, Hyotcherl.

In: Physical Chemistry Chemical Physics, Vol. 12, No. 37, 01.01.2010, p. 11536-11547.

Research output: Contribution to journalArticle

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AU - Jun, Sunhong

AU - Lee, Jae Hyuk

AU - Kim, Jeongho

AU - Kim, Joonghan

AU - Kim, Kyung Hwan

AU - Kong, Qingyu

AU - Kim, Tae Kyu

AU - Lo Russo, Manuela

AU - Wulff, Michael

AU - Ihee, Hyotcherl

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N2 - We investigate the photoinduced dissociation of HgBr 2 in methanol and the ensuring structural dynamics of the photo-products over a time span from 100 ps to 1 µs after photolysis at 267 nm by using time-resolved X-ray liquidography (TRXL). By making use of the atomic-level structural sensitivity of X-ray scattering and the superb 100 ps time resolution of X-ray pulses from a 3rd-generation synchrotron, the structural dynamics of a chemical reaction in solution can be directly monitored. The measured time-dependent X-ray solution scattering signals, analyzed using global-fitting based on DFT calculations and MD simulations, show that photoexcited HgBr 2 dissociates via both two-body (HgBr + Br) and three-body (Hg + Br + Br) dissociation pathways with a ∼2: 1 branching ratio. Following dissociation, the photoproducts recombine via three reactions involving Br species: (1) Hg + Br, (2) HgBr + Br, and (3) Br + Br. The associated rate constants and branching ratios are determined from the global-fitting analysis. Also, we examine the energy dissipation from reacting solute molecules and relaxation of excited molecules to solvent bath accompanying the temperature rise of 0.54 K. Compared to a previous TRXL study of the photodissociation of HgI 2 , the results of this work suggest that the photodissociation pathway of HgBr 2 is different from that of HgI 2 , which dissociates predominantly via two-body dissociation, at least to within the currently available time resolution of ∼100 ps. In addition, the error analysis of the fit parameters used in the global-fitting are discussed in detail with a comparison of various error estimation algorithms.

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