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Title: Role of excited state solvent fluctuations on time-dependent fluorescence Stokes shift

Abstract

We explore the connection between the solvation dynamics of a chromophore upon photon excitation and equilibrium fluctuations of the solvent. Using molecular dynamics simulations, fluorescence Stokes shift for the tryptophan in Staphylococcus nuclease was examined using both nonequilibrium calculations and linear response theory. When the perturbed and unperturbed surfaces exhibit different solvent equilibrium fluctuations, the linear response approach on the former surface shows agreement with the nonequilibrium process. This agreement is excellent when the perturbed surface exhibits Gaussian statistics and qualitative in the case of an isomerization induced non-Gaussian statistics. However, the linear response theory on the unperturbed surface breaks down even in the presence of Gaussian fluctuations. Experiments also provide evidence of the connection between the excited state solvent fluctuations and the total fluorescence shift. These observations indicate that the equilibrium statistics on the excited state surface characterize the relaxation dynamics of the fluorescence Stokes shift. Our studies specifically analyze the Gaussian fluctuations of the solvent in the complex protein environment and further confirm the role of solvent fluctuations on the excited state surface. The results are consistent with previous investigations, found in the literature, of solutes dissolved in liquids.

Authors:
;  [1]
  1. Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)
Publication Date:
OSTI Identifier:
22493196
Resource Type:
Journal Article
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 143; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-9606
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; EQUILIBRIUM; EXCITATION; EXCITED STATES; FLUCTUATIONS; FLUORESCENCE; ISOMERIZATION; LIQUIDS; MOLECULAR DYNAMICS METHOD; PHOTONS; PROTEINS; SIMULATION; SOLUTES; SOLVATION; SOLVENTS; STAPHYLOCOCCUS; STATISTICS; SURFACES; TIME DEPENDENCE; TRYPTOPHAN

Citation Formats

Li, Tanping, and Kumar, Revati. Role of excited state solvent fluctuations on time-dependent fluorescence Stokes shift. United States: N. p., 2015. Web. doi:10.1063/1.4934661.
Li, Tanping, & Kumar, Revati. Role of excited state solvent fluctuations on time-dependent fluorescence Stokes shift. United States. https://doi.org/10.1063/1.4934661
Li, Tanping, and Kumar, Revati. 2015. "Role of excited state solvent fluctuations on time-dependent fluorescence Stokes shift". United States. https://doi.org/10.1063/1.4934661.
@article{osti_22493196,
title = {Role of excited state solvent fluctuations on time-dependent fluorescence Stokes shift},
author = {Li, Tanping and Kumar, Revati},
abstractNote = {We explore the connection between the solvation dynamics of a chromophore upon photon excitation and equilibrium fluctuations of the solvent. Using molecular dynamics simulations, fluorescence Stokes shift for the tryptophan in Staphylococcus nuclease was examined using both nonequilibrium calculations and linear response theory. When the perturbed and unperturbed surfaces exhibit different solvent equilibrium fluctuations, the linear response approach on the former surface shows agreement with the nonequilibrium process. This agreement is excellent when the perturbed surface exhibits Gaussian statistics and qualitative in the case of an isomerization induced non-Gaussian statistics. However, the linear response theory on the unperturbed surface breaks down even in the presence of Gaussian fluctuations. Experiments also provide evidence of the connection between the excited state solvent fluctuations and the total fluorescence shift. These observations indicate that the equilibrium statistics on the excited state surface characterize the relaxation dynamics of the fluorescence Stokes shift. Our studies specifically analyze the Gaussian fluctuations of the solvent in the complex protein environment and further confirm the role of solvent fluctuations on the excited state surface. The results are consistent with previous investigations, found in the literature, of solutes dissolved in liquids.},
doi = {10.1063/1.4934661},
url = {https://www.osti.gov/biblio/22493196}, journal = {Journal of Chemical Physics},
issn = {0021-9606},
number = 17,
volume = 143,
place = {United States},
year = {Sat Nov 07 00:00:00 EST 2015},
month = {Sat Nov 07 00:00:00 EST 2015}
}