skip to main content

DOE PAGESDOE PAGES

Title: Molecular modeling and assignment of IR spectra of the hydrated excess proton in isotopically dilute water

Infrared (IR) spectroscopy of the water O–H stretch has been widely used to probe both the local hydrogen-bonding structure and dynamics of aqueous systems. Although of significant interest, the IR spectroscopy of excess protons in water remains difficult to assign as a result of extensive and strong intermolecular interactions in hydrated proton complexes. As an alternate approach, we develop a mixed quantum-classical model for the vibrational spectroscopy of the excess proton in isotopically dilute water that draws on frozen proton-water clusters taken from reactive molecular dynamics trajectories of the latest generation multi-state empirical valence bond proton model (MS-EVB 3.2). A semi-empirical single oscillator spectroscopic map for the instantaneous transition frequency and transition dipole moment is constructed using potential energy surfaces for the O–H stretch coordinate of the excess proton using electronic structure calculations. Calculated spectra are compared with experimental spectra of dilute H + in D 2O obtained from double-difference FTIR to demonstrate the validity of the map. The model is also used to decompose IR spectra into contributions from different aqueous proton configurations. We find that the O–H transition frequency continuously decreases as the oxygen-oxygen length for a special pair proton decreases, shifting from Eigen- to Zundel-like configurations. Inmore » conclusion, the same shift is accompanied by a shift of the flanking water stretches of the Zundel complex to higher frequency than the hydronium O–H vibrations.« less
Authors:
 [1] ; ORCiD logo [1] ;  [1] ;  [1]
  1. Univ. of Chicago, IL (United States). Dept. of Chemistry, James Franck Inst., and Inst. for Biophysical Dynamics
Publication Date:
Grant/Contract Number:
SC0005418; ACI-1053575; SC0014305
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 145; Journal Issue: 15; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Department of Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois 60637, USA
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
OSTI Identifier:
1465106
Alternate Identifier(s):
OSTI ID: 1329330

Biswas, Rajib, Carpenter, William, Voth, Gregory A., and Tokmakoff, Andrei. Molecular modeling and assignment of IR spectra of the hydrated excess proton in isotopically dilute water. United States: N. p., Web. doi:10.1063/1.4964723.
Biswas, Rajib, Carpenter, William, Voth, Gregory A., & Tokmakoff, Andrei. Molecular modeling and assignment of IR spectra of the hydrated excess proton in isotopically dilute water. United States. doi:10.1063/1.4964723.
Biswas, Rajib, Carpenter, William, Voth, Gregory A., and Tokmakoff, Andrei. 2016. "Molecular modeling and assignment of IR spectra of the hydrated excess proton in isotopically dilute water". United States. doi:10.1063/1.4964723. https://www.osti.gov/servlets/purl/1465106.
@article{osti_1465106,
title = {Molecular modeling and assignment of IR spectra of the hydrated excess proton in isotopically dilute water},
author = {Biswas, Rajib and Carpenter, William and Voth, Gregory A. and Tokmakoff, Andrei},
abstractNote = {Infrared (IR) spectroscopy of the water O–H stretch has been widely used to probe both the local hydrogen-bonding structure and dynamics of aqueous systems. Although of significant interest, the IR spectroscopy of excess protons in water remains difficult to assign as a result of extensive and strong intermolecular interactions in hydrated proton complexes. As an alternate approach, we develop a mixed quantum-classical model for the vibrational spectroscopy of the excess proton in isotopically dilute water that draws on frozen proton-water clusters taken from reactive molecular dynamics trajectories of the latest generation multi-state empirical valence bond proton model (MS-EVB 3.2). A semi-empirical single oscillator spectroscopic map for the instantaneous transition frequency and transition dipole moment is constructed using potential energy surfaces for the O–H stretch coordinate of the excess proton using electronic structure calculations. Calculated spectra are compared with experimental spectra of dilute H+ in D2O obtained from double-difference FTIR to demonstrate the validity of the map. The model is also used to decompose IR spectra into contributions from different aqueous proton configurations. We find that the O–H transition frequency continuously decreases as the oxygen-oxygen length for a special pair proton decreases, shifting from Eigen- to Zundel-like configurations. In conclusion, the same shift is accompanied by a shift of the flanking water stretches of the Zundel complex to higher frequency than the hydronium O–H vibrations.},
doi = {10.1063/1.4964723},
journal = {Journal of Chemical Physics},
number = 15,
volume = 145,
place = {United States},
year = {2016},
month = {10}
}