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Title: Ultrafast photodissociation dynamics and nonadiabatic coupling between excited electronic states of methanol probed by time-resolved photoelectron spectroscopy

Abstract

The electronic and nuclear dynamics in methanol, following 156 nm photoexcitation, are investigated by combining a detailed analysis of time-resolved photoelectron spectroscopy experiments with electronic structure calculations. The photoexcitation pump pulse is followed by a delayed 260 nm photoionization probe pulse to produce photoelectrons that are analyzed by velocity map imaging. The yields of mass-resolved ions, measured with similar experimental conditions, are found to exhibit the same time-dependence as specific photoelectron spectral features. Energy-resolved signal onset and decay times are extracted from the measured photoelectron spectra to achieve high temporal resolution, beyond the 20 fs pump and probe pulse durations. When combined with ab initio calculations of selected cuts through the excited state potential energy surfaces, this information allows the dynamics of the transient excited molecule, which exhibits multiple nuclear and electronic degrees of freedom, to be tracked on its intrinsic few-femtosecond time scale. Within 15 fs of photoexcitation, we observe nuclear motion on the initially bound photoexcited 2 1A" (S 2) electronic state, through a conical intersection with the 1 1A' (S3) state, which reveals paths to photodissociation following C–O stretch and C–O–H angle opening.

Authors:
 [1];  [2]; ORCiD logo [3];  [4];  [1];  [5]; ORCiD logo [6];  [5]; ORCiD logo [5]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Davis, CA (United States); Kansas State Univ., Manhattan, KS (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  4. SLAC National Accelerator Lab., Menlo Park, CA (United States). Photon Ultrafast Laser Science and Engineering Inst. (PULSE)
  5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  6. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Davis, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division
OSTI Identifier:
1528785
Alternate Identifier(s):
OSTI ID: 1542954
Grant/Contract Number:  
AC02-76SF00515; W911NF-14-1-0383; AC02-05CH11231
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 150; Journal Issue: 11; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English

Citation Formats

Champenois, Elio G., Greenman, Loren, Shivaram, Niranjan, Cryan, James P., Larsen, Kirk A., Rescigno, Thomas N., McCurdy, C. William, Belkacem, Ali, and Slaughter, Daniel S. Ultrafast photodissociation dynamics and nonadiabatic coupling between excited electronic states of methanol probed by time-resolved photoelectron spectroscopy. United States: N. p., 2019. Web. doi:10.1063/1.5079549.
Champenois, Elio G., Greenman, Loren, Shivaram, Niranjan, Cryan, James P., Larsen, Kirk A., Rescigno, Thomas N., McCurdy, C. William, Belkacem, Ali, & Slaughter, Daniel S. Ultrafast photodissociation dynamics and nonadiabatic coupling between excited electronic states of methanol probed by time-resolved photoelectron spectroscopy. United States. doi:10.1063/1.5079549.
Champenois, Elio G., Greenman, Loren, Shivaram, Niranjan, Cryan, James P., Larsen, Kirk A., Rescigno, Thomas N., McCurdy, C. William, Belkacem, Ali, and Slaughter, Daniel S. Thu . "Ultrafast photodissociation dynamics and nonadiabatic coupling between excited electronic states of methanol probed by time-resolved photoelectron spectroscopy". United States. doi:10.1063/1.5079549.
@article{osti_1528785,
title = {Ultrafast photodissociation dynamics and nonadiabatic coupling between excited electronic states of methanol probed by time-resolved photoelectron spectroscopy},
author = {Champenois, Elio G. and Greenman, Loren and Shivaram, Niranjan and Cryan, James P. and Larsen, Kirk A. and Rescigno, Thomas N. and McCurdy, C. William and Belkacem, Ali and Slaughter, Daniel S.},
abstractNote = {The electronic and nuclear dynamics in methanol, following 156 nm photoexcitation, are investigated by combining a detailed analysis of time-resolved photoelectron spectroscopy experiments with electronic structure calculations. The photoexcitation pump pulse is followed by a delayed 260 nm photoionization probe pulse to produce photoelectrons that are analyzed by velocity map imaging. The yields of mass-resolved ions, measured with similar experimental conditions, are found to exhibit the same time-dependence as specific photoelectron spectral features. Energy-resolved signal onset and decay times are extracted from the measured photoelectron spectra to achieve high temporal resolution, beyond the 20 fs pump and probe pulse durations. When combined with ab initio calculations of selected cuts through the excited state potential energy surfaces, this information allows the dynamics of the transient excited molecule, which exhibits multiple nuclear and electronic degrees of freedom, to be tracked on its intrinsic few-femtosecond time scale. Within 15 fs of photoexcitation, we observe nuclear motion on the initially bound photoexcited 21A" (S2) electronic state, through a conical intersection with the 11A' (S3) state, which reveals paths to photodissociation following C–O stretch and C–O–H angle opening.},
doi = {10.1063/1.5079549},
journal = {Journal of Chemical Physics},
number = 11,
volume = 150,
place = {United States},
year = {2019},
month = {3}
}

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Works referenced in this record:

NWChem: A comprehensive and scalable open-source solution for large scale molecular simulations
journal, September 2010

  • Valiev, M.; Bylaska, E. J.; Govind, N.
  • Computer Physics Communications, Vol. 181, Issue 9, p. 1477-1489
  • DOI: 10.1016/j.cpc.2010.04.018