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Title: Carotenoid Nuclear Reorganization and Interplay of Bright and Dark Excited States

Abstract

We report quantum chemical calculations using multireference perturbation theory (MRPT) with the density matrix renormalization group (DMRG) plus photothermal deflection spectroscopy measurements to investigate the manifold of carotenoid excited states and establish their energies relative to the bright state (S2) as a function of nuclear reorganization. We conclude that the primary photophysics and function of carotenoids are determined by interplay of only the bright (S2) and lowest-energy dark (S1) states. The lowest-lying dark state, far from being energetically distinguishable from the lowest-lying bright state along the entire excited-state nuclear reorganization pathway, is instead computed to be either the second or first excited state depending on what equilibrium geometry is considered. This result suggests that, rather than there being a dark intermediate excited state bridging a non-negligible energy gap from the lowest-lying dark state to the lowest-lying bright state, there is in fact no appreciable energy gap to bridge following photoexcitation. Instead, excited-state nuclear reorganization constitutes the bridge from S2 to S1, in the sense that these two states attain energetic degeneracy along this pathway.

Authors:
 [1];  [2];  [1];  [2]; ORCiD logo [2];  [3];  [3];  [1]
  1. Princeton University
  2. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
  3. University of Glasgow
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1571900
Report Number(s):
NREL/JA-5900-75239
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry B
Additional Journal Information:
Journal Volume: 123; Journal Issue: 41
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; multireference perturbation theory; density matrix renormalization group; carotenoid excited states; energies

Citation Formats

Taffet, Elliot J., Lee, Benjamin G, Toa, Zi S. D., Pace, Natalie, Rumbles, Garry, Southall, June, Cogdell, Richard J., and Scholes, Gregory D. Carotenoid Nuclear Reorganization and Interplay of Bright and Dark Excited States. United States: N. p., 2019. Web. doi:10.1021/acs.jpcb.9b04027.
Taffet, Elliot J., Lee, Benjamin G, Toa, Zi S. D., Pace, Natalie, Rumbles, Garry, Southall, June, Cogdell, Richard J., & Scholes, Gregory D. Carotenoid Nuclear Reorganization and Interplay of Bright and Dark Excited States. United States. doi:10.1021/acs.jpcb.9b04027.
Taffet, Elliot J., Lee, Benjamin G, Toa, Zi S. D., Pace, Natalie, Rumbles, Garry, Southall, June, Cogdell, Richard J., and Scholes, Gregory D. Wed . "Carotenoid Nuclear Reorganization and Interplay of Bright and Dark Excited States". United States. doi:10.1021/acs.jpcb.9b04027.
@article{osti_1571900,
title = {Carotenoid Nuclear Reorganization and Interplay of Bright and Dark Excited States},
author = {Taffet, Elliot J. and Lee, Benjamin G and Toa, Zi S. D. and Pace, Natalie and Rumbles, Garry and Southall, June and Cogdell, Richard J. and Scholes, Gregory D.},
abstractNote = {We report quantum chemical calculations using multireference perturbation theory (MRPT) with the density matrix renormalization group (DMRG) plus photothermal deflection spectroscopy measurements to investigate the manifold of carotenoid excited states and establish their energies relative to the bright state (S2) as a function of nuclear reorganization. We conclude that the primary photophysics and function of carotenoids are determined by interplay of only the bright (S2) and lowest-energy dark (S1) states. The lowest-lying dark state, far from being energetically distinguishable from the lowest-lying bright state along the entire excited-state nuclear reorganization pathway, is instead computed to be either the second or first excited state depending on what equilibrium geometry is considered. This result suggests that, rather than there being a dark intermediate excited state bridging a non-negligible energy gap from the lowest-lying dark state to the lowest-lying bright state, there is in fact no appreciable energy gap to bridge following photoexcitation. Instead, excited-state nuclear reorganization constitutes the bridge from S2 to S1, in the sense that these two states attain energetic degeneracy along this pathway.},
doi = {10.1021/acs.jpcb.9b04027},
journal = {Journal of Physical Chemistry B},
number = 41,
volume = 123,
place = {United States},
year = {2019},
month = {9}
}