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Excited states of carotenoid in LH2 : An ab initio study

He, Zhi LU ; Sundström, Villy LU and Pullerits, Tõnu LU (2001) In Chemical Physics Letters 334(1-3). p.159-167
Abstract

In order to understand the origin of ultrafast carotenoid bandshifts upon photoexcitation of bacteriochlorophyll (BChl) molecules in antenna complexes of photosynthetic purple bacteria, we have performed sa-CASSCF(8,7)/6-31G (and 6-31G*) calculations for the low-lying excited states of the carotenoid rhodopin glucoside (RG). The LH2 environment was simulated via atomic point charges to represent the electrostatic field of the ground and the Qy excited states of BChls near the carotenoid. The calculations showed that excitation of the B800 BChls yields a significant blue-shift of the carotenoid S2 energy in good agreement with experiments. We also found that the lowest triplet state energy of the RG is below 0.78... (More)

In order to understand the origin of ultrafast carotenoid bandshifts upon photoexcitation of bacteriochlorophyll (BChl) molecules in antenna complexes of photosynthetic purple bacteria, we have performed sa-CASSCF(8,7)/6-31G (and 6-31G*) calculations for the low-lying excited states of the carotenoid rhodopin glucoside (RG). The LH2 environment was simulated via atomic point charges to represent the electrostatic field of the ground and the Qy excited states of BChls near the carotenoid. The calculations showed that excitation of the B800 BChls yields a significant blue-shift of the carotenoid S2 energy in good agreement with experiments. We also found that the lowest triplet state energy of the RG is below 0.78 eV, which is lower than the energy of 1O2* (0.97 eV), in accord with the role of carotenoids as photoprotectors.

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publishing date
type
Contribution to journal
publication status
published
subject
in
Chemical Physics Letters
volume
334
issue
1-3
pages
9 pages
publisher
Elsevier
external identifiers
  • scopus:0001077862
ISSN
0009-2614
DOI
10.1016/S0009-2614(00)01338-5
language
English
LU publication?
yes
id
a6fa51f7-dfb7-4e38-8be3-7dc13e87f7ae
date added to LUP
2025-09-09 12:12:06
date last changed
2025-09-18 13:45:44
@article{a6fa51f7-dfb7-4e38-8be3-7dc13e87f7ae,
  abstract     = {{<p>In order to understand the origin of ultrafast carotenoid bandshifts upon photoexcitation of bacteriochlorophyll (BChl) molecules in antenna complexes of photosynthetic purple bacteria, we have performed sa-CASSCF(8,7)/6-31G (and 6-31G*) calculations for the low-lying excited states of the carotenoid rhodopin glucoside (RG). The LH2 environment was simulated via atomic point charges to represent the electrostatic field of the ground and the Q<sub>y</sub> excited states of BChls near the carotenoid. The calculations showed that excitation of the B800 BChls yields a significant blue-shift of the carotenoid S<sub>2</sub> energy in good agreement with experiments. We also found that the lowest triplet state energy of the RG is below 0.78 eV, which is lower than the energy of <sup>1</sup>O<sub>2</sub><sup>*</sup> (0.97 eV), in accord with the role of carotenoids as photoprotectors.</p>}},
  author       = {{He, Zhi and Sundström, Villy and Pullerits, Tõnu}},
  issn         = {{0009-2614}},
  language     = {{eng}},
  month        = {{02}},
  number       = {{1-3}},
  pages        = {{159--167}},
  publisher    = {{Elsevier}},
  series       = {{Chemical Physics Letters}},
  title        = {{Excited states of carotenoid in LH2 : An ab initio study}},
  url          = {{http://dx.doi.org/10.1016/S0009-2614(00)01338-5}},
  doi          = {{10.1016/S0009-2614(00)01338-5}},
  volume       = {{334}},
  year         = {{2001}},
}