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Dynamics of Excited States of the Carotenoid Peridinin in Polar Solvents: Dependence on Excitation Wavelength, Viscosity, and Temperature.

Zigmantas, Donatas LU ; Hiller, R G; Yartsev, Arkady LU ; Sundström, Villy LU and Polivka, Tomas LU (2003) In The Journal of Physical Chemistry Part B 107(22). p.5339-5348
Abstract
The dynamics of the excited states of the carotenoid peridinin in polar solvents were studied using femtosecond transient absorption spectroscopy in the spectral range of 500-1900 nm. A broadening of the absorption spectrum in polar solvents is caused by a distribution of conformers having different ground-state properties. In addition, the dependence of the peridinin lifetime on the excitation wavelength reveals that two peridinin forms coexist in protic solvents, where a "red"-absorbing form is produced by hydrogen bonding via the carbonyl group. The observed dynamics show that the S1 and intramolecular charge transfer (ICT) states of peridinin are strongly coupled, forming a collective S1/ICT state whose lifetime is determined by the... (More)
The dynamics of the excited states of the carotenoid peridinin in polar solvents were studied using femtosecond transient absorption spectroscopy in the spectral range of 500-1900 nm. A broadening of the absorption spectrum in polar solvents is caused by a distribution of conformers having different ground-state properties. In addition, the dependence of the peridinin lifetime on the excitation wavelength reveals that two peridinin forms coexist in protic solvents, where a "red"-absorbing form is produced by hydrogen bonding via the carbonyl group. The observed dynamics show that the S1 and intramolecular charge transfer (ICT) states of peridinin are strongly coupled, forming a collective S1/ICT state whose lifetime is determined by the degree of ICT character. In nonpolar solvent, pure S1 character with a lifetime of ~160 ps is observed, whereas in polar solvents an increase in the ICT character leads to a lifetime as short as 10 ps in methanol and 13 ps in ethylene glycol. In protic solvents, the ICT character of the S1/ICT state of the red peridinin form is further enhanced by hydrogen bonding, resulting in lifetimes shorter than 6 ps. A weak dependence of peridinin dynamics on viscosity shows that the ICT state is not formed via a twisted ICT mechanism. At 190 K in methanol, a significant increase in the S1/ICT lifetime is observed, suggesting that thermal coupling is involved in the S1/ICT state mixing. At 77 K in ethylene glycol glass, a multiexponential decay is revealed, indicating the presence of several conformers with different S1/ICT state properties. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
The Journal of Physical Chemistry Part B
volume
107
issue
22
pages
5339 - 5348
publisher
The American Chemical Society
external identifiers
  • wos:000183223500032
  • scopus:0038171507
ISSN
1520-5207
DOI
10.1021/jp0272318
language
English
LU publication?
yes
id
21b8efa2-7a97-4a26-95b8-c943f0183490 (old id 128243)
date added to LUP
2007-07-04 09:12:18
date last changed
2017-11-12 04:04:18
@article{21b8efa2-7a97-4a26-95b8-c943f0183490,
  abstract     = {The dynamics of the excited states of the carotenoid peridinin in polar solvents were studied using femtosecond transient absorption spectroscopy in the spectral range of 500-1900 nm. A broadening of the absorption spectrum in polar solvents is caused by a distribution of conformers having different ground-state properties. In addition, the dependence of the peridinin lifetime on the excitation wavelength reveals that two peridinin forms coexist in protic solvents, where a "red"-absorbing form is produced by hydrogen bonding via the carbonyl group. The observed dynamics show that the S1 and intramolecular charge transfer (ICT) states of peridinin are strongly coupled, forming a collective S1/ICT state whose lifetime is determined by the degree of ICT character. In nonpolar solvent, pure S1 character with a lifetime of ~160 ps is observed, whereas in polar solvents an increase in the ICT character leads to a lifetime as short as 10 ps in methanol and 13 ps in ethylene glycol. In protic solvents, the ICT character of the S1/ICT state of the red peridinin form is further enhanced by hydrogen bonding, resulting in lifetimes shorter than 6 ps. A weak dependence of peridinin dynamics on viscosity shows that the ICT state is not formed via a twisted ICT mechanism. At 190 K in methanol, a significant increase in the S1/ICT lifetime is observed, suggesting that thermal coupling is involved in the S1/ICT state mixing. At 77 K in ethylene glycol glass, a multiexponential decay is revealed, indicating the presence of several conformers with different S1/ICT state properties.},
  author       = {Zigmantas, Donatas and Hiller, R G and Yartsev, Arkady and Sundström, Villy and Polivka, Tomas},
  issn         = {1520-5207},
  language     = {eng},
  number       = {22},
  pages        = {5339--5348},
  publisher    = {The American Chemical Society},
  series       = {The Journal of Physical Chemistry Part B},
  title        = {Dynamics of Excited States of the Carotenoid Peridinin in Polar Solvents: Dependence on Excitation Wavelength, Viscosity, and Temperature.},
  url          = {http://dx.doi.org/10.1021/jp0272318},
  volume       = {107},
  year         = {2003},
}