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Title: Two-photon excitation spectrum of light-harvesting complex II and fluorescence upconversion after one- and two-photon excitation of the carotenoids

Abstract

The two-photon excitation (TPE) spectrum of light-harvesting complex II (LHC II) has been measured in the spectral region of 1,000--1,600 nm, corresponding to one-photon wavelengths of 500--800 nm. The authors observed a band with an origin at {approximately}2 x 660 nm (ca. 15,100 {+-} 300 cm{sup {minus}1}) and a maximum at {approximately}2 x 600 nm. The line shape and origin of this band strongly suggest that the observed signal is due to the two-photon-allowed S{sub 1} state of the energy-transferring carotenoids (Car ) in LHC II. The authors also report the time dependence of the upconverted chlorophyll (Chl) fluorescence after TPE at the maximum of the observed band. Surprisingly, a fast rise of 250 {+-} 50 fs followed by a multiexponential decay on the picosecond time scale was observed. This result provides strong indication that there is a fast energy transfer even from the dipole-forbidden Car S{sub 1} state to the Chl's. The sub picosecond energy transfer from the Car S{sub 1} state is likely a consequence of the large number of energy-accepting Chls in van der Waals contact with the central Car's in LHC II. They also present upconversion data of the Car S{sub 2}, Chl a, and Chlmore » b fluorescence observed after one-photon excitation into the dipole-allowed Car S{sub 2} state. The lifetime of the Car S{sub 2} state is {approximately}120 {+-} 30 fs. With the observed time constants they are able to calculate quantum yields for the different possible pathways contributing to the overall Car to Chl energy transfer in LHC II.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Univ. of California, Berkeley, CA (US); Lawrence Berkeley National Lab., CA (US)
Sponsoring Org.:
USDOE; Deutsche Forschungsgemeinschaft DFG (German Research Partnership)
OSTI Identifier:
20075911
DOE Contract Number:  
AC03-76SF00098
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical
Additional Journal Information:
Journal Volume: 104; Journal Issue: 19; Other Information: PBD: 18 May 2000; Journal ID: ISSN 1089-5647
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 59 BASIC BIOLOGICAL SCIENCES; PROTEINS; PHOTOSYNTHESIS; CAROTENOIDS; EXCITATION; PHOTONS; FLUORESCENCE

Citation Formats

Walla, P.J., Yom, J., Krueger, B.P., and Fleming, G.R. Two-photon excitation spectrum of light-harvesting complex II and fluorescence upconversion after one- and two-photon excitation of the carotenoids. United States: N. p., 2000. Web. doi:10.1021/jp9943023.
Walla, P.J., Yom, J., Krueger, B.P., & Fleming, G.R. Two-photon excitation spectrum of light-harvesting complex II and fluorescence upconversion after one- and two-photon excitation of the carotenoids. United States. doi:10.1021/jp9943023.
Walla, P.J., Yom, J., Krueger, B.P., and Fleming, G.R. Thu . "Two-photon excitation spectrum of light-harvesting complex II and fluorescence upconversion after one- and two-photon excitation of the carotenoids". United States. doi:10.1021/jp9943023.
@article{osti_20075911,
title = {Two-photon excitation spectrum of light-harvesting complex II and fluorescence upconversion after one- and two-photon excitation of the carotenoids},
author = {Walla, P.J. and Yom, J. and Krueger, B.P. and Fleming, G.R.},
abstractNote = {The two-photon excitation (TPE) spectrum of light-harvesting complex II (LHC II) has been measured in the spectral region of 1,000--1,600 nm, corresponding to one-photon wavelengths of 500--800 nm. The authors observed a band with an origin at {approximately}2 x 660 nm (ca. 15,100 {+-} 300 cm{sup {minus}1}) and a maximum at {approximately}2 x 600 nm. The line shape and origin of this band strongly suggest that the observed signal is due to the two-photon-allowed S{sub 1} state of the energy-transferring carotenoids (Car ) in LHC II. The authors also report the time dependence of the upconverted chlorophyll (Chl) fluorescence after TPE at the maximum of the observed band. Surprisingly, a fast rise of 250 {+-} 50 fs followed by a multiexponential decay on the picosecond time scale was observed. This result provides strong indication that there is a fast energy transfer even from the dipole-forbidden Car S{sub 1} state to the Chl's. The sub picosecond energy transfer from the Car S{sub 1} state is likely a consequence of the large number of energy-accepting Chls in van der Waals contact with the central Car's in LHC II. They also present upconversion data of the Car S{sub 2}, Chl a, and Chl b fluorescence observed after one-photon excitation into the dipole-allowed Car S{sub 2} state. The lifetime of the Car S{sub 2} state is {approximately}120 {+-} 30 fs. With the observed time constants they are able to calculate quantum yields for the different possible pathways contributing to the overall Car to Chl energy transfer in LHC II.},
doi = {10.1021/jp9943023},
journal = {Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical},
issn = {1089-5647},
number = 19,
volume = 104,
place = {United States},
year = {2000},
month = {5}
}