ELECTRON TRANSFER FROM CHLOROPHYLL a TO QUINONE IN MONO‐ AND MULTILAYER ARRAYS

J. ‐P Dodelet, M. F. Lawrence, M. Ringuet, Roger Leblanc

Research output: Contribution to journalArticle

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Abstract

Abstract— Mono‐ and multilayers of chlorophyll a (Chl a)– lecithin have been prepared on quartz slides, by means of the Blodgett‐Langmuir technique, for fluorescence studies. Self‐quenching of the Chl a fluorescence has been observed in Chl a‐lecithin single layer excited with a laser light at 632.8 nm. The fluorescence yield is reduced by 50% at a concentration of 7 ± 1012 Chl a molecules cm−2. Chl a fluorescence quenching, by adding N,N‐distearoyl‐1,4‐diaminoanthraquinone (SAQ), has been studied. in a single layer, in pure Chl a and also at various dilutions of Chl a in lecithin. The results are explained in terms of a dynamic quenching rather than in terms of a permanent complex formation, at the ground state, between Chl a and SAQ. The fluorescence quenching has been interpreted as the result of an electron transfer from excited Chl a to SAQ, and rate constants of 8.3 ± 10−5 cm2 molecule−1 S−1 and 2.4 ± 10−4 cm2 molecule−1 s−1 have been found for pure diluted Chl a, respectively. Ten per cent of the diluted Chl a fluorescence always remains unquenchable and independent of the quinone concentration. In multilayers, where SAQ and Chl a are in different layers, there is no fluorescence quenching for pure or diluted Chl a even when the chromophores are in two adjacent layers. This happens only if SAQ is not able to diffuse from one layer to another. A minimum value of 22.4 nm has been found for the singlet exciton diffusion length in pure Chl a multilayers.

Original languageEnglish (US)
Pages (from-to)713-720
Number of pages8
JournalPhotochemistry and Photobiology
Volume33
Issue number5
DOIs
StatePublished - 1981
Externally publishedYes

Fingerprint

quinones
chlorophylls
electron transfer
Multilayers
Electrons
Fluorescence
fluorescence
Quenching
quenching
Lecithins
benzoquinone
chlorophyll a
Quartz
Chromophores
diffusion length
chutes
Ground state
chromophores
Dilution
dilution

ASJC Scopus subject areas

  • Biochemistry
  • Medicine(all)
  • Physical and Theoretical Chemistry

Cite this

ELECTRON TRANSFER FROM CHLOROPHYLL a TO QUINONE IN MONO‐ AND MULTILAYER ARRAYS. / Dodelet, J. ‐P; Lawrence, M. F.; Ringuet, M.; Leblanc, Roger.

In: Photochemistry and Photobiology, Vol. 33, No. 5, 1981, p. 713-720.

Research output: Contribution to journalArticle

Dodelet, J. ‐P ; Lawrence, M. F. ; Ringuet, M. ; Leblanc, Roger. / ELECTRON TRANSFER FROM CHLOROPHYLL a TO QUINONE IN MONO‐ AND MULTILAYER ARRAYS. In: Photochemistry and Photobiology. 1981 ; Vol. 33, No. 5. pp. 713-720.
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abstract = "Abstract— Mono‐ and multilayers of chlorophyll a (Chl a)– lecithin have been prepared on quartz slides, by means of the Blodgett‐Langmuir technique, for fluorescence studies. Self‐quenching of the Chl a fluorescence has been observed in Chl a‐lecithin single layer excited with a laser light at 632.8 nm. The fluorescence yield is reduced by 50{\%} at a concentration of 7 ± 1012 Chl a molecules cm−2. Chl a fluorescence quenching, by adding N,N‐distearoyl‐1,4‐diaminoanthraquinone (SAQ), has been studied. in a single layer, in pure Chl a and also at various dilutions of Chl a in lecithin. The results are explained in terms of a dynamic quenching rather than in terms of a permanent complex formation, at the ground state, between Chl a and SAQ. The fluorescence quenching has been interpreted as the result of an electron transfer from excited Chl a to SAQ, and rate constants of 8.3 ± 10−5 cm2 molecule−1 S−1 and 2.4 ± 10−4 cm2 molecule−1 s−1 have been found for pure diluted Chl a, respectively. Ten per cent of the diluted Chl a fluorescence always remains unquenchable and independent of the quinone concentration. In multilayers, where SAQ and Chl a are in different layers, there is no fluorescence quenching for pure or diluted Chl a even when the chromophores are in two adjacent layers. This happens only if SAQ is not able to diffuse from one layer to another. A minimum value of 22.4 nm has been found for the singlet exciton diffusion length in pure Chl a multilayers.",
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N2 - Abstract— Mono‐ and multilayers of chlorophyll a (Chl a)– lecithin have been prepared on quartz slides, by means of the Blodgett‐Langmuir technique, for fluorescence studies. Self‐quenching of the Chl a fluorescence has been observed in Chl a‐lecithin single layer excited with a laser light at 632.8 nm. The fluorescence yield is reduced by 50% at a concentration of 7 ± 1012 Chl a molecules cm−2. Chl a fluorescence quenching, by adding N,N‐distearoyl‐1,4‐diaminoanthraquinone (SAQ), has been studied. in a single layer, in pure Chl a and also at various dilutions of Chl a in lecithin. The results are explained in terms of a dynamic quenching rather than in terms of a permanent complex formation, at the ground state, between Chl a and SAQ. The fluorescence quenching has been interpreted as the result of an electron transfer from excited Chl a to SAQ, and rate constants of 8.3 ± 10−5 cm2 molecule−1 S−1 and 2.4 ± 10−4 cm2 molecule−1 s−1 have been found for pure diluted Chl a, respectively. Ten per cent of the diluted Chl a fluorescence always remains unquenchable and independent of the quinone concentration. In multilayers, where SAQ and Chl a are in different layers, there is no fluorescence quenching for pure or diluted Chl a even when the chromophores are in two adjacent layers. This happens only if SAQ is not able to diffuse from one layer to another. A minimum value of 22.4 nm has been found for the singlet exciton diffusion length in pure Chl a multilayers.

AB - Abstract— Mono‐ and multilayers of chlorophyll a (Chl a)– lecithin have been prepared on quartz slides, by means of the Blodgett‐Langmuir technique, for fluorescence studies. Self‐quenching of the Chl a fluorescence has been observed in Chl a‐lecithin single layer excited with a laser light at 632.8 nm. The fluorescence yield is reduced by 50% at a concentration of 7 ± 1012 Chl a molecules cm−2. Chl a fluorescence quenching, by adding N,N‐distearoyl‐1,4‐diaminoanthraquinone (SAQ), has been studied. in a single layer, in pure Chl a and also at various dilutions of Chl a in lecithin. The results are explained in terms of a dynamic quenching rather than in terms of a permanent complex formation, at the ground state, between Chl a and SAQ. The fluorescence quenching has been interpreted as the result of an electron transfer from excited Chl a to SAQ, and rate constants of 8.3 ± 10−5 cm2 molecule−1 S−1 and 2.4 ± 10−4 cm2 molecule−1 s−1 have been found for pure diluted Chl a, respectively. Ten per cent of the diluted Chl a fluorescence always remains unquenchable and independent of the quinone concentration. In multilayers, where SAQ and Chl a are in different layers, there is no fluorescence quenching for pure or diluted Chl a even when the chromophores are in two adjacent layers. This happens only if SAQ is not able to diffuse from one layer to another. A minimum value of 22.4 nm has been found for the singlet exciton diffusion length in pure Chl a multilayers.

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