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Proceedings Paper

Paths of deactivation of excitation of chlorophyll a in various model systems
Author(s): Danuta Frackowiak; Bogumil Zelent; Henryk M. Malak; Roman Cegielski; Alfons Planner; Jacek Goc; Malgorzata Niedbalska
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Paper Abstract

Chlorophyll a (Chl) in most model systems (monolayers, fluid solvents, adsorbed layers, and polymer films) occurs in three forms: `dry monomers' (isolated from interaction with water), hydrated dimers and oligomers built from such dimers; but in nematic liquid crystal (LC) cell `dry monomers' are predominant. It is a competition between the various paths of deactivation of excited Chl. Excitation energy can be emitted as fluorescence, or delayed luminescence, transferred to other forms of Chl (ET), thermally deactivated or used for photochemical reactions. In order to compare the efficiency of these various paths the following measurements were done and analyzed: absorption, fluorescence, fluorescence excitation, photoacoustic spectra, and lifetime of fluorescence in ps range. There are some important differences between Chl in LC cell and polymer films: Chl in LC cell has a much lower concentration of aggregated forms and the pigment molecules are more uniformly distributed as compared to the Chl in polymer samples. To explain ET in polymer films the fractals model has to be used, whereas mean distances between solvated Chl molecules in LC can be obtained from dye concentration. In order to establish the interaction between Chl a and (beta) -carotene the LC cell with both pigments were also investigated.

Paper Details

Date Published: 17 August 1994
PDF: 8 pages
Proc. SPIE 2137, Time-Resolved Laser Spectroscopy in Biochemistry IV, (17 August 1994); doi: 10.1117/12.182775
Show Author Affiliations
Danuta Frackowiak, Poznan Technical Univ. (Poland)
Bogumil Zelent, Univ. of Maryland/Baltimore School of Medicine (United States)
Henryk M. Malak, Univ. of Maryland/Baltimore School of Medicine (United States)
Roman Cegielski, Poznan Technical Univ. (Poland)
Alfons Planner, Poznan Technical Univ. (Poland)
Jacek Goc, Poznan Technical Univ. (Poland)
Malgorzata Niedbalska, Poznan Technical Univ. (Poland)

Published in SPIE Proceedings Vol. 2137:
Time-Resolved Laser Spectroscopy in Biochemistry IV
Joseph R. Lakowicz, Editor(s)

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