Transition dipole strength of eumelanin

Riesz, J. J., Gilmore, J. B., McKenzie, R. H., Powell, B. J., Pederson, M. R. and Meredith, P. (2007) Transition dipole strength of eumelanin. Physical Review E, 76 2: 021915-1-021915-10. doi:10.1103/PhysRevE.76.021915

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Author Riesz, J. J.
Gilmore, J. B.
McKenzie, R. H.
Powell, B. J.
Pederson, M. R.
Meredith, P.
Title Transition dipole strength of eumelanin
Journal name Physical Review E   Check publisher's open access policy
ISSN 1539-3755
Publication date 2007-08-15
Year available 2007
Sub-type Article (original research)
DOI 10.1103/PhysRevE.76.021915
Open Access Status File (Publisher version)
Volume 76
Issue 2
Start page 021915-1
End page 021915-10
Total pages 10
Editor Crest, G.S.
Malloy, M.
Place of publication United States
Publisher American Physical Society
Collection year 2008
Language eng
Subject 240202 Condensed Matter Physics - Structural Properties
780102 Physical sciences
09 Engineering
02 Physical Sciences
Abstract We report the transition dipole strength of eumelanin (the principal human photoprotective pigment) in the ultraviolet and visible. We have used both theoretical (density functional) and experimental methods to show that eumelanin is not an unusually strong absorber amongst organic chromophores. This is somewhat surprising given its role as a photoprotectant, and suggests that the dark coloring in vivo (and in vitro) of the eumelanin pigment is a concentration effect. Furthermore, by observing the polymerization of a principle precursor (5,6-dihydroxyindole-2-carboxylic acid) into the full pigment, we observe that eumelanin exhibits a small amount (similar to 20%) of hyperchromism (i.e., the reaction process enhances the light absorption ability of the resultant macromolecule relative to its monomeric precursor). These results have significant implications for our understanding of the photophysics of these important functional biomolecules. In particular, they appear to be consistent with the recently proposed chemical disorder secondary structure model of eumelanins.
Keyword Physics, Mathematical
Density-functional Calculations
Dissolved Organic-matter
5,6-dihydroxyindole-2-carboxylic Acid
Physics, Fluids & Plasmas
Quantum Yields
Band Model
Q-Index Code C1

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Created: Mon, 07 Apr 2008, 14:24:06 EST by Jenny Robinson on behalf of School of Mathematics & Physics