Probing near-infrared photorelaxation pathways in eumelanins and pheomelanins.
Abstract
Ultraviolet-visible spectroscopy readily discerns the two types of melanin pigments
(eumelanin and pheomelanin), although fundamental details regarding the optical properties
and pigment heterogeneity are more difficult to disentangle via analysis of the broad
featureless absorption spectrum alone. We employed nonlinear transient absorption
spectroscopy to study different melanin pigments at near-infrared wavelengths. Excited-state
absorption, ground-state depletion, and stimulated emission signal contributions were
distinguished for natural and synthetic eumelanins and pheomelanins. A starker contrast
among the pigments is observed in the nonlinear excitation regime because they all
exhibit distinct transient absorptive amplitudes, phase shifts, and nonexponential
population dynamics spanning the femtosecond-nanosecond range. In this manner, different
pigments within the pheomelanin subclass were distinguished in synthetic and human
hair samples. These results highlight the potential of nonlinear spectroscopies to
deliver an in situ analysis of natural melanins in tissue that are otherwise difficult
to extract and purify.
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https://hdl.handle.net/10161/4073Published Version (Please cite this version)
10.1021/jp103608dPublication Info
Piletic, Ivan R; Matthews, Thomas E; & Warren, Warren S (2010). Probing near-infrared photorelaxation pathways in eumelanins and pheomelanins. J Phys Chem A, 114(43). pp. 11483-11491. 10.1021/jp103608d. Retrieved from https://hdl.handle.net/10161/4073.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
Warren S. Warren
James B. Duke Distinguished Professor of Chemistry
Our work focuses on the design and application of what might best be called novel
pulsed techniques, using controlled radiation fields to alter dynamics. The heart
of the work is chemical physics, and most of what we do is ultrafast laser spectroscopy
or nuclear magnetic resonance. It generally involves an intimate mixture of theory
and experiment: recent publications are roughly an equal mix of pencil- and-paper
theory, computer calculations with our workstations, and experiments. Collabo

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