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Proceedings Paper

Femtosecond two-photon-excited fluorescence of melanin
Author(s): Klaus Teuchner; Susanne Mueller; Wolfgang Freyer; Dieter Leupold; Peter Altmeyer; Markus Stuecker; Klaus Hoffmann
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Paper Abstract

Spectral and time-resolved fluorescence studies of different eumelanins (natural, synthetic, enzymatic) in solution have been carried out by two-photon excitation at 800 nm, using 80 fs pulses with photon flux densities ≤ 1027 cm-2.s-1. Whereas all samples show monotonously decreasing absorption between near UV and near IR, their fluorescence behavior indicates strong heterogeneity. With respect to the also measured one-photon excited fluorescence (OPF) of melanin at 400 nm, the overall spectral shape of the two-photon excited fluorescence (TPF) is red-shifted. Both OPF and TPF exhibit three-exponential decay with a shortest component £ 200 ps. As is also shown, the fluorescence properties of melanin are dependent on the micro-environment. This allows the hypothesis, that the process of malignant transformation in skin tissue could be reflected in the fluorescence, provided the melanin in skin is selectively excited. The latter is realized by the described stepwise absorption of two 800 nm photons. In this way, indeed characteristic differences between the TPF spectra of healthy tissue, nevus cell nevi and malignant melanoma have been found.

Paper Details

Date Published: 14 February 2003
PDF: 9 pages
Proc. SPIE 4797, Multiphoton Absorption and Nonlinear Transmission Processes: Materials, Theory, and Applications, (14 February 2003); doi: 10.1117/12.453312
Show Author Affiliations
Klaus Teuchner, Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy (Germany)
Ruhr-Univ. Bochum (Germany)
Susanne Mueller, Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy (Germany)
Wolfgang Freyer, Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy (Germany)
Dieter Leupold, Max-Born-Institute for Nonlinear Optics and Short Pulse Spectroscopy (Germany)
Peter Altmeyer, Ruhr-Univ. Bochum (Germany)
Markus Stuecker, Ruhr-Univ. Bochum (Germany)
Klaus Hoffmann, Ruhr-Univ. Bochum (Germany)


Published in SPIE Proceedings Vol. 4797:
Multiphoton Absorption and Nonlinear Transmission Processes: Materials, Theory, and Applications
A. Todd Yeates; Kevin D. Belfield; Stephen J. Caracci; Christopher M. Lawson; Francois Kajzar; A. Todd Yeates; Kevin D. Belfield; Stephen J. Caracci, Editor(s)

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