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Proceedings Paper

Enhanced eumelanin emission by stepwise three-photon excitation
Author(s): Josef Kerimo; Milind Rajadhyaksha; Charles A. DiMarzio
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Paper Abstract

Eumelanin fluorescence from Sepia officinalis and black human hair was activated with near-infrared radiation and multiphoton excitation. A third order multiphoton absorption by a step-wise process appears to be the underlying mechanism. The activation was caused by a photochemical process since it could not be reproduced by simple heating. Both fluorescence and brightfield imaging indicate the near-infrared irradiation caused photodamage to the eumelanin and the activated emission originated from the photodamaged region. At least two different components with about thousand-fold enhanced fluorescence were activated and could be distinguished by their excitation properties. One component was excited with wavelengths in the visible region and exhibited linear absorption dependence. The second component could be excited with near-infrared wavelengths and had a third order dependence on the laser power. The third order dependence is explained by a step-wise excited state absorption (ESA) process since it could be observed equally with the CW and femtosecond lasers. The new method for photoactivating the eumelanin fluorescence was used to map the melanin content in human hair.

Paper Details

Date Published: 28 February 2011
PDF: 8 pages
Proc. SPIE 7903, Multiphoton Microscopy in the Biomedical Sciences XI, 79031X (28 February 2011); doi: 10.1117/12.873598
Show Author Affiliations
Josef Kerimo, Northeastern Univ. (United States)
Milind Rajadhyaksha, Memorial Sloan-Kettering Cancer Ctr. (United States)
Charles A. DiMarzio, Northeastern Univ. (United States)

Published in SPIE Proceedings Vol. 7903:
Multiphoton Microscopy in the Biomedical Sciences XI
Ammasi Periasamy; Karsten König; Peter T. C. So, Editor(s)

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