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Proceedings Paper

Nonlinear absorption of photons in biological molecules: initial studies of melanin
Author(s): Yue Han; Joseph S. Rosenshein; Zhouling Wu; Qiang Zhao; Tian Li Yang; Marshall Thomsen; Wen Ye
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Paper Abstract

Based on the mechanisms of sequential two-photon absorption in biological molecules, a theoretical model is proposed for the absorption of light in melanin. To test this model, melanin samples were studied using the collinear photothermal deflection spectroscopy (PDS), with an He-Ne laser and an Argon-Krypton ion laser to provide two simultaneously exciting wavelengths. It is found that melanin samples have a strong decay in amplitude of the photothermal signal, in contrast to a reference India ink whose photothermal signal is stable. The power dependence of the amplitude of the photothermal signal is also found to exhibit a departure from linearity at higher power densities for a melanin sample. Simultaneous exposure of the same sample to He-Ne and Argon-Krypton ion laser irradiation produces a signal which is significantly less than that expected from the sum of the signals obtained from using each laser alone. These results are explained with a modification of the sequential two-photon absorption process, which involves a conversion of the photon energy to a non- thermal form such as photochemical energy.

Paper Details

Date Published: 1 July 1998
PDF: 8 pages
Proc. SPIE 3245, Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems VIII, (1 July 1998); doi: 10.1117/12.312320
Show Author Affiliations
Yue Han, Oakland Univ. (United States)
Joseph S. Rosenshein, Oakland Univ. and Sinai Hospital of Detroit (United States)
Zhouling Wu, Eastern Michigan Univ. (United States)
Qiang Zhao, Eastern Michigan Univ. (United States)
Tian Li Yang, Eastern Michigan Univ. (United States)
Marshall Thomsen, Eastern Michigan Univ. (United States)
Wen Ye, Univ. of Michigan (United States)


Published in SPIE Proceedings Vol. 3245:
Lasers in Surgery: Advanced Characterization, Therapeutics, and Systems VIII
Graham M. Watson; Harvey Lui; Lou Reinisch; Penny J. Smalley; Kenneth Eugene Bartels; R. Rox Anderson; Lawrence S. Bass; Kenneth Eugene Bartels; C. Gaelyn Garrett; Lloyd P. Tate; Sharon L. Thomsen; Reza S. Malek; Aaron P. Perlmutter; R. Rox Anderson; Lawrence S. Bass; C. Gaelyn Garrett; Kenton W. Gregory; Harvey Lui; Reza S. Malek; Aaron P. Perlmutter; Lou Reinisch; Penny J. Smalley; Lloyd P. Tate; Sharon L. Thomsen; Graham M. Watson, Editor(s)

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