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Proceedings Paper

Laser-induced fluorescence studies on collagen, cholesterol, and chlorophyll a
Author(s): Mihail-Lucian Pascu; N. Moise; S. Hogiu
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Paper Abstract

Results on laser induced fluorescence (LIF) properties of collagen, cholesterol and chlorophyll a (chl a) when excited at 337.1 nm are reported. The collagen and cholesterol florescence was studied in connection with atherosclerotic plaques diagnostics and/or removal within the cardiovascular system. The fluorescence signal excitation and collection were made using optical fibers, for liquid samples at concentrations between 0.1 mg/ml and 5.0 mg/ml for both collagen and cholesterol, their fluorescence lifetime being 5 nsec and 6 nsec, respectively. Chl a LIF concerned the stimulated emission of radiation considering the pigment as laser active medium. Chl a concentrations varied, in different solvents between 5 multiplied by 10-3 M/l and 10-5 M/l. For chl a at 0.62 mM/l and pumping photon densities higher than 5 multiplied by 1016 photons/cm2 and pulse, fluorescence linewidth narrowing from 28 nm to 5 nm in ethanol and from 25 nm to 4 nm in DMSO were obtained. Lasing maxima at 672 nm in acetone, 674 nm in ethanol and 678 nm in DMSO were observed. At lasing conditions for chl a in DMSO (1 mM/l) the measured fluorescence lifetime was 2 nsec instead of 5 nsec for normal fluorescence. The results on chl a stimulated emission show a lower lasing threshold at 1016 photons/cm2 and pulse, than previously reported, if DMSO solvent is used.

Paper Details

Date Published: 15 January 1996
PDF: 5 pages
Proc. SPIE 2630, Effects of Low-Power Light on Biological Systems, (15 January 1996); doi: 10.1117/12.230035
Show Author Affiliations
Mihail-Lucian Pascu, Institute of Atomic Physics (Romania)
N. Moise, Institute of Atomic Physics (Romania)
S. Hogiu, Institute of Atomic Physics (Romania)

Published in SPIE Proceedings Vol. 2630:
Effects of Low-Power Light on Biological Systems
Tiina I. Karu; Anthony R. Young, Editor(s)

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