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Proceedings Paper

Time-resolved fluorescence polarization spectroscopy of visible and near infrared dyes in picosecond dynamics
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Paper Abstract

Near-infrared (NIR) dyes absorb and emit light within the range from 700 to 900 nm have several benefits in biological studies for one- and/or two-photon excitation for deeper penetration of tissues. These molecules undergo vibrational and rotational motion in the relaxation of the excited electronic states, Due to the less than ideal anisotropy behavior of NIR dyes stemming from the fluorophores elongated structures and short fluorescence lifetime in picosecond range, no significant efforts have been made to recognize the theory of these dyes in time-resolved polarization dynamics. In this study, the depolarization of the fluorescence due to emission from rotational deactivation in solution will be measured with the excitation of a linearly polarized femtosecond laser pulse and a streak camera. The theory, experiment and application of the ultrafast fluorescence polarization dynamics and anisotropy are illustrated with examples of two of the most important medical based dyes. One is NIR dye, namely Indocyanine Green (ICG) and is compared with Fluorescein which is in visible range with much longer lifetime. A set of first-order linear differential equations was developed to model fluorescence polarization dynamics of NIR dye in picosecond range. Using this model, the important parameters of ultrafast polarization spectroscopy were identified: risetime, initial time, fluorescence lifetime, and rotation times.

Paper Details

Date Published: 9 March 2015
PDF: 12 pages
Proc. SPIE 9355, Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XV, 935517 (9 March 2015); doi: 10.1117/12.2076233
Show Author Affiliations
Yang Pu, The City College of New York (United States)
Robert R. Alfano, The City College of New York (United States)


Published in SPIE Proceedings Vol. 9355:
Frontiers in Ultrafast Optics: Biomedical, Scientific, and Industrial Applications XV
Alexander Heisterkamp; Peter R. Herman; Michel Meunier; Stefan Nolte, Editor(s)

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