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Proceedings Paper

Time-resolved fluorescence and FCS studies of dye-doped DNA
Author(s): N. Nicolaou; R. J. Marsh; T. Blacker; D. A. Armoogum; A. J. Bain
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Paper Abstract

Fluorescence lifetime, anisotropy and intensity dependent single molecule fluorescence correlation spectroscopy (I-FCS) are used to investigate the mechanism of fluorescence saturation in a free and nucleotide bound fluorophore (NR6104) in an antioxidising ascorbate buffer. Nucleotide attachment does not appreciably affect the fluorescence lifetime of the probe and there is a decrease in the rate of intersystem crossing relative to that of triplet state deactivation. The triplet state fraction is seen to plateau at 72% (G-attached) and 80% (free fluorophore) in agreement with these observations. Measurements of translational diffusion times show no intensity dependence for excitation intensities between 1 and 105kW cm-2 and photobleaching is therefore negligible. The dominant mechanism of fluorescence saturation is thus triplet state formation. I-FCS measurements for Rhodamine 6G in water were compared with those in the ascorbate buffer. In water the triplet fraction was saturated at considerably higher powers (45% at ca. 1.5 × 103kW cm-2) than in the ascorbate buffer (55%ca. 1 1kW cm-2)

Paper Details

Date Published: 1 September 2009
PDF: 12 pages
Proc. SPIE 7393, Nanophotonic Materials VI, 73930L (1 September 2009); doi: 10.1117/12.826043
Show Author Affiliations
N. Nicolaou, Univ. College London (United Kingdom)
R. J. Marsh, Univ. College London (United Kingdom)
T. Blacker, Univ. College London (United Kingdom)
D. A. Armoogum, Univ. College London (United Kingdom)
A. J. Bain, Univ. College London (United Kingdom)

Published in SPIE Proceedings Vol. 7393:
Nanophotonic Materials VI
Stefano Cabrini; Taleb Mokari, Editor(s)

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