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Time-resolved fluorescence spectroscopy of cationic dyes incorporated in silica matrix by high pressure compaction

Paper ID Volume ID Publish Year Pages File Format Full-Text
28527 44080 2006 5 PDF Available
Title
Time-resolved fluorescence spectroscopy of cationic dyes incorporated in silica matrix by high pressure compaction
Abstract

The cationic dyes 9-amino acridine (9AA) and auramine were incorporated into silica matrix by sol–gel method, producing transparent monoliths. These fluorochromic materials were converted into powder and compacted at room temperature at 6 GPa to form optical crack-free compact glasses. The dyes incorporated in these three forms (monolith, powder and compact glass) were studied by time-resolved fluorescence spectroscopy in order to obtain information of the excited state dynamics under soft and compressed silica environment. Both dyes have multi-exponential decays in these solid phases. 9AA in monolith and in silica powder shows biexponential decay with components of 8.4–9.0 and 23–24 ns. In compact glass, a fast component of 2.4 ns is detected in addition to the two cited slow components, and it has been ascribed to electronic energy migration among dyes and exciton trapping by dark dimers. For auramine, a dye that fluoresces in rigid matrix by precluding its fast intramolecular twisting and subsequent non-radiative deactivation, the three types of solids enhance the fluorescence signal and give rise to decay processes from picoseconds to nanoseconds in the time scale. In monolith and silica powder, the behavior is practically the same, with three decay components of 0.3, 1.3 and 4.3 ns. However, in compact glass, the two first decay components are shifted to larger values of 0.63 and 2.3 ns, while the third component remains practically constant with a value of 4.1 ns. These results are analyzed with the model of emissive and non-emissive states of auramine under restricted torsional molecular motion.

Keywords
Photophysics; Solid state; Glasses; Fluorescence decay; Organic dyes; High pressure
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Time-resolved fluorescence spectroscopy of cationic dyes incorporated in silica matrix by high pressure compaction
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 181, Issues 2–3, 31 July 2006, Pages 147–151
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us