title: Self-quenching of uranin: Instrument response function for color sensitive photo-detectors.
abstract: Concentration is a key determining factor in the fluorescence properties of organic fluorophores. We studied self-quenching of disodium fluorescein (uranin) fluorescence in polyvinyl alcohol (PVA) thin films. The concentration dependent changes in brightness and anisotropy were followed by a lifetime decrease. We found that at a concentration of 0.54 M, the lifetime decreases to 7 ps. At a concentration of 0.18 M the lifetime was 10 ps with the relatively high quantum yield of 0.002. In these conditions the fluorescence intensity decay was homogeneous (well approximated by a single lifetime). We realized that such a sample was an ideal fluorescence lifetime standard for spectroscopy and microscopy, and therefore characterized instrument response functions for a time-domain technique. We show that self-quenched uranin enables measurements free of the color effect, making it a superior choice for a lifetime reference over scattered light.
authors.affiliation: Center for Commercialization of Fluorescence Technologies (CCFT), Department of Molecular Biology & Immunology, UNTHSC, Fort Worth, TX 76107, USA.
authors.forename: Rafal
authors.initials: R
authors.lastname: Luchowski
authors.forename: Sushant
authors.initials: S
authors.lastname: Sabnis
authors.forename: Mariusz
authors.initials: M
authors.lastname: Szabelski
authors.forename: Pabak
authors.initials: P
authors.lastname: Sarkar
authors.forename: Sangram
authors.initials: S
authors.lastname: Raut
authors.forename: Zygmunt
authors.initials: Z
authors.lastname: Gryczynski
authors.forename: Julian
authors.initials: J
authors.lastname: Borejdo
authors.forename: Piotr
authors.initials: P
authors.lastname: Bojarski
authors.forename: Ignacy
authors.initials: I
authors.lastname: Gryczynski