Photo-Fluorescence Decay Times of Organic Phosphors
J B Birks; W A Little; J B Birks; Physics Department, Rhodes University, Grahamstown, South Africa; W A Little; Physics Department, Rhodes University, Grahamstown, South Africa
Журнал:
Proceedings of the Physical Society. Section A
Дата:
1953-10-01
Аннотация:
A method for measuring photo-fluorescence decay times to approximately 10<sup>-9</sup> sec is described. Observations are made of the phase and modulation of the light from a 7.5 Mc/s air discharge tube, and of the fluorescence excited by this light, using a photomultiplier modulated at 15 Mc/s. The decay times of anthracene, stilbene, terphenyl and diphenylacetylene crystals of various thicknesses have been measured. Due to the overlap of the emission and absorption spectra, the technical decay time t<sub>f</sub> of a thick crystal is greater than the molecular decay time (t<sub>f</sub>)<sub>0</sub> observed for a microcrystalline specimen. For anthracene t<sub>f</sub>=14±2 mμsec and (t<sub>f</sub>)<sub>0</sub>=3.5±1.0 mμsec. This value of t<sub>f</sub> agrees with that derived from (t<sub>f</sub>)<sub>0</sub> and the comparative technical and molecular emission spectra. For each of the compounds studied the molecular decay time (t<sub>f</sub>)<sub>00</sub>, in the absence of internal quenching, is of the order of 3-4 mμsec.
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