Pulsed laser excited fluorescence of fluoranthene
Abstract
A pulsed laser spectroscopy system has been designed, constructed, and applied to the study of the dual fluorescence of fluoranthene. The apparatus incorporates a pulsed molecular nitrogen gas laser, or nitrogen laser pumped dye laser, associated electronics spectrometer, and data processing electronics. The completed experimental arrangement allows for the measurment of energy (wavelength) resolved spectra as well as the determination of decay times - time resolved spectra. The experimental system allows for the detection of fluorescence with higher spectral resolution than is generally possible with conventional excitation sources. The time resolved and energy resolved spectra of the dual fluorescence of fluoranthene have been characterized. The energy resolved spectrum consists of two easily discernable regions. The s region (S₂a->S₀ ) at 3700A to 3950A where the major contribution to the fluorescence originates from transitions [symbols in PDF] to totally symmetric vibronic components of the ground state and the Z region (S₁->S₀ ) at 4050A to approximately 5400A which represents to contribution to the emission which arises from transitions [symbols in PDF] to nontotally symmetric components [symbols in PDF] of the ground electronic state. The decay characteristics of the vibronic lines in the two regions have been determined. Typical of the s region is an anomalously long 140 nsec lifetime compared to a theoretical lifetime of approximately 20 nsec, and typical of the l region is a lifetime of 58 nsec. These results are in good agreement with theoretical predictions for the intermediate level spacing, strong coupling situation. In each region there are observed short lived lines (lifetimes of from 5 to 34 nsec) which come from unrelaxed excited vibrational levels of the excited electronic states. The anomalous phosphorescence (wavelength resolved only) of fluoranthene has also been observed.
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Citation
Philen, Dan Lassiter (1975). Pulsed laser excited fluorescence of fluoranthene. Texas A&M University. Texas A&M University. Libraries. Available electronically from https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -184139.