Energy Transfer in Organic Systems I: Photofluorescence of Terphenyl-toluene Solutions
J B Birks; A J W Cameron; J B Birks; Physics Department, Rhodes University, South Africa; A J W Cameron; Physics Department, Rhodes University, South Africa
Журнал:
Proceedings of the Physical Society
Дата:
1958-07-01
Аннотация:
The fluorescence quantum intensities of normal and oxygen-free solutions of para-terphenyl in toluene have been measured as a function of concentration c and of excitation wavelength λ from 2200 Å to 3300 Å. The absorption spectra of toluene and terphenyl have been observed. The energy transfer coefficient f from excited toluene molecules to terphenyl molecules has thus been obtained.f is found to depend on λ. For a given c, f=f<sub>1</sub> in region 1 (λ=2500-2650 Å), f=f<sub>2</sub>>f<sub>1</sub> in region 2 (λ=2200-2350 Å), and f<sub>2</sub>>f>f<sub>1</sub> for intermediate λ. Regions 1 and 2 correspond to the first and second excited electronic singlet states of toluene. The solvent-solute energy transfer from the second excited state, which occurs in approximately 10<sup>-11</sup> sec, competes efficiently with conversion to the 1st excited state of toluene.
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