Ibid. Chem. Phys. Nucleonics
- Ibid. Chem. Phys. Nucleonics
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 A from 2200A to 3300A. 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. For a given c, f = fl in region 1 ( A = 2500-2650 A), f = fi > fi in region 2 ( A = 2200-2350 A), and fi > f > fl for intermediate A. 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 10-11 sec, competes efficiently with conversion to the 1st excited state of toluene. f is found to depend on A.