The quantum efficiency of radiationless energy transfer from naphthalene to 9,10-diphenylanthracene (DPA) and from 2,5- diphenyloxazole to DPA has been observed as a function of acceptor concentration in deoxygenated solutions in benzene, cyclohexane, cyclohexanol and benzene-cyclohexanol mixtures. The results agree reasonably with the Yokota-Tamimoto relation for the effect of diffusion on Forster dipole-dipole transfer, but there is evidence that multipole-multipole interaction terms may increase in the critical transfer distance R0 when the latter is small.

Energy transfer in organic systems. IX. Effect of diffusion on transfer efficiency

Structural isomerization dynamics of photoexcited van der Waals dimers of toluene and benzene have been investigated by means of fluorescence and mass spectroscopic methods. Two isomeric forms of the heterodimer complex formed between toluene and benzene, assigned to parallel displaced and T-shaped configurations, are found to rearrange into exciplexes when excited in the S1 state with a small amount of vibrational energy. The toluene homodimer also reveals similar excess energy dependence on excimer formation. The excited-state dynamics are contrasted with those of the T-shaped benzene homodimer where no vibrational energy is required for structural isomerization. The excess energy dependence observed for the toluene complexes is attributed to a steric requirement of sandwich-type excimer geometry. Dissociation behavior of these exciplex/excimer complexes has been measured by photodepletion spectroscopy and compared with that of the benzene excimer. These excited-state complexes are found to strongly abs...

Excimer and Exciplex Formation in van der Waals Dimers of Toluene and Benzene

For pt. X see abstr. A26392 of 1971. The rate parameters of solvent-solute energy transfer, solvent excitation quenching and solute excitation quenching have been measured for the toluene-PPO-carbon tetrabromide system from -20 degrees C to +50 degrees C. The transfer and quenching rates are consistent within diffusion controlled processes with a solvent interaction radius of 3 times the molecular radius.

https://iopscience.iop.org/article/10.1088/0022-3700/4/11/015/pdf

Energy transfer in organic systems. XI. Temperature dependence of singlet excitation transfer and quenching in toluene solutions

Existence of a compensation law for internal quenching of fluorescence

/pdf/excitation-and-deexcitation-of-benzene-i73ne23dsi.pdf

Excitation and Deexcitation of Benzene

Observations of the fluorescence lifetimes and quantum yields of toluene solutions in n-hexane from -85 °c to 50 °c have been analysed to evaluate the molecular and excimer fluorescence and internal quenching rate parameters, their frequency factors and activation energies and other related parameters. An excimer binding energy of 029 ev is obtained.

https://iopscience.iop.org/article/10.1088/0022-3700/1/6/321/pdf

J R Greenleaf

Papers

Molecular and excimer fluorescence of toluene