Estimation of the fluorescence lifetime for optically inaccessible exciplexes in nonpolar solutions under ionizing irradiation
Published in Photochemical Photobiological Sciences, 2016
X-irradiation of nonpolar solutions likely provides a possibility to create exciplexes for any donor–acceptor pair that would energetically and sterically allow this. Thorough study and characterization of X-radiation generated exciplexes usually cannot be carried out with conventional methods because of the complex and non-exponential formation and decay dynamics of these species. In this paper, we present a simple and universal experimental approach for the estimation of fluorescence lifetimes (τF) of X-radiation generated exciplexes. The suggested procedure is based on the comparison of quenching of the exciplex emission band and the emission band from a standard luminophore with a known excited state lifetime by dissolved oxygen. Using this approach we report the τF values for two systems with optically inaccessible exciplexes, diphenylacetylene–N,N-dimethylaniline (DMA) and p-terphenyl–DMA, and for two typical exciplex forming systems, naphthalene–DMA and anthracene–DMA. All the found τF values for the X-radiation generated exciplexes lie in the range of 50–70 ns. The accuracy of this approach was checked by time-resolved measurements under X- or near-UV irradiation for those pairs, whose properties make this feasible. The proposed method gives a possibility to avoid a complex numerical evaluation of the non-exponential kinetics of recombination luminescence, and can be used to estimate the characteristic τF values for luminophores and excited complexes formed under X-radiation.
Recommended citation: Melnikov A.R., Kalneus E.V., Korolev V.V., Sherin P.S., Borovkov V.I., Stass D.V. "Estimation of the fluorescence lifetime for optically inaccessible exciplexes in nonpolar solutions under ionizing irradiation" Photochem. Photobiol. Sci.. 2016. 15(6). P. 767-778.
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