Spectroscopy and Dynamics of YD2-o-C8 in Solution and Interacting with Alumina Nanoparticles Electrode

Abstract

In this paper, we report on the absorption, emission, and photodynamics of a push–pull zinc porphyrin (YD2-o-C8) in solution and adsorbed on Al2O3 (alumina) nanoparticles (NPs). The shift in the absorption and emission spectra for the dye adsorbed on alumina NPs with respect to the solution suggests the presence of an anchoring effect of the dye to the NPs’ surface. Indeed, different molecular populations (monomers and aggregates) coexist for the solid film, as it is confirmed by both steady-state and time-resolved measurements. The emission decays, while monoexponential in acetonitrile (ACN) solution (τ = 1.5 ns) become multiexponential (140 and 550 ps) for the dye interacting with the alumina NPs. These lifetime values increase (210 and 930 ps) upon addition of CDCA (a disaggregating agent). The deactivation (vibrational cooling) of the hot S1 to cold S1 state, which occurs in 4–6 ps in ACN, shows a biexponential behavior in the solid state (2 ps, 20 ps). These two ps components, whose values upon excit...