Abstract
Pyridines are known to have different pKa* in the excited state from pKa in the ground state. They are easily protonated in their photo-excited states. In previous studies, we reported the luminescence properties of thin films of a pyridine-containing polymer, poly(4-vinylpyridine)(P4VPy). In this study, the changes in emission spectra of bulk solid and thin films of P4VPy with UV-irradiation are reported, and the influence of the film thickness of P4VPy is re-examined taking the effect of surface protonation into consideration. Though protonation of P4VPy has been reported many times, and the proton source are inside of the polymer, the surface protonation of P4VPy in this study are caused by the extrinsic, outer proton sources.
