Room temperature phosphorescence of coumarin 106 with direct triplet state excitation

Abstract

We report an efficient room temperature phosphorescence from coumarin 106 embedded in poly (vinyl alcohol) film. In addition to the excitation at 365 nm, within the absorption to the first singlet excited state, we observed the coumarin 106 phosphorescence excited directly to the triplet state at 465 nm, well outside the absorption band. Phosphorescence spectra, phosphorescence lifetimes, and temperature dependence of phosphorescence intensities are similar at UV and blue excitations. However, the phosphorescence emission anisotropies are very different. Whereas the phosphorescence anisotropy with UV excitation is low/negative, the direct triplet excitation results in high positive emission anisotropy.