The anomalous phosphorescence excitation spectra of model lignin compounds

Abstract

The anomalous phosphorescence spectra of lignin model compounds at 77 K are explained in terms of the formation of molecular aggregates (K ≈ 50 mol^-1 1.). Aggregation best explains the phosphorescence excitation spectra and the increase in phosphorescence yield (Y_p) with increasing concentration; for example, for isosafrole in ethanol at 77 K, Y_p is less than 0.005 at 10^-5 M and c.0.1 at 3 × 10^-2 M.