COMPARATIVE-STUDY OF SOLID-MATRIX LUMINESCENCE INTERACTIONS OF P-AMINOBENZOATE ON 2 DIFFERENT MATRICES

The luminescence properties of the anion of p-aminobenzoic acid adsorbed on sodium acetate and filter paper were compared to gain Insights into the Interactions that result in the fluorescence and phosphorescence of p-aminobenzoate. Fluorescence quantum yields, phosphorescence quantum yields, and phosphorescence lifetimes were obtained for the anion of p-aminobenzoic acid adsorbed on filter paper. Preexponential and activation energy terms were calculated for p-aminobenzoate on filter paper and compared with similar terms for p-aminobenzoate adsorbed on sodium acetate. It was shown that there was a simple relationship between the reciprocal of the phosphorescence lifetimes and the thermal processes that cause deactivation of the triplet state. It was concluded that p-aminobenzoate is incorporated into the crystal structure of sodium acetate and the triplet energy of p-aminobenzoate was lost primarily via skeletal vibrations in NaOAc. For the anion of p-aminobenzoic acid on filter paper, some of the triplet energy was lost through vibrational modes In the filter paper, although other factors would also be involved in the loss of the triplet-state energy. © 1990, American Chemical Society. All rights reserved.