A MODEL FOR THE NONRADIATIVE DECAY OF ORGANIC PHOSPHOR TRIPLET-STATESIN SOLID MATRICES

The heat capacities of sodium acetate/NaCl mixtures and 30% beta-cyclo dextrin/NaCl were obtained over a wide temperature range. These data i n addition to heat capacity data from the literature for sodium acetat e and NaCl were related to the phosphorescence lifetimes of several ph osphors adsorbed individually on sodium acetate, sodium acetate/NaCl, and 30% beta-cyclodextrin/NaCl. Several linear relationships were obta ined between a phosphorescence lifetime function and the reciprocal of the bulk heat capacity data for the phosphors adsorbed on the solid m atrices. In addition, consideration was given to the solid-matrix phos phorescence quantum yields of the phosphors. The relation ships develo ped were related to solid-state theories and organic luminescence theo ry. The bulk heat capacity had an influence on the phosphorescence lif etime, and low-frequency vibrational modes in the solid matrices were activating vibrational modes in the excited tripler state of the phosp hors which caused nonradiative transitions from the excited triplet st ate. These results have important implications in room-temperature sol id-matrix phosphorescence analysis because a model was developed that explains some of the details of the nonradiative transition from the e xcited triplet state of a phosphor adsorbed on a solid matrix.