Matrix effects in erythrosine sensitized photolysis of diazo compounds

Investigations have been made on erythrosine sensitized photolysis of 4-diethylaminobenzene diazonium salt 1 and 2-diazo-1-oxo-1,2-dihydronaphthalene 2 in polymeric binders of different glass transition temperatures (T_g 30–185°C). In the case of 1 the efficiency of photolysis as well as the quenching of direct and delayed fluorescence increase with decreasing T_g; in the case of 2, however, they increase with increasing T_g. The addition of plasticizers causes analogous effects. It is assumed that the sensitization of 1 occurs preferentially from the S₁-state, whilst in case of 2 it is from the T₁-state of erythrosine. Probability calculations reveal that the effective concentrations of the reactants within the critical radius of electron transfer are low, accounting for the low efficiency of the sensitized photolysis.