Effect of Changes in Solution Structure on the Phosphorescence of Acenaphthene in Supercooled Toluene During Heating

Abstract

Changes in the phosphorescence intensity of acenaphthene in supercooled toluene during solution heating at a rate of 0.04 K/s at concentrations of 2 · 10^–3 and 2 · 10^–2 mol/L are studied. It is shown that when the glass transition temperature of toluene T_g = 117 K is reached, effective quenching of phosphorescence by oxygen begins for both solution concentrations. At the temperature of T = 130 K, an increase in intensity begins due to the appearance of a crystalline phase. The values of these temperatures are the same for both concentrations. For the solution concentration of 2 · 10^–3 mol/L at T = 140 K, an “explosive” increase in intensity is observed due to self-acceleration of toluene crystallization. For the solution concentration of 2 · 10^–2 mol/L, such changes are not observed. Possible causes of the established changes in the phosphorescence intensity and using this effect for studies of structural changes in supercooled organic solvents are discussed.