Eosin Thermoluminescence in Polyvinyl Alcohol Films After Doubl Vis-IR Laser Excitation in a Wide Temperature Range

We developed an experimental technique of double stationary visible (l = 532 nm) and pulsed infrared (l = 10.6 μm) laser excitation of the electron-vibrational singlet and triplet states of eosin molecules in polyvinyl alcohol. After infrared excitation, delayed fluorescence (τdf ≈ 0.15 s) and thermoluminescence (τТL = 4.7 s) of eosin molecules in polymer matrix occur. The rate constants of these processes depend on the temperature and the presence of water in the polymer. The kinetics of low-temperature processes of thermoluminescence generation and quenching after IR laser pulse is studied. Two characteristic stages of the processes with different activation energies of thermoluminescence are determined: film heating in the 80–270 K temperature range (57.4 J/mol) and ice melting in the polymer matrix within the 270–330 K temperature interval (13.3 kJ/mol).