Laser flash photolysis of benzophenone in thin silicone films

The decay kinetics of benzophenone (BP) triplet state in the thin (∼200 nm) films of poly(dimethylsiloxane) have been studied with a nanosecond laser flash photolysis technique. Decay kinetics of a triplet state of BP (3BP) is dispersive kinetics, and it can be well described by the kinetic law with Gaussian distribution of the activation free energy. The average rate constants of 3BP decay kav are 1500 and 70 s−1 for air saturated and deoxygenated films, respectively. Width of distribution are 1.2 and 4.3 (dimensionless) and correspond to the first and second kav, respectively presented above. The rate of hydrogen abstraction of H-atom from Si–CH3 groups by 3BP is low which results in long-lived 3BP in silicone films.