Direct and Indirect Action on Thymine in Aqueous Solution by Powerful Laser Ultraviolet Radiation

It has been shown that the transformations of thymine in liquid aqueous solution under intense laser ultraviolet irradiation ( I 0 ≈ 10 12 -10 13 W/m 2 , λ = 266 and 316 nm) are conditioned mainly by two-quantum processes: reactions of the primary products of thymine photolysis with water (direct photolysis) and/or the action of the products of two-photon water photolysis on thymine (indirect photolysis). The ratio of the degrees of direct and indirect photolysis depends on the ratio of the energies absorbed by thymine and water. Despite a principal difference in the primary processes, the sets of final products of thymine transformation in both ways are qualitatively and quantitatively similar.