PHOTOPHYSICAL PROPERTIES OF SOME THIENYL KETONES - AN EXPERIMENTAL AND THEORETICAL-STUDY

The absorption and emission properties of three thienyl ketones (pheny l 2-thienyl ketone, di-2-thienyl ketone, and cyclopenta[2,1-b:3,4-b']d ithiophen-7-one) were investigated in several solvents. By comparison of experimental results with CNDO/S calculations, the lowest electroni c transitions were assigned. Triplet-triplet transient spectra, triple t lifetimes, and quantum yields were determined. For the first two mol ecules, very effective spin-orbit coupling was found, and phosphoresce nce was observed in both fluid solutions and frozen glasses. For the c yclic ketone the dominating deactivation process was internal conversi on from the S-1 state to the ground state.