HIGH-PRESSURE STUDY OF FLEXIBLE FLUORESCENT DYE MOLECULES IN SOLID POLYMERIC MEDIA .2. POLYESTER YELLOW 6G-LSW

We have measured the luminescence efficiency of polyester 6G-LSW (PY) as a function of pressure in several polymeric matrices. The quenching of the luminescence is largely due to twisting distortion in the excited state. Two possible twists could be identified, one involving a malononitrile group and one a C-N-phenyl group on a side chain. From the pressure data we were able to separate these two twisting processes and to characterize them in terms of a parameter k(nr)' which is a function of the rates of crossing from the planar to the twisted conformation and the reverse process, and of the rate of thermal dissipation of energy from the twisted state.