EXCITON LOCALIZATION IN THIN POLYMER-FILMS PROBED BY SELECTIVE FLUORESCENCE SPECTROSCOPY

We performed selective laser excitation of fluorescence of thin films of poly(p-phenylene) (PPP) at room and liquid helium temperatures. Mon ochromatic laser excitation becomes selective upon excitation below a threshold frequency of 22 400 cm(-1) in the low-energy tail of the flu orescence excitation band, 2200 cm(-1) below the maximum of the excita tion spectrum. The experimental results are interpreted on the basis o f model calculations.