Polarisation characteristics of excimer emissions from polymers in fluid media

The polarisation characteristics of the fluorescence of fluid solutions of polystyrene, poly(1-vinylnaphthalene), poly(2-vinylnaphthalene) and poly(acenaphthylene) have been examined over a range of concentrations and molecular weights. The emissions from the naphthalene-based polymers are totally depolarised within the timescales imposed by the excited state lifetime, as is to be expected for energy migration prior to trapping in excimer sites. The "excimer band" fluorescence of polystyrene can exhibit apparent positive degrees of polarisation at high concentrations (= 10^-2 M) and high molar mass. However it has been shown that these effects result from the influence of scattered radiation and, by using time-resolution to exclude the scatter, that the emission from the excimeric state of polystyrene is totally depolarised. © 1989.