FLUORESCENCE-SPECTRA OF POLYBENZAMIDE IN ISOTROPIC AND NEMATIC SOLUTIONS

The fluorescence spectra of polybenzamide (PBA) in N,N-dimethylacetami de with 3% LiCl (A) and in 98% H2SO4 (B) solutions have been studied b oth in very dilute and in nematic solutions. Stacked chromophores of P BA play an important role in the formation of nematic phase. Fluoresce nce intensity from solution A is much higher than that from solution B under the same conditions of excitation. Differences in the fluoresce nce behavior of solutions A and B are discussed in regard of the monoc hromophore emission and monochromophore excitation and long wavelength emission. Fluorescence emission has been shown to be an extremely sen sitive tool to probe some molecular species present in minute amounts, which show up readily in the excitation spectrum of fluorescence emis sion but escape from detection in the absorption spectrum.