POLARIZED VIBRATIONAL DENSITY OF STATES OF POLYANILINE FROM INCOHERENT NEUTRON-SCATTERING - MEASUREMENTS OF THE PHENYL-RING DYNAMICS

Incoherent inelastic-neutron-scattering data from stretch-aligned polyaniline (half-oxidized emeraldine base) films yield information on the polarized density of vibrational states in the 0-200-meV energy range. The spectra at low frequency are dominated by phenyl-ring librational dynamics; peaks that appear in the 7-10-meV range are assigned to this kind of motion, strongly supported by polarization analysis. These results should be pertinent to the problem of determining the nature of the ground and charge-defect states of polylaniline.