Confocal Raman spectroscopy from the surface of a polymer melt is shown to produce anomalous results for polarized Raman scattering of specific molecular vibrations. Values of the depolarization ratio that cannot exist in normal liquids are interpreted as due to surface-induced molecular orientation of the polymer chains. The technique provides one of the few direct experimental evidences of molecular-orientation effects predicted in lattice models of polymer melts. © 2001 The American Physical Society.
|Physical Review B - Condensed Matter and Materials Physics
|Published - Jan 1 2001