Study of polymer film surfaces by EELS using selectively deuterated polystyrene

HREELS spectra of selectively deuterated polystyrene films show loss energies corresponding to the excitation of vibrational modes of the surface region of the organic medium. The thickness of the analyzed surface region can be varied by changing the incident electron energy and/or the scattering geometry. Selective labelling allows to better separate the contributions of main chain and of pendant-groups, and to eliminate the influence of contaminants. It is shown for instance that isotactic and atactic polymer surfaces differ, the former being mainly composed of phenyl rings. End group segregation at the surface may also be important. Multiple losses are much more intense than the corresponding combination modes in IR: the theory of interaction of low energy electrons with polymer films should be further investigated.