HIGH-RESOLUTION ELECTRON-ENERGY-LOSS SPECTROSCOPY OF THIN CRYSTALLINEHIGHLY ORIENTED FILMS OF POLY(TETRAFLUOROETHYLENE)

High-resolution electron energy loss spectroscopy (HREELS) spectra of highly oriented films of poly(tetrafluoroethylene) (PTFE) are reported . With one exception, all peaks in the spectra correspond to IR active vibrations. They are well resolved, and with a remarkably high intens ity, more than two orders of magnitude greater than we have observed o n any other polymer in HREELS. The angular distributions of the elasti c peak, and of the vibrational peaks are very narrow, which indicates both a well ordered system and a dipolar scattering behaviour. No evid ence of amorphous regions in these films is found. A Raman active mode can be observed in off-specular geometry, using an incident electron beam coplanar with the PTFE fibers direction. This corresponds to reso nance excitation of a transient negative ion state, with a maximum cro ss-section at an incident electron kinetic energy of about 4 eV.