PLASMON DISPERSION MEASUREMENTS IN THE ELECTRON-MICROSCOPE - APPLICATION TO CARBON SOLIDS

The plasmon dispersion behaviour of several forms of disordered carbon , including glassy carbon, amorphous carbon, C-60 and tetrahedral amor phous carbon, has been investigated; the data are presented in the for m of maps. Differences in bonding structure are reflected in changes i n the plasmon dispersion behaviour. A simple model of the dispersion r elation in which variation in the plasmon frequency is dependent on th e momentum transfer to the power r shows that r decreases from 1.5 for glassy carbon to 0.6 for tetrahedral amorphous carbon. These variatio ns in r are interpreted in terms of changes in the electronic structur e for the material. (C) 1998 Elsevier Science Ltd. All rights reserved .