NEW ASSIGNMENT OF CRYSTALLINE AND ION-IRRADIATED GRAPHITE PHONON-SPECTRA

A comparison was made between the Raman spectra of virgin and ion-irra diated highly oriented pyrolytic graphite, relating them with their in frared spectre. Structural modifications, after ion beam irradiation a t moderate ion fluences (0.2 eV per carbon atom, average deposited ene rgy), were detected and a careful vibrational analysis was made in the light of the correlation between site and factor group symmetries of the graphite infinite crystal. This allows a new proposal for the assi gnment for the so-called G and D lines of the Raman phonon spectre. In teraction effects, of the type projectile-target, are envisaged to exp lain spectroscopic modifications of ion-irradiated graphite.