Charge-induced formation of thin conducting layers on fluorinated graphite surface

We show that irradiation of room-temperature fluorinated graphite of C2F composition by electron beam with a kinetic energy of 500 eV detaches the fluorine atoms from two or three top layers. The dielectric property of C2F prevents effective penetration of the beam in depth of the sample, and electrons are accumulated between the interior layers. Comparative study of the initial C2F sample and that after irradiation by means of X-ray photoelectron, X-ray absorption near edge structure, Raman and reflection optical spectroscopy detects a partial recovering of the π-bonds which increases the surface conductivity by more than three orders. The mechanism responsible for removal of fluorine atoms from dielectric matrix under electron irradiation is proposed and substantiated by quantum chemical calculations.