DIRECT INTERACTION OF ELEMENTAL FLUORINE WITH DIAMOND SURFACES

Direct fluorinations of (i) hydrogenated diamond surfaces and (ii) oxi dized diamond surfaces have been performed by thermal reaction in elem ental fluorine. Chemisorption of fluorine on diamond powder surfaces h as been investigated by diffuse-reflectance infrared Fourier transform spectroscopy. The hydrogenated diamond surface is fluorinated by ther mal reaction in fluorine molecules. Hydrogen chemisorbed on the diamon d surface is abstracted by the reaction with fluorine molecules even a t -10 degrees C. Peaks due to C-F stretching vibrations are observed a t 1096, 1251 and 1347 cm(-1) after the fluorination of the hydrogenate d diamond at 100 degrees C. These C-F stretching peaks increase in int ensity with increase in fluorination temperature. C=O species on the o xidized diamond surface are affected by fluorine molecules above 100 d egrees C. Peaks due to C=O stretching vibrations on the oxidized diamo nd surface remained and shifted into the higher wavenumber region afte r reaction with fluorine at low temperatures below 400 degrees C. The fluorination of the oxidized diamond at 500 degrees C gives similar ch emisorbed states of fluorine to those of the hydrogenated diamond. The diamond surface is fully covered with fluorine by the fluorination at 500 degrees C.