Diffuse reflectance infrared Fourier-transform study of the direct thermal fluorination of diamond powder surfaces

Abstract

The direct thermal interaction of elemental fluorine with (i) hydrogenated and (ii) oxidized diamond surfaces has been investigated by diffuse reflectance infrared fourier-transform (DRIFT) spectroscopy. The hydrogenated diamond surface is fluorinated by thermal reaction with elemental fluorine. Hydrogen chemisorbed on the diamond surface is abstracted by the reaction with fluorine molecules at –10 °C. Peaks due to C—F stretching vibrations are observed at 1098, 1251 and 1360 cm^–1 after the fluorination of the hydrogenated diamond. The oxidized diamond surfaces are affected by elemental fluorine. Peaks due to CO stretching vibrations on the oxidized diamond surfaces remained and shifted toward the higher wavenumber region as the temperature was decreased below 400 °C. The fluorination of the oxidized diamond at 500 °C gave similar chemisorbed states of fluorine compared with those of the hydrogenated diamond.