Direct interaction of elemental fluorine with diamond surfaces

Abstract

Direct fluorinations of (i) hydrogenated diamond surfaces and (ii) oxidized diamond surfaces have been performed by thermal reaction in elemental fluorine. Chemisorption of fluorine on diamond powder surfaces has been investigated by diffuse-reflectance infrared Fourier transform spectroscopy. The hydrogenated diamond surface is fluorinated by thermal reaction in fluorine molecules. Hydrogen chemisorbed on the diamond surface is abstracted by the reaction with fluorine molecules even at −10 °C. Peaks due to CF stretching vibrations are observed at 1096, 1251 and 1347 cm −1 after the fluorination of the hydrogenated diamond at 100 °C. These CF stretching peaks increase in intensity with increase in fluorination temperature. CO species on the oxidized diamond surface are affected by fluorine molecules above 100 °C. Peaks due to CO stretching vibrations on the oxidized diamond surface remained and shifted into the higher wavenumber region after reaction with fluorine at low temperatures below 400 °C. The fluorination of the oxidized diamond at 500 °C gives similar chemisorbed states of fluorine to those of the hydrogenated diamond. The diamond surface is fully covered with fluorine by the fluorination at 500 °C.