Optical spectroscopy of the surface of nanoporous diamond films

We have studied the IR absorption spectra of samples of porous ultrananocrystalline diamond (UNC diamond) obtained by selective etching of the sp ² phase in UNC diamond films. We show that the surface of porous UNC diamond is polyfunctional. We have studied the behavior of surface hydride, carbonyl, carboxyl, and hydroxyl groups as a function of annealing temperature in air and the time kept under normal conditions for UNC diamond films previously oxidized at 430°C–450°C. In the range from a few minutes to a few months, we studied the kinetics for establishment of the steady state for the functional adsorbed layer on the diamond surface under normal conditions. The observed growth in the intensity of the transmission bands due to hydride (CH _x ) and other hydrogen-containing functional groups is explained by dissociation of water molecules on the surface of the UNC diamond films.