Hydrogen bonding at grain surfaces and boundaries of nanodiamond films detected by high resolution electron energy loss spectroscopy

Abstract

Hydrogenated nanodiamond films consisting of 300 and 10-30 nm grain sizes were examined by high resolution electron energy loss spectroscopy. C-H stretching modes were identified at 350, 360, and 375 meV. The mode at 375 meV was enhanced in the case of 10-30 nm grain size and it is stable up to in situ annealing to >>800 degrees C. Complete hydrogen desorption occurs upon annealing to 1000 degrees C. Exposure of the nanodiamond film to atomic hydrogen results in a strong quenching of the 375 meV C-H mode, most likely due to preferential etching of (sp(2))-carbon-hydrogen at the surface and grain boundaries of the films.