The structure of nitrogenated carbon and its interaction with lubricant molecules

We report results for the structure of nitrogenated carbon and its interaction with lubricant molecules. The IR peak absorbance around 1600 cm^-1 is very pronounced and is representative of sp² bonding for the substituted graphite ring. The IR signal from sp bonding for nitrogen doping levels up to about 16% is found to correlate well with the nitrogen content in the samples prepared under various conditions. This good correlation indicates that the majority of N atoms in the C:N films contribute to the peak around 1600 cm^-1. This provides the evidence that substitutional graphite ring doping is the primary process of incorporating N into C at low levels of N doping. The planar benzene rings of lubricant molecules were found to orient themselves differently on nitrogenated carbon surfaces prepared under different conditions. This is attributed to the interaction between the graphite rings in the carbon surface layer and lubricant molecules