Kinetics of C-NO and C-N₂O reactions

Apparent turnover frequency (TOF) rates for the C-NO reaction were calculated on the basis of overall rates measured for three graphite samples with different dimensions at various temperatures (500-750°C) and partial pressures. These TOF rates were rates per edge site on the edges of the crystals. The TOF rates were also determined for one of these graphites for the C-N₂O reaction. Temperature breaks on the Arrhenius plots were observed for the C-NO reaction while no such temperature break was observed in TOF rates measured by directly following the etch pit growth rates (using STM). The temperature break phenomenon is attributed to pitting (and the ensuing pit growth) by O atoms dissociated from NO. The TOF rates appeared to be inversely proportional to the basal plane crystal size. This result was attributed to the steps and defects that also contributed significantly to the overall rates.