Kinetics of C-NO and C-N2O reactions

Apparent turnover frequency (TOF) rates for the C-NO reaction were calculat ed on the basis of overall rates measured for three graphite samples with d ifferent dimensions at various temperatures (500-750 degreesC) and partial pressures. These TOF rates were rates per edge site on the edges of the cry stals. The TOF rates were also determined for one of these graphites for th e C-N2O reaction. Temperature breaks on the Arrhenius plots were observed f or the C-NO reaction while no such temperature break was observed in TOF ra tes measured by directly following the etch pit growth rates (using STM). T he temperature break phenomenon is attributed to pitting (and the ensuing p it growth) by O atoms dissociated from NO. The TOF rates appeared to be inv ersely proportional to the basal plane crystal size. This result was attrib uted to the steps and defects that also contributed significantly to the ov erall rates.