Fig. examines the effects of time and TNP on the O2 reactivity of a single diamond NP. Prior to the start of the data record shown, the NP had been trapped and Q-stepped, but TNP was kept below 1200 K to minimize thermal effects on the NP prior to the oxidation measurements. TNP was then stepped from 1200 to 1600 K, dropped back to 1200 K, then stepped again to 1500 K. At each TNP, Rbase was measured before and after each oxidation period (cyan background, PO2 = 4.3 x 10 -5 Torr). Fig. plots the Rbase, Roxid, and EEO2 values for each TNP.