Fig. shows that even after the diamond NP had become inert to O2, its sublimation rate was still substantial, and one obvious question is whether it might be possible to restore O2 reactivity by rapidly subliming material from the NP surface during a short period at high TNP. A test of this idea is shown in Fig. , which continues the time record from Fig. , when at the point just before the 2 nd oxidation period showing that the NP had already become O2 inert. The NP was then held in argon with one laser holding TNP = 1200 K, while a second laser (10 W, duty-factor modulated CO2 laser) was used to flash heat the NP for three short periods (solid TNP points). To avoid vaporizing the NP in the first flash, the CO2 laser power was increased between each flash until a large mass loss was observed. The SI gives details of the process used to estimate the TNP during each CO2 flash (Fig. ).