Thus, one question is whether oxidative etching promotes evolution to more stable/less reactive surface structure, or if similar evolution also occurred in the sublimation experiments, but was simply not detected because sublimation is less sensitive to surface structure than oxidation. Fig. shows three experiments testing this question for graphite, diamond, and nano-onion NPs. The experiments were identical to those in Figs. , with the exception that the NPs were held under inert conditions for most of the time, with O2 only added briefly to probe EEO2 at the beginning and end.