As the NP was first heated, a non-zero Rbase was observed between 1400 and 1700 K (Fig. ), attributed to etching reactions with background gasses. In the 1800 -2000 K range, Rbase increased rapidly, due to increasing rates for sublimation, with Rsublimation values similar to those previously observed for graphitic NPs. During the 2 nd ramp, Rbase was zero up to 1700 K, indicating that the NP had already become inert to etching, but the rapid onset of mass loss at 1800 K showed that sublimation was still fast at high TNP. Rsublimation at 2000 K during the 2 nd ramp was only ~36% slower than in the 1 st . The results show that the NP evolved drastically during the 1 st ramp as ~3 MDa (~2 ML) sublimed.