LAUSR

A single nanoparticle (NP) mass spectrometry method was used to measure sublimation rates as a function of nanoparticle temper-ature (TNP) for sets of individual graphite and graphene NPs. Initially, the NP sublimation rates were ~400 times faster than that for bulk graphite, and there were large NP-to-NP variations. Over time, the rates slowed substantially, though remaining well above the bulk rate. The initial activation energies (Ea values) were correspondingly low and doubled as a few monolayer's worth of material were sublimed from the surfaces. The high initial rates and low Ea values are attributed to large numbers of edge, de-fect, and other low coordination sites on the NP surfaces, and the changes are attributed to atomic-scale "smoothing" of the sur-face by preferential sublimation of the less stable sites. The emissivity of the NPs also changed after heating, most frequently in-creasing. The emissivity and sublimation rates were anti-correlated, leading to the conclusion that high densities of low-coordination sites on the NP surfaces enhances sublimation but suppresses emissivity.