Our experimental protocols for single NP kinetics measurements have been reported previously along with the method for TNP determination, and analysis of the uncertainties in NP mass and reaction rates (~1.3% absolute, ~0.2% relative) and TNP (~6.2% absolute, ~2% relative). Further details are given in the SI. Briefly, a single carbon NP is trapped in a 3D quadrupole and laser heated above 1000 K, allowing the NP mass (M) and charge (Q) to be monitored over time, with temperature (TNP) determined from the NP emission spectrum (Fig. ). Monitoring M vs. time for an NP held in argon buffer gas (2 mTorr) allows the baseline mass loss rate (Rbase) to be measured. For TNP ≥ 1600 K, Rbase is dominated by sublimation (Rsublimation), but at lower TNP there can be noticeable mass loss from reactions with background gasses (e.g. O2, H2O) in the vacuum system. To measure oxidation kinetics, a partial pressure of O2 (PO2) is added to the argon, resulting in a new mass loss rate, which is converted to the oxidative etching rate (Roxid) by subtracting Rbase measured before and after each oxidation period. To allow comparisons between different size NPs, Rbase, Rsublimation, and Roxid are expressed in terms of Da/sec/nm 2 , i.e., the mass loss rates are normalized to nominal NP surface areas, which are calculated from the NP mass assuming spherical shape and the bulk density of the NP material. In most cases, the Roxid values are further converted to etching efficiencies (EEO2), i.e., the mass loss per O2 collision (Da/O2 collision), using collision rates calculated from PO2 and the nominal NP surface area. Because the nominal surface areas are lower limits on the true surface areas, the rates and EEO2 values are upper limits.