Several types of experimental protocols can be used to extract different types of information regarding the dependence of NP surface reactivity on T NP , reactant pressure, and time, including stepped or continuous T NP ramps, pressure ramps at constant T NP , and long-term reactivity measurements at constant T NP and pressure. In addition, pulsed heating experiments can be used to measure kinetics (or emission spectra) under conditions where mass change would be too rapid to follow by other protocols. Fig. shows results from a T NP -ramp experiment measuring sublimation for a hafnium NP with initial mass near 276 MDa, i.e., with ~1.546 million atoms. If spherical, this NP would have ~40.7 nm diameter, which is large enough that it should have bulk-like density and electronic and geometric structures, apart from a larger density of low-coordination surface sites than would be present on a flat single crystal surface. Fig. shows the raw M and T NP values vs. time, with an inset showing M vs. time on an expanded scale for the final ~10 minutes of the experiment. Fig. plots the T NP dependence of the mass loss rate in Arrhenius format (log rate vs. 1/T NP ), with T NP given on the top axis.