The trap center was irradiated by a loosely focused 532 nm laser, and injection was stopped as soon as thermal emission was detected from a ~50 μm volume at the trap center. A charged NP oscillates in the trap with well-defined frequencies for radial and axial motion, proportional to Q/M, and we measure the axial frequency, Fz, by resonance excitation. The charge, Q, typically between +40e and +70e, was determined by fitting a series of steps in Fz caused by a series of single e -changes in Q, driven by a vacuum ultraviolet lamp. The absolute uncertainty in the extracted M values is estimated to be ±1.3%, mostly due to non-idealities in the trap, with relative uncertainties for comparing M measurements of ~±0.2%. TNP is determined simultaneous with M, by fitting 600 -1600 nm spectra emitted by the hot NP, using a thermal emission model consisting of Planck's law, times an empirical emissivity function, with absolute uncertainty estimated to be ~±6%. To measure kinetics, we simply measure M vs. time under reaction conditions, with absolute mass loss rates (Da/sec) determined by fitting linear regressions to the slopes of M vs. time. To extract the rates for N2O etching, the raw mass loss rates must be corrected for contributions from background reactions and sublimation. To allow correction for these processes, the baseline rate of mass loss, Rbaseline (= Rsublimation + Rbackground), was measured before (and usually)