NPs transformed by brief CO2 laser pre-heating were the reactants in the etching and sublimation experiments, thus the changes caused by pre-heating are important in interpretation of the results. Bulk SiO2, in either crystalline or amorphous forms, has low absorptivity and emissivity across the visible and near-IR wavelength range, consistent with the observation (Fig. ) that initially trapped silica NPs irradiated at 532 nm (~100 W/cm 2 ) did not become hot enough to radiate measurable intensity in the <950 nm wavelength range. Brief exposure to a CO2 laser (~10 -50 W/cm 2 average intensity) irreversibly transformed the NPs such that 532 nm irradiation alone could heat the NPs to incandescence, emitting strong blackbody-like thermal spectra.