Oxygen atoms are the most abundant surface intermediate across this regime (Supplementary Fig. ), and by degree of rate control 33 analysis (Supplementary Fig. ), N 2 dissociative adsorption is rate-controlling, both consistent with the high N 2 dissociation barrier. The green region of Fig. shows TOFs at N 2 and O 2 vibrational temperatures from 3000 to 10 000 K. TOFs are increased substantially relative to thermal-only catalysis, especially at the lowest bulk temperatures, and apparent activation energies are diminished. Predicted surface coverages are unchanged from the thermal case (Supplementary Fig. ) but the rate-controlling step changes to NO desorption at lower bulk and O 2 adsorption at higher bulk temperatures (Supplementary Fig. ), consistent with N 2 dissociation rates enhanced by vibrational excitation. The orange region of Fig. shows TOFs at N radical density artificially set to 2 to 8 orders of magnitude less than the N 2 density and O/O 2 fraction to 10N/N 2 . N and O radicals have a similar to even greater enhancing impact on NO TOFs, most notably at the lowest bulk temperatures. NO is the most-abundant surface species at bulk temperatures below 800 K (Supplementary Fig. ), and NO desorption becomes rate controlling (Supplementary Fig. ), both reflecting the assumed barrierless accommodation of O and N by the Pt surface. At higher bulk temperatures, surface coverages tend to zero and rates become controlled by oxygen adsorption. Both vibrational excitation and radical adsorption relax the rate limitations of N 2 dissociation and are particularly effective at lower bulk temperatures.