Nevertheless, the high-temperature region of the sample was significantly larger than the size of the molecular beam on the surface (1 mm high × 1.7 mm wide). The sample surface temperature where it was struck by the molecular beam was measured with the use of a Leeds-Northrup optical pyrometer. Optical pyrometers are calibrated for surfaces with emissivity, 𝜀𝜀 = 1, whereas the 𝜀𝜀 of carbon is ~0.8. The difference in computed flux using the observed temperature and estimated corrected temperature is small (see discussion in Supplementary Material). Furthermore, the exact emissivity of an oxidized FiberForm sample is unknown. Hence, we used the observed temperature in our analysis. Two experimental data sets were collected for scattering with the hyperthermal O/O2 beam.