The effective rates obtained from the residual fits of TD-slow1 and TD-slow2 were used to compute apparent activation energies using an Arrhenius law, k = A𝑒𝑒 -𝐸𝐸/𝑘𝑘𝑘𝑘 . The energies obtained through these fits should not be considered as barriers for elementary processes. These are effective barriers arising from the competition of various processes occurring on the FiberForm surface. The Arrhenius fits for FiberForm and vitreous carbon are shown in Figures and respectively. The energies obtained for FiberForm are 32.2 kJ mol -1 and 59.6 kJ mol -1 for TD-slow1 and TD-slow2 respectively, while the energies predicted for vitreous carbon are much lower (TD-slow1 = 11.11 kJ mol -1 and TD-slow2 = 19.42 kJ mol -1 ). The effective rate constants in our fits contain two terms, k and [Cs], where [Cs] depends on surface coverage. As FiberForm is expected to have a higher coverage of O, [Cs] would be higher in the case of FiberForm. Therefore, the estimated energies from the fits are consistent with the expected trends. Inconsistencies were observed when the simultaneous fitting method was used to analyze the TOF distributions. The TD-prompt component of the CO flux continues to increase exponentially even at the highest temperatures (Figure , Supplementary Material) with this fitting procedure. Furthermore, the Arrhenius activation energy is higher for the faster decay process (TD-slow1), which is unrealistic (Figure , Supplementary Material). Analysis of TOF distributions of CO from vitreous carbon exhibited the same trends for the simultaneous fitting method. These two observations suggest that the residual fitting method is a more robust approach to fit the TOF distributions. Although the activation energies are different, the relative fluxes of thermal CO (TD-prompt, TD-slow1, TD-slow2) show similar trends for both FiberForm and vitreous carbon. This can be seen in Figure , where the flux percentages of the thermal components of CO are plotted. The similarities in TOF distributions and fluxes at various surface temperatures suggest that the chemical reactivities of FiberForm and vitreous carbon are similar.