Oxidation of C60 fullerite by interstitial oxygen

Processes induced by the heating Of C-60 fullerite intercalated by oxygen are analyzed using mass-spectrometry, thermogravimetry, differential scanning calorimetry, and electronic spin resonance (ESR) techniques. It was found that the primary gas produced at the heating temperatures below 100 degrees C is molecular oxygen while at higher temperatures up to 200 degrees C carbon mono- and dioxides were also observed. The beating was accompanied by an appreciable increase in the ESR signal intensity. In order to gain insight into the oxidation products that are capable to contribute to the ESR signal, we performed all-electron density functional theory computations for C58On (n = 0-4), C59On, (n = 0-2), and endohedral complexes O-2@C-58, O-2@C-59, and O-2@C-60. It is found that the triplet states Of C-58, C58O3, O-2@C58O2, O-2@C-58, and O-2@C-60 are lower in total energy than the corresponding triplet states. The singlet and triplet states Of C-59, O-2@C-59, and C-60(2-) are nearly degenerate in total energy. Thus, there are a number of species that can be responsible for the paramagnetic behavior observed in the oxidized fullerene.