Reaction Probability and Infrared Detection of the Primary Ozonide in Collisions of O₃ with Surface-Bound C₆₀

The kinetics and mechanism of reactions between gas-phase ozone and surface-bound C60 have been investigated by monitoring changes to reflection–absorption infrared spectra within a well-characterized film of C60 during exposure to a controlled flux of pure ozone. These ultrahigh vacuum studies provide direct infrared spectroscopic evidence for the formation and decomposition of a primary ozonide of C60. The spectral assignments of this highly unstable intermediate have been verified using electronic structure calculations. Theory and experiment revealed that C60 oxidized nearly exclusively via addition of ozone across the double bond that links two six-carbon-containing rings of the molecule. Following spectral characterization, the initial probability for ozone to react with the surface was found to be 5.8 ± 0.2 × 10–4. Once formed, the ozonide quickly thermally decomposed to a variety of carbonyl-containing products.