Spectromicroscopy of C(60) and azafullerene C(59)N: Identifying surface adsorbed water

C(60) fullerene crystals may serve as important catalysts for interstellar organic chemistry. To explore this possibility, the electronic structures of free-standing powders of C(60) and (C(59)N)(2) azafullerenes are characterized using X-ray microscopy with near-edge X-ray adsorption fine structure (NEXAFS) spectroscopy, closely coupled with density functional theory (DFT) calculations. This is supported with X-ray photoelectron spectroscopy (XPS) measurements and associated core-level shift DFT calculations. We compare the oxygen 1s spectra from oxygen impurities in C(60) and C(59)N, and calculate a range of possible oxidized and hydroxylated structures and associated formation barriers. These results allow us to propose a model for the oxygen present in these samples, notably the importance of water surface adsorption and possible ice formation. Water adsorption on C(60) crystal surfaces may prove important for astrobiological studies of interstellar amino acid formation.