It remains a cage: ionization tolerance of C60 fullerene in planetary nebulae

Abstract

We demonstrate that by combining two robust theoretical quantum chemistry calculation techniques, stepwise ionization of C60 fullerene by UV and extreme UV photons can in principle occur up to a limit as high as C60(26+) before coulomb explosion of the cage. Furthermore, these highly ionized forms exhibit a comparable structural and bonding stability as for the neutral fullerene. Certain astrophysical sources like the central stars of planetary nebulae and the hottest white dwarf stars have sufficiently hard UV radiation fields that can result in a series of highly charged C60(q+) species from q=1 up to q=16. Harsher environments, like hot X-ray bubbles in planetary nebulae, X-ray binaries and other sources, may further push the ionization right up to the q=26 limit. These remarkable theoretical findings add new avenues to complex ion/molecule reactions the chemistry of fragmentation products and additional pathways for spreading carbon through-out the universe. The implications for the emerging field of astrochemistry of C60 fullerene in all its possible states could be profound.