  Although fullerenes have long been hypothesized to occur in interstellar
environments, their actual unambiguous spectroscopic identification is of more
recent date. C60, C70 and C60+ now constitute the largest molecular species
individually identified in the interstellar medium (ISM). Fullerenes have
significant proton affinities and it was suggested that C60H+ is likely the
most abundant interstellar analogue of C60. We present here the first
laboratory infrared (IR) spectrum of gaseous C60H+. Symmetry breaking relative
to C60 produces an IR spectrum that is much richer than that of C60. The
experimental spectrum is used to benchmark theoretical spectra indicating that
the B3LYP density functional with the 6-311+G(d,p) basis set accurately
reproduces the spectrum. Comparison with IR emission spectra from two planetary
nebulae, SMP LMC56 and SMC16, that have been associated with high C60
abundances, indicate that C60H+ is a plausible contributor to their IR
emission.
