Electronic absorptions of C₅⁺ detected in the visible through action spectroscopy in a cryogenic trap

The 2?g?X2?u+ electronic spectrum of C5+ in the gas-phase with origin band at 513nm is reported following experiments a cryogenic ion trapping instrument. Buffer gas-cooled ions, generated by laser vaporisation graphite, were investigated using two action spectroscopy approaches. Laser-induced dissociation weakly bound C5+?Hen complexes synthesised trap reveal linear dependence absorption energies on n allowing prediction those bare C5+. These results are confirmed colour C5+, monitoring fragmentation into C3++C2 product channel. data supplemented high-level structure calculations which support assignment D?h symmetry to ground state. laboratory provide requisite needed for spectroscopic detection this terrestrial and extraterrestrial environments.