Electronic absorption spectra of linear and cyclic Cn+n=7–9 in a neon matrix

The C(n)(+) n=7-9 cations were produced by electron-impact ionization of perchloronaphthalene, mass selected, and their electronic absorption spectra in 6 K neon matrices recorded. The linear and cyclic isomers of C7(+) and C8(+) are detected. Three systems of linear C7(+) are observed with origin bands near 770, 332, and 309 nm. The cyclic C7(+) shows two transitions near 676 and 448 nm. One system of linear C9(+) is observed commencing at 371 nm. Linear C8(+) shows five dipole-allowed electronic transitions from the X 2pi(g) ground state, and the strongest ones have the origin bands at 890.8 and 308.1 nm. Five electronic transitions of cyclic C8(+) are also discernible.