Electronic spectra of long odd-number carbon chains C17–C21 and C13−–C21−

Electronic transitions of the odd-number neutral and anionic carbon chains C2n+1 (n=8–10) and C2n+1− (n=6–10) have been observed in a neon matrix at 6 K after co-deposition with laser-vaporized graphite. The assignments are based on a comparison with the previously identified electronic transition of C7 to C15 and C5− to C11−, and the monotonic wavelength dependence of the origin band on the number of carbon atoms. The 1Σ+u←X 1Σ+g transition of C17 to C21 appears between 455 and 544 nm. The A 2Π←X 2Π transition of C13− to C21− falls in the 1052–1675 nm region.