Electronic absorption spectra of linear C6, C8 and cyclic C10, C12 in neon matrices

Abstract

The electronic absorption spectra of the even-numbered carbon molecules C6–C14 have been measured in neon matrices. Bare carbon anions were produced in a cesium sputter source, mass selected, codeposited with neon at 6 K, and neutralized. The spectra show, apart from the known (1) Σu−3←X 3Σg− transition of linear C6, C8, and C10 in the visible, absorption bands in the UV region. The spectral data when considered in conjunction with ab initio calculations show that the linear forms of C6 and C8 have the next strong (2) Σu−3←X 3Σg− transition with band maximum near 238 and 277 nm, respectively, whereas the band systems of C10, C12, and C14 at 316, 332, and 347 nm are due to the monocyclic species.