Electronic spectra of linear carbon anions Original Research Article

Resonance enhanced two colour photodetachment spectroscopy has been employed to probe several electronic transitions of mass selected anionic carbon chains in the gas phase. Spectra of the A 2Πg ← X 2Πu transition of C5−, A 2Πu ← X 2Πg and B 2Πu ← X 2Πg transitions of C7− and A 2Πg ←X 2Πu, B 2Πg ← X 2Πu and C 2Πg ← X 2Πu transitions of C9− were obtained, yielding origin bands significantly narrower than those reported previously. In addition, two (x) 2Πu ← X 2Πg (x = 2,3) electronic transitions of C4− with band origins at 25989 and 28717 cm−1have been detected. The improvements in the resolution and extended scan range of the spectra have enabled values for the gas to neon matrix shift for the vibronic bands to be inferred. Comparison of the observed transitions with the tabulated diffuse interstellar bands indicate that none of these are due to Cn− (n< 10).