Laser-induced fluorescence of matrix-isolated C6N2+ and of C8N2+

Cyanopolyacetylene cations of the type NC-(CC)n-CN+ are produced in a self-igniting do discharge through HC3N/neon mixtures and isolated in solid neon. Fourier transform emission and laser excitation spectra of the A2∏u-X2∏g transition of the n = 2 (C6N2+) cation are recorded. Their analysis yields the symmetric stretching vibrations of the cation both in the ground state and in the excited A 2∏u state. The A2∏g-X2∏u transition of the n = 3 (C8N2+) cation is identified with the help of a simple one-dimensional particle in a box model. The Fourier transform emission of this transition is also recorded and analyzed.