LASER-INDUCED FLUORESCENCE OF MATRIX-ISOLATED C4N2+

C4N2+ (N=C-C=C-C=N+) is produced in a self-igniting dc discharge from the neutral precursor seeded in neon and matrix-isolated at 5.5 K. From Fourier-transform absorption, laser excitation and emission spectra of the cation's A2PI(g) <-- --> X2PI(u) transition the three symmetric SIGMA(g) vibrational modes were obtained for both states involved and are compared with the corresponding ps-phase values. Additional emission bands are assigned to combination and overtone bands involving the asymmetric stretches and two bending vibrations of the ground state. Subsidiary emission/ absorption bands are interpreted as the forbidden DELTAOMEGA = +/- 1 transitions which become allowed due to perturbations by the surrounding matrix.