ELECTRONIC SPECTRA OF MgC2nH (n = 1Y3) CHAINS IN THE GAS PHASE

Electronic transitions of MgC2nH (n = 1Y3) have been observed in the gas phase in the visible region. A mass-selective, resonant two-color two-photon ionization technique, coupled with a laser ablation source, was used. Ab initio calculations of the geometries, energies, and vertical electronic excitations have been carried out using hybrid density functional theory and the coupled-cluster approach. The spectra are assigned as the A 2 X 2+ electronic transition of linear chains. The origin bands are located at 4383, 4453, and 45258 forMgC2H,MgC4H, andMgC6H, respectively, and provide a means of detecting such species in astronomical environments