2008ApJ...677..348D

Electronic transitions of MgC_2n_ H (n=1-3) 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 A²Π⟵X²Σ⁺ electronic transition of linear chains. The origin bands are located at 4383, 4453, and 4525 Å for MgC₂H, MgC₄H, and MgC₆H, respectively, and provide a means of detecting such species in astronomical environments.