Matrix studies of the products of laser vaporization of graphite

Laser vaporization is shown to be an efficient source of ionic species for matrix studies. C₂⁻ and other ions are produced by vaporization of graphite. A new spectrum characterized by T_e = 19732 cm⁻, ω_e′ = 1507±2 cm⁻¹ and ω_e″ = 1360±5 cm⁻¹ is detected and assigned to C₂⁺ or, less probably, to C₃⁻. An efficient vibrational energy transfer between C₂ and C₂⁻ is observed.