EMISSION-SPECTRUM OF MASS-SELECTED C-4(-)C-2-PI(U)-]X(2)PI(G) IN A NEON MATRIX

The laser excited emission spectrum of the C-2 Pi(u) --> X(2) Pi(g) el ectronic transition of mass-selected C-4(-) embedded in a 5 K neon mat rix has been observed. This is an extension of the technique coupling mass spectrometry and matrix isolation and allows information on the v ibrational frequencies of the species in the ground state to be obtain ed. In the case of C-4(-), three vibrational frequencies (nu(1)(sigma( g)(+)) = 2047(20), nu(2)(sigma(g)(+)) = 936(20) and nu(4)(pi(g)) = 396 (20) cm(-1)) have been inferred for the X(2) Pi(g) state.