THE C3-PI(V'=0-6)-X3-PI(V''=0) TRANSITION IN SIC

We report the measurement of seven rovibronic bands belonging to the C3-PI-(v' = 0-6)-X3-PI-(v" = 0) transition in SiC. The molecules are produced by laser vaporization in combination with supersonic cooling and the transitions are detected using pulsed laser induced fluorescence spectroscopy. The vibrational and rotational structure of the C3-PI state are determined. Radiative lifetimes vary from 2886 ns for v' = 0 to 499 ns for v' = 6. Dispersed fluorescence spectra from the excited vibrational levels to the ground state have been measured and the vibrational constants of the electronic ground state were obtained. Both the v' dependence of the radiative lifetime and observed anomalous intensity distributions in the fluorescence spectra are explained by an electronic transition moment function that varies with the internuclear distance. The results are compared with ab initio calculations.