Laboratory measurement of the 1(01)-0(00) transition and electric dipole moment of SiC sub 2. [In interstellar space]

A laser-ablation source coupled to a pulsed-nozzle Fabry-Perot Fourier-transform microwave spectrometer is used to investigate the 1(01)-0(00) transition in (Si-28)C2, (Si-29)C2, and (Si-30)C2. The results are presented in tables, and the frequencies are found to be 23.600242(4), 23.257511(8), and 22.937583(8) GHz, respectively. From the electric dipole moment determined for (Si-28)C2, the SiC2 column density toward the evolved carbon star IRC + 10216 is estimated as 2.7 x 10 to the 14th/sq cm. This experimentally based value is shown to be about twice that calculated on the basis of theoretical dipole moments by Thaddeus et al. (1984). 12 refs.