Knowledge Bank

Dichlorocarbone $(CC12)$ has been produced in a continuous supersonic free jet by pyrolysis of $(CH3)3SICCl2$ seeded in argon using a nozzie heated to $400\circ$C. Laser excitation spectra of several bands of the $A1B1\leftarrow X1A1$ electronic system have been obtained for the cold carbone $(\approxeq 20\circ K)$ in the 500-540 nm spectral region. Partial rotational resolution of several $(\nu 1,\nu 2,O)\leftarrow (0,0,0)$ progressions has yielded an assignment based on a perpendicular-band of a near-prolate symmetric rotor with clearly assignable band-head structure. Analysis of the band-head positions in conjunction with spectral band shape simulations leads to rotational constant information for the ground vibronic state and the various observed vibrational states of the $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}B1$ excited electronic state. Although the data are not complete, they provide reliable inferences to be made about the ground and excited electronic state structures.