15min:
LASER INDUCED FLUORESCENCE SPECTROSCOPY OF JET COOLED SiCN : ROTATIONAL ANALYSIS OF THE HOT BANDS.

MASARU FUKUSHIMA AND TAKASHI ISHIWATA, Faculty of Information Sciences, Hiroshima City University, Asa-Minami, Hiroshima 731-3194, Japan.

We have generated SiCN in supersonic free jet expansions, and observed the laser induced fluorescence (~LIF~) of the vibrationally hot bands of the A 2 Delta -- X 2 Pi transition. We have measured dispersed fluorescence (~DF~) spectra from the single vibronic levels (~SVL's~), A (0110) 2 Phi and 2 Pi, and rotationally resolved LIF excitation spectra of the two hot bands, A (0110) 2 Phi -- X (0110) 2 Delta and A (0110) 2 Pi -- X (0110) 2 Sigma^(-). The rotational energy levels were reasonably analyzed as those of the 2K' -- 2K'' transitions, but their line intensities calculated from the Hönl-London factors derived in the intermediate case between Hund's case (a) and (b) could not reproduce the observed spectra. The Hönl-London factors derived in the 2 Lambda' -- 2 Lambda'' (~2 Delta -- 2 Pi~) transition reasonably reproduced the spectra. It indicates that coupling between the electronic orbital and vibrational angular momenta is weak in the SiCN 2 Delta -- 2 Pi system, and a basis set of | Lambda v2 l Sigma; J P MJ\rangle, so-called ''l-basis", better describes the system than that of | Lambda v2 K Sigma; J P MJ\rangle.