15min:

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

On our SiCN/SiNC experiment, we measured laser induced fluorescence excitation spectrum in the range, 27,500 33,000 cm^-1, under jet cooled condition. Some of the vibronic bands in the spectrum have been assigned to Si containing species, such as Si₂, SiCH₂, SiCN, and SiNC, but some remain unassigned. The strongest band among them has a ² -- ² type rotational structure. The rotational constants of the ground and excited states are determined to be about 0.11 cm^-1, and they are about half of those of SiCN and SiNC. The spin-orbit interaction constant is determined to be 141.7 and 2.7 cm^-1 for the ground and excited states, respectively. Those are comparable with 140.8 and 4.9 cm^-1 for the X ² and A ² states of SiCN (~not SiNC~), respectively. As a result of some discussion, we have finally conclude that the spectrum can be attributed to the ² -- X ² transition of Si--N--Si. The ^{2 +} -- X ² transition of Si₂N was studied by two groups. The rotational constant of the ground X ² state agrees with that of the previous work. The vibronic structure of the laser induced fluorescence excitation spectrum is unusual; the ² -- ² type vibronic bands have been only identified.