15min:

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

We have generated MgNC in supersonic free jet expansions, and measured the laser induced fluorescence excitation spectra of the vibronic bands of the A ² - X ^{2 +} transition. We have found some new features in the spectra, though part of the spectra were already reported by Wright and Miller. The new features are consisting of the ₂ bending vibronic bands. From the rotational analyses of some of the vibronic bands, we have obtained information on the vibronic structure of the A ² state of MgNC. The assignments of the ₂ vibronic bands were carried out utilizing the vibrational analyses of the dispersed fluorescence spectra obtained by the excitation of the ₂ vibronic bands. On the basis of the vibrational structures of the dispersed fluorescence spectra which are not only those of the ₂ vibronic bands but also the spectra obtained by the excitation of the other vibronic bands reported by us, the vibronic structure of the X ^{2 +} state of MgNC has been analysed. The vibronic structures of the A ² and X ^{2 +} states of MgNC will be discussed comparing with the computational results by Hirano group\footnoteT.~E.~Odaka, T.~Taketsugu, T.~Hirano and U.~Nagashima, J.~Chem.~Phys. ~\underline\textbf115, 1349 (2001); T.~E.~Odaka, T.~Hirano and P.~Jansen, J.~Mol.~Spectrosc. ~\underline\textbf211, 147 (2002); T.~Hirano, K.~Ishii T.~E.~Odaka and P.~Jansen, J.~Mol.~Spectrosc. ~\underline\textbf215, 42 (2002); T.~E.~Odaka, T.~Hirano and P.~Jansen, J.~Mol.~Spectrosc. ~\underline\textbf216, 379 (2002)..