15min:

SHUNJI KASAHARA, KUMI AKITA AND MICHIRU YAMAWAKI, Molecular Photoscience Research Center, Kobe University, Nada-ku, Kobe 657-8501, Japan; MASAAKI BABA, Graduate School of Science, Kyoto University, Sakyou-ku, Kyoto 606-8502, Japan.

Several Doppler-free spectroscopic technique were applied to measure the rotational resolved high-resolution absorption and excitation spectra of the S₁ ¹B_1u S₀ ¹A_g electronic transition. Sub-Doppler excitation spectra and the Zeeman effects of the 0-0 and several vibronic bands up to the excess energy around 2410 cm^-1 were measured by crossing a laser beam perpendicular to a collimated molecular beam, and the Doppler-free absorption spectra of the bands of excess energy 435 cm^-1 and 1423 cm^-1 were also measured by Doppler-free laser polarization labeling spectroscopy at room temperature. The molecular constants of the observed several vibrational states of the S₁ ¹B_1u(v') and S₀ ¹A_g(v=0) state were determined. The local energy shifts were found in the bands higher than 1423 cm^-1 band, and identified as originating from the Colliolis interaction with other vibrational levels. The Zeeman splittings were found for all observed bands. The J, K-dependences of the observed splittings were studied. As a result, the observed Zeeman effects could be explained to be originating from the magnetic moment of the S₁ ¹B_1u state induced by mixing with S₂ ¹B_3u state by J-L coupling.