ULTRAHIGH-RESOLUTION SPECTROSCOPY OF NAPHTHALENE $S_{1} \leftarrow S_{0}$ TRANSITION

Author Institution: Molecular Photoscience Research Center, Kobe University,; Nada-ku, Kobe 657-8501, Japan; Graduate School of Science, Kyoto University,; Sakyou-ku, Kyoto 606-8502, JapanSeveral Doppler-free spectroscopic technique were applied to measure the rotational resolved high-resolution absorption and excitation spectra of the $S_{1}$ $^1B_{1u} \leftarrow S_{0}$ $^1A_g$ electronic transition. Sub-Doppler excitation spectra and the Zeeman effects of the 0-0 }, {\bf 215}, 155 (2002).} 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$^{-1}$ }, {\bf 119}, 3691 (2003).} 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 $S_{1}$ $^1B_{1u}(v')$ and $S_{0}$ $^1A_g(v=0)$ 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 $S_{1}$ $^1B_{1u}$ state induced by mixing with $S_{2}$ $^1B_{3u}$ state by $J$-$L$ coupling. }, {\bf 122}, 144303 (2005).