| DOPPLER-FREE TWO-PHOTON EXCITATION SPECTROSCOPY OF BENZENE IN A MOLECULAR BEAM (2008) | |||||||||
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| D. Y. Baek, J. Chen, J. Wang, A. Doi, S. Kasahara, M. Baba, and H. Kato, Bul. Chem. Soc. Jpn.H. Kato, M. Baba, and S. Kasahara, Bul. Chem. Soc. Jpn.. Author Institution: Molecular Photoscience Research Center, Kobe University, Kobe; 657-8501, Japan; Graduate School of Science, Kyoto University, Kyoto; 606-8502, Japan. The fluorescence quantum yield at the vibrational energy over 3000 cm$^{-1}$ in the $S_1 \;^1B_{2u}$ state of benzene is dramatically decreased. This phenomenon is called ''channel three'' and has been studied extensively. We have observed the ultrahigh-resolution spectrum of the $S_1 \leftarrow S_0 \;1^2_014^1_0$ band ($\;E_{\rm excess}$ = 3412 cm$^{-1}$) and found the Zeeman splitting which explained to be originating from the magnetic moment of the $S_1$ state induced by mixing with $S_2$ state by $J$-$L$ coupling. } ,{\bf 79}, 75 (2006).} }, {\bf 80}, 456 (2007).} In this work, we established the apparatus for the Doppler-free two-photon excitation (DFTPE) spectroscopy with a molecular beam and measured the $S_1 \leftarrow S_0 \;1^1_014^1_0$ and $1^2_014^1_0$ band of benzene. When we measured the DFTPE spectrum in a gas cell, many rotational lines were observed but the pressure broadening was remained. On the other hand, when we measured the DFTPE spectrum in a molecular beam, the influence of collision was decreased. The typical linewidth was 6 MHz. The high-resolution and collision-free condition is useful to investigate the perturbing region with high sensitivity and accuracy. | |||||||||
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