RE15		10min5:34

TOKIO YUKIYA, NOBUO NISHIMIYA AND MASAO SUZUKI, Department of Electronic Engineering, Tokyo Institute of Polytechnics, Iiyama 1583, Atsugi City, 243-02 Kanagawa, Japan.

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The Doppler limited electronic absorption spectrum in the A ³_1u-- X ¹⁺_g system was measured in the 11650--12300 cm^-1 region using a Ti:sapphire ring laser (Coherent 899-21) pumped by an argon ion laser (Coherent Innova 90). The Q-branch lines of J =10 to 100 belonging to the v'<- v''= (29\!~\!31)'\!<-\!0'', (21\!~\!30)'\!<-\!1'' and (22\!~\!31)'\!<-\!2'' progressions were assigned. The hyperfine splittings of these lines could not be resolved. The wavelength measurements were done using a wavelength-meter (Anritu MF9630A) with an accuracy of \pm0.5 ppm. Using a least squares fitting procedure, the spectroscopic constants of _Q⁰, B_vf'-B_v'', D_vf'-D_v'' and H_v'-H_v'' were determined. The standard deviations were smaller than 0.003 cm^-1. By using the Dunham's coefficents of the X-state reported by Tromp and Le\,Roy\,( 1 \,), the spectroscopic constants of T'_v, B'_vf, D'_vf and H'_vf suitable for v'=21'~ 31' of the A-state were determined by a global least squares fits. The rotational constant of B'_vf at the v'=21 agreed with that reported by Ishikawa et al.\,( 2 \,) within the standard error, while the discrepancy of 0.1 cm^-1 was found at the value of T'_v.
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\makebox[0cm]\,( 1 \,) J.~W.~Tromp and R.~J.~Le\,Roy, J. Mol. Spectrosc. 109, 352--367(1985).
\makebox[0cm]\,( 2 \,) T.~Ishikawa, H.~Takekawa and K.~Obi, J. Mol. Spectrosc. 159, 443--457(1993).