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Astron. Astrophys. Suppl. Ser. 139, 163-166

Laser-excited fluorescence spectra of lanthanum monoxide

The $B^2\Sigma^+{\rightarrow}X^2\Sigma^+$ system[*]

A. Bernard1 - F. Taher2 - A. Topouzkhanian3 - G. Wannous3

Send offprint request: A. Bernard

1 - CRAL-Observatoire de Lyon, 9 avenue Charles André, F-69561 Saint-Genis-Laval Cedex, France
2 - Groupe de Physique Moléculaire et Applications, CNRS Libanais, Beyrouth, Liban
3 - Laboratoire de Spectrométrie Ionique et Moléculaire (LASIM), CNRS et Université Claude Bernard-Lyon I, 43 Bd. du Onze Novembre 1918, F-69622 Villeurbanne Cedex, France

Received March 9; accepted May 26, 1999


Fluorescence spectra of lanthanum monoxide excited by selected Ar+ and Kr+ laser lines have been analysed by Fourier transform spectrometry. Rotational levels in the $B^2\Sigma^+(v=2, 3, 4)$ electronic state have been populated either directly or after collisional relaxation, inducing many fluorescence transitions to the ground state $X^2\Sigma^+(v=1$ to 5). Under our experimental conditions, bands of the $\Delta v=0$ sequence of the $B{\rightarrow}X$ system also appear, fairly developed.

A global treatment of the wavenumbers of some 830 lines in 9 bands of the system, involving the levels v'=0 to 4 and v''=0 to 5, is carried out. The consistent set of accurate effective spectroscopic constants for both electronic states, directly obtained at equilibrium, is expected to be useful for high resolution syntheses of S-type stellar spectra.

Key words: molecular data -- line: identification

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