Laser-excited fluorescence spectra of lanthanum monoxide

Abstract

Abstract. 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 Σ + (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 Σ + (v = 1 to 5). Under our experimental conditions, bands of the ∆v = 0 sequence of the B→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.

S-type Stars: LaO Line List for the B2Σ+–X2Σ+ Band System

“…Dunningʼs aug-cc-pVQZ correlation-consistent basis set (Dunning 1989;Kendall et al 1992) has been adopted for the oxygen atom. The term energy values, T e , for the ¢ A and B states are calculated to be 8189 and 18,121 cm −1 , respectively, in agreement with the corresponding experimental values of 7844.1 (Bernard & Vergès 2000) and 17,878.7 cm −1 (Bernard et al 1999). The calculations have been carried out at a set of internuclear distances, R, ranging from 1.6 to 2.5 Å, by steps of 0.05 Å, and the resulting TDM curve has been interpolated by B-splines to create a set of 1592 points on the same R range.…”

“…Törring et al (1988) have obtained a precise set of rotational constants for v = 0-2 of the X 2 Σ + state by microwave spectroscopy. B v and D v for the X 2 Σ + state vibrational levels up to v = 5 were calculated using Equations ( 6) and (7), and were fixed for the X 2 Σ + state (Table 1): Bernard et al (1999) obtained equilibrium spectroscopic constants for both X 2 Σ + and B 2 Σ + states. We used the equilibrium constants from Bernard et al (1999) to calculate the starting values for the origins of the X 2 Σ + and B 2 Σ + vibrational levels for v = 0 to v = 5.…”

“…B v and D v for the X 2 Σ + state vibrational levels up to v = 5 were calculated using Equations ( 6) and (7), and were fixed for the X 2 Σ + state (Table 1): Bernard et al (1999) obtained equilibrium spectroscopic constants for both X 2 Σ + and B 2 Σ + states. We used the equilibrium constants from Bernard et al (1999) to calculate the starting values for the origins of the X 2 Σ + and B 2 Σ + vibrational levels for v = 0 to v = 5. The initial values of B v , D v , and γ v for the B 2 Σ + state were also calculated from the spectroscopic constants given in Bernard et al (1999).…”

“…LaO has four low-lying electronic states: X 2 Σ + , ¢ D A 2 , A 2 Π, and B 2 Σ + . The green B 2 Σ + -X 2 Σ + transition and the very red A 2 Π-X 2 Σ + transition have been studied many times (Bacis et al 1973;Bernard & Sibaï 1980;Bernard et al 1999) and the A 2 Π-A ¢ D 2 emission bands can be seen near 2 μm in the near-infrared (Bernard & Vergès 2000). The rotational lines of the A-X and B-X electronic transitions are doubled with a splitting of about 0.5 cm −1 .…”

3D Magneto-Optical Trap of Yttrium Monoxide

“…In conclusion, we demonstrate the three dimensional magneto-optical trapping of YO. To our knowledge, this represents the first MOT of a non-fluoride molecule, broadening the horizon of chemical diversity of cooled molecules to include oxides, which are of chemical [35], atmospheric, and astrophysical [36] relevance. It also represents the first MOT for a molecule with an electronic state intermediate to the main cycling transition states, which necessitates careful consideration of repump choice in order to rapidly cycle photons wihout losing molecules to dark states.…”