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High-resolution spectroscopy and Ab initio calculations on HfCl

par Ram, Ram;Bernath, Peter ;Adam, Allan A.G.;Tsouli, Abdelaziz ;Liévin, Jacques
Référence Journal of Molecular Spectroscopy, 202, 1, page (116-130)
Publication Publié, 2000-07

Article révisé par les pairs

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Résumé :

The emission spectrum of HfCl has been investigated in the 3000-18 500 cm -1 region at high resolution using a Fourier transform spectrometer. The bands were excited in a microwave discharge through a flowing mixture of HfCl 4 and helium. Two bands near 17 140 and 17 490 cm -1 were also measured in absorption using laser excitation spectroscopy. In this instance the molecules were created by laser ablation in a molecular beam apparatus. The observed bands have been classified into two electronic transitions, [7.6] 4Δ 3/2-X 2Δ 3/2 and [17.1] 2Δ 3/2-X 2Δ 3/2 involving a common lower state. A rotational analysis of the 0-0 and 1-1 bands of [7.6] 4Δ 3/2-X 2Δ 3/2 and 0-0, 1-1, and 1-0 bands of the [17.1] 2Δ 3/2-X 2Δ 3/2 transitions has been carried out and the equilibrium spectroscopic constants have been determined. The ground state principal molecular constants are B e = 0.1097404(54) cm -1, α e = 0.0004101(54) cm -1, and r e = 2.290532(57) angstrom. Ab initio calculations have been performed on HfCl and spectroscopic properties of the low-lying electronic states have been predicted. The ground state is predicted to be a regular 2Δ state arising from the valence electron configuration, 1σ 22σ 23σ 21π 41δ 1. On the basis of our ab initio calculations, we assign the observed transitions as [7.6] 4Δ 3/2-X 2Δ 3/2 and [17.1] 2Δ 3/2-X 2Δ 3/2.