Determination of the K–Ar interaction potential in the XΣ and AΠ state from laser spectroscopic data

Abstract

The absorption spectrum of the van der Waals molecule KAr has been recorded between 12 870 and 13 040 cm−1 by means of high-resolution laser excitation spectroscopy in a supersonic jet expansion. About 1600 molecular absorption lines could successfully be assigned to the rovibrational structure of the electronic transition A 2Π←X 2Σ+ of 39KAr. In addition, a few absorption lines due to the isotopomer 41KAr have been detected. Spectroscopic parameters have been obtained for vibrational levels 0...3 of X 2Σ+ and 6...11 of A 2Π. Additional experimental information was provided by observing the spectral distribution of the fluorescence. The interatomic potentials of the X 2Σ+ and the A 2Π states have been derived from the experimental data by means of a fully quantum-mechanical approach using suitable analytical functions. Our final results for equilibrium distance Re and well-depth De are 5.404(5) Å and 40.1(6) cm−1 for X 2Σ+, 3.37(3) Å and 405(15) cm−1 for A 2Π1/2, and 3.34(3) Å and 427(15) cm−1 for A 2Π3/2. In addition, we could deduce qualitative information on the B 2Σ+ interaction potential from our experimental data yielding Re=7.10 Å and De=23 cm−1 as preliminary values.

Potential energy curves and spin-orbit coupling of light alkali-heavy rare gas molecules

“…This observation is consistent with the series of experiments performed on MAr, 8,15 which shows a clear decrease of the SO molecular effect as the mass of the alkali increases. We interpret this effect as another manifestation of the hybridization.…”

“…Experimentally, very accurate rovibrational spectrum were recorded for LiHe, 6 LiNe, 7 LiAr, 8 NaNe, 9,10 NaAr, 11 NaKr, 12,13 NaXe, 14 and also KAr. 15 These measurements were used to extract potential energy curves for the X 2 state and the excited A 2 1 2 and A 2 3 2 states. From a theoretical point of view, numerous model calculation based on CPP approach have been performed.…”

“…From a theoretical point of view, numerous model calculation based on CPP approach have been performed. 15,16,[21][22][23] Correlated methods, either configuration interaction or coupled cluster, were used recently for molecules made of Li and light RG. 16,17 Previous theoretical studies of Li-RG reported a large anomalous molecular spin-orbit effect.…”

Laser-Spectroscopic Investigation of Higher Excited Electronic States of the KAr Molecule

“…, R e ( JЉ) with relative intensities of 1:3:3:1, as explained in detail in (4). JЉ is the quantum number of total angular momentum (excluding nuclear spin) in the X 2 ⌺ ϩ state and the well-known e/f notation has been used for assignment of parity.…”

“…1, which shows the interatomic potentials of the various electronic states of KAr. For the X and the A state, we used the interatomic potential deduced from the laserspectroscopic data of Bokelmann et al (4), whereas the result of a model potential calculation of Düren and Moritz (11) was taken for the higher excited electronic states.…”