Potential curves of the rare gas alkali ions

Mantel, M.; Langhoff, H.

doi:10.1007/bf01437172

Cited by 4 publications

(1 citation statement)

References 8 publications

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“…This difference is ascribed to uncertainties in the potential curves of the upper state indicating that the calculated binding energies are too low by about 180meV (Table 3). Although in the opposite direction, the deviations are of the same magnitude as the results of a calculation using the pseudopotential method [ 13]. Improvements in the calculations were studied for (NeNa) +.…”

Section: Pacsmentioning

confidence: 89%

Ab-initio calculations of excited rare gas alkali ions

Markert

Das

Mantel

et al. 1994

Z Phys D - Atoms, Molecules and Clusters

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Abstract. The excimer-like ions formed by combining a rare gas ion with an alkali atom were investigated by an ab initio HF-CI calculation. The resulting four bound excited states 1S+, JII, 322+ and 3H were subjected to a semiempirical spin orbit (SO)-coupling yielding eight fine structure levels with angular momenta 12=2, 1 (3) and 0(4). For (NeLi) +, (NeNa) +, (ArLi) +, (arNa) ÷, (ARK) ÷ and (KrLi) ÷ the wavelengths for the five allowed transitions to the ground state were calculated. The results are in close agreement with the experimental results. Also other spectroscopic properties as binding energies, transition moments and vibrational quanta are given. PACS: 31.20.EjDiatomic ions Rg+A formed by combining a rare gas ion (Rg +) with an alkali atom (A) are of great interest, since they decay radiatively into the weakly bound ground state Rg A + formed by an alkali ion and a rare gas atom. In recent experimental investigations [1,2,3,4] it was shown that the ions decay by emission of radiation in the vacuum ultra violet region. Because of the weak bonding of the ground state these ions behave excimer-like and are potential candidates for lasers in the VUV.The observed transitions from the Rg+A ions with Rg = Ar, Kr or Xe and A = Li, Na, K, Rb, or Cs showed a fine structure [3]. In order to clarify its origin, in the present investigation the binding properties of some Rg + A ions were studied by ab-initio calculations.The binding of the Rg + A ions results from the polarizing action of the Rg + ion on the alkali atom. In most cases the asymptotic states Rg + (2P3/2, ZP1/2) + A (2S1/2) form the first excited states of the (Rg + A)* system. In a close vicinity the states Rg (3P0,1, 2, 1P1 )+ A (1S 0) + states are located. The resulting bound states of the molecular ions have 1'32; or 1'3H character leading to a total of eight fine structure levels with angular momenta of f2 = 2(1), 1(3), 0-(2) and 0+(2).Conceptually, the problem has been investigated in several steps. As a starting point serves a Hartree-Fock selfconsistent field (HF-SCF) method based on the assumption that each electron moves in an effective field provided by the nuclei and the whole electron distribution. An improvement to the energy due to non-dynamical correlation effects, which account for the degeneracy between different configurations and a rearrangement of electrons in partially filled shells, has been achieved by adding extra configurations to the HF reference state.

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Section: Pacsmentioning

confidence: 89%

Ab-initio calculations of excited rare gas alkali ions

Markert

Das

Mantel

et al. 1994

Z Phys D - Atoms, Molecules and Clusters

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Vacuum ultraviolet emission spectra of the helium and neon alkali ions in the range between 60–80 nm

Petkau

Hammer

Herre

et al. 1991

The Journal of Chemical Physics

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Mixtures of neon or helium with alkali vapor were excited using an argon ion beam. The emission continua observed in the vacuum ultraviolet region between 60 and 80 nm are assigned to the decay of the ionic excimers He+K, He+Na, He+Li, Ne+Rb, Ne+K, Ne+Na, and Ne+Li into the ground state consisting of a rare gas atom and an alkali ion. The binding energies of these excimers range between 0.46 and 0.85 eV. The obtained decay energies and the fine structure splittings agree with the predictions by calculations using phenomenological potentials and by ab initio calculations. Intense emission due to the inner shell excitation of K and Rb is also observed.

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Spectroscopy of ionic alkali rare gas excimers in matrices

Moeller¹,

Gürtler²

1997

The Journal of Chemical Physics

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Using a clean preparation technique of doping alkali atoms in argon matrices, VUV emissions of the charge-transfer states of the ionic xenon–alkali excimers (XeA)+ have been measured. With synchrotron radiation as an excitation source, the ionic species were generated in the matrix and energy and time-resolved spectroscopy has been performed with synchrotron radiation as an excitation source. The emissions of the charge-transfer reaction: (Xe+A)→(XeA+)+hν have been observed for all ionic (XeA)+ excimers with energies in the VUV range between 6.05 and 7.4 eV. The excitation spectra revealed a primary formation process through direct ionization of the xenon; however, neutral xenon resonance states are also contributing. As obtained from lifetime measurements, the bands are assigned to the 0I−→0+ transition of the fine-structure components which account for the long decay time. An increase of the xenon concentration favors the formation of ionic trimers (Xe2A)+ whose emissions have also been identified.

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Potential curves of the rare gas alkali ions

Abstract: The first excited states of the rare gas alkali ions have been calculated using Hellmanntype model potentials. The predicted decay energies agree with the results of a recent measurement within 2%.

Cited by 4 publications

References 8 publications

Ab-initio calculations of excited rare gas alkali ions

Ab-initio calculations of excited rare gas alkali ions

Vacuum ultraviolet emission spectra of the helium and neon alkali ions in the range between 60–80 nm

Spectroscopy of ionic alkali rare gas excimers in matrices

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