Classical and quantal studies of the satellite features in the absorption spectra of lithium(2s−2p)perturbed by helium

Abstract

This work reports a theoretical analysis of the Li͑2s → 2p͒ photoabsorption spectra when the lithium atoms are evolving in a ground helium buffer gas. The influence of temperature on the far-line wing spectra is particularly examined by adopting classical and full quantum-mechanical approaches. The computations show the appearance, above approximately 1000 K, of satellite structures in the blue wing around the wavelength 536 nm. The data obtained in the range of temperature 500-3000 K agree very well with those already calculated with different theoretical methods.

Ab initio potential energy curves and transition dipole moments for the interaction of a ground state He with Na(3s–3p)

“…The knowledge of the interaction energies between alkali-metal and helium atoms as well as of the dipole moments governing the transitions between the electronic states of the temporarily formed molecule MHe is required for the calculations of resonance line profiles of alkali atoms broadened by collisions with He atoms [1][2][3][4][5][6][7][8][9]. The accuracy of calculated spectral line profiles is strongly dependent on the accuracy of potential energy curves (PECs) and transition dipole moments (TDMs) for the system MHe under consideration.…”

Theoretical and laboratory spectra of sodium perturbed by molecular hydrogen

“…These satellite bands of alkali metals perturbed by rare gas have been extensively studied in the past (Allard & Kielkopf 1982, and references therein). There was a renewal of interest (Burrows & Volobuyev 2003;Allard et al 2003Allard et al , 2005Allard et al , 2007cAllard & Spiegelman 2006;Zhu et al 2005Zhu et al , 2006Alioua & Bouledroua 2006;Alioua et al 2008) because alkali-metals are a prominent source of opacity in the spectra of brown dwarfs (Allard et al 2003(Allard et al , 2007a. Blue satellite bands in alkali-He/H 2 profiles can be predicted from the extrema in the difference potentials ΔV(R), given by…”

Pressure-broadened atomic Li(2s-2p) line perturbed by ground neon atoms in the spectral wings and core

“…The computed linewidth and shift cross sections from Eqs. (10) and (11) are given respectively in Figs. 7 and 8, where the average curves are determined with Eq.…”

“…There are various recent theoretical studies of the alkali lines broadened by rare gases. These studies have employed semiclassical [5][6][7] and quantum [8][9][10][11][12][13][14] theories over a limited temperature domain. There are also some laboratory measurements of the broadened alkali lines in the wings.…”