Theoretical investigation on photoionization from Rydberg states of lithium, sodium and potassium

Aymar, M; Luc‐Koenig, E.; Farnoux, F. Combet

doi:10.1088/0022-3700/9/8/013

Cited by 124 publications

(76 citation statements)

References 24 publications

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“…For p-levels we took ionization cross-sections published by Aymar et al (1976). For 2S, 2D, 2F levels the cross-sections calculated with the help of quantum defect method (Hofsaess 1979) were used.…”

Section: Potassiummentioning

confidence: 99%

Non-LTE abundances of Mg and K in extremely metal-poor stars and the evolution of [O/Mg], [Na/Mg], [Al/Mg], and [K/Mg] in the Milky Way

Andrievsky¹,

Spite²,

Коротин³

et al. 2010

A&A

123

126

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Aims. LTE abundances of light elements in extremely metal-poor (EMP) stars have been previously derived from high quality spectra. New derivations, free from the NLTE effects, will better constrain the models of the Galactic chemical evolution and the yields of the very first supernovae. Methods. The NLTE profiles of the magnesium and potassium lines have been computed in a sample of 53 extremely metal-poor stars with a modified version of the program MULTI and adjusted to the observed lines in order to derive the abundances of these elements. Results. The NLTE corrections for magnesium and potassium are in good agreement with the works found in the literature. The abundances are slightly changed, reaching a better precision: the scatter around the mean of the abundance ratios has decreased. Magnesium may be used with confidence as reference element. Together with previously determined NLTE abundances of sodium and aluminum, the new ratios are displayed, for comparison, along the theoretical trends proposed by some models of the chemical evolution of the Galaxy, using different models of supernovae.

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Section: Potassiummentioning

confidence: 99%

Non-LTE abundances of Mg and K in extremely metal-poor stars and the evolution of [O/Mg], [Na/Mg], [Al/Mg], and [K/Mg] in the Milky Way

Andrievsky¹,

Spite²,

Коротин³

et al. 2010

A&A

123

126

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“…As a result an expression for the product V c n (r) ⊗ P n (r) was obtained [4]. To have the possibility to compare our core polarization potential with the potentials used in earlier work [5,6,8,10,11] we construct the local form of this potential V CP n (r) by simply dividing the product V c n (r) ⊗ P n (r) by the AO P n (r):…”

Section: Atomic Orbitalsmentioning

confidence: 99%

“…In a recent paper, we have described a novel approach to include in these calculations the polarization of the core electrons by the outer valence electron in a realistic and efficient way [4]. For ground state alkali atoms, these core polarization effects have been known to be important for some time [5][6][7][8][9][10][11][12]. For outer electrons with less corepenetrating character it is expected that the effects of core a e-mail: hotop@physik.uni-kl.de polarization on near-threshold photoionization crosssections are less important.…”

Section: Introductionmentioning

confidence: 99%

Near threshold photoionization of excited alkali atoms Ak(np) (Ak = Na, K, Rb, Cs; n = 3-6)

Petrov

Sukhorukov

Leber

et al. 2000

The European Physical Journal D

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The effect of the polarization of the atomic core by the outer electron on near threshold photoionization of excited alkali atoms Ak(np) (Ak = Na-Cs; n = 3−6) is investigated. Partial and total cross-sections for photo-ionization of the np-electron were computed utilizing the configuration interaction technique with Pauli-Fock atomic orbitals (CIPF) and including the long range core polarization potential (CP). To calculate the core polarization potential the variational principle is applied. Comparison with previous theoretical results and with available experimental data is made for the total cross-section σ, for the electron angular distribution parameter β, for the ratio ν = |D d /Ds| of the reduced electric dipole matrix elements and for the phase shift difference ∆ = δ d − δs, associated with the d-wave and s-wave continua, respectively. In the comparison, new experimental results for σ, ν, and ∆, measured for laser-excited, polarized 39 K(4p 3/2 ) atoms, have been included.PACS. 32.80.Fb Photoionization of atoms and ions -33.60.-q Photoelectron spectra -31.50.+w Excited states

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“…With the laser power used, these electrons are mainly formed by Pennning ionization and photoionization processes. A calculation, for 8s level, using the Precival theory [24] gives an electron impact ionization cross section of 3×10 −14 cm 2 at an energy of 1.5 eV. Such a cross section provides ion density three orders of magnitude less than the total measured atomic ion density [1].…”

Section: The Dependence Of the Atomic Density Rb + On The Laser Powermentioning

confidence: 94%

Kinetics of Rb2+ and Rb+ formation in laser-excited rubidium vapor

Mahmoud

2008

Open Physics

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Abstract:We have studied the formation of the molecular ion Rb + 2 and the atomic ion Rb + . These are created in laser excited rubidium vapor at the first resonance, 5s-5p and 5p-nl transitions. A theoretical model is applied to this interaction to explain the time evolution and the laser-power dependence of the population density of Rb + and Rb + 2 . A set of rate equations which describe: the temporal variation of the population density of the excited states; the atomic ion density; and the electron density, were solved numerically under the experimental conditions of Barbier and Cheret [5]. In their experiment the Rb concentration was 1 × 10 13 cm −3 and the laser power was taken to be 50-500 mW at vapor temperature = 450 K. The results showed that the main processes for producing Rb + 2 are associative ionization and Hornbeck-Molnar ionization. The calculations have also showed that, the atomic ions Rb + are formed through the Penning Ionization (PI) and photoionization processes. Moreover, a reasonable agreement between the experimental results and our calculations for the ion currents of the Rb + and Rb + 2 is obtained. PACS (2008): 34.80. Dp, 34.50.Fa

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Theoretical investigation on photoionization from Rydberg states of lithium, sodium and potassium

Cited by 124 publications

References 24 publications

Non-LTE abundances of Mg and K in extremely metal-poor stars and the evolution of [O/Mg], [Na/Mg], [Al/Mg], and [K/Mg] in the Milky Way

Non-LTE abundances of Mg and K in extremely metal-poor stars and the evolution of [O/Mg], [Na/Mg], [Al/Mg], and [K/Mg] in the Milky Way

Near threshold photoionization of excited alkali atoms Ak(np) (Ak = Na, K, Rb, Cs; n = 3-6)

Kinetics of Rb2+ and Rb+ formation in laser-excited rubidium vapor

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