Double excitation in the K absorption spectrum of neon

Esteva, J.M.; Gauthé, B.; Dhez, P.; Karnatak, R.C.

doi:10.1088/0022-3700/16/9/003

Cited by 89 publications

(61 citation statements)

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“…The structure comprising the D 3 -D 5 features is virtually identical to the structure observed in the NEXAFS of gaseous Ne [11] except for a uniform shift of 1.8eV to higher energy. This structure in the gas phase has been attributed to 'P states arising from the ls'2s 2 2p53p 2 configuration, final states in the ls2p->3p3p excitation.…”

Section: Abstract (Maximum 200 Words)supporting

confidence: 57%

Two-center two-electron excitations identified in NEXAFS for solid Ne

1996

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REPORT DOCUMENTATION PAGEForm Aoved PIO( t O'l'ft l b..dtn tfo tlhsi cQIIeCOn 0 flIO rmatO,|o-estin*atro to a (verge I hour tponje• including the timc ot recviewing in t.uction. seta(Ching exq sinst gt dA a $Out(,, g14ther'*n O .14 antn~ n the data needed. And Cinplt elmtg and tev.€i *ng the QI1CCUen or i* .taon. S cnd (onment$ Aiedgdrnq this burden cisrt imt, 0 any other jS•p(t O0 th,.s collec'.o. of nIlor. At.On. nc:lud-mg S.ggetiOns 10, r ,educing this b cden. Experimental K-edge NEXAFS (near edge X-ray absorption fine structure) data for solid Ne are compared with theoretical results. Seven features in the experimental spectrum that are not reproduced by the theoretical results are found to be attributable to two-electron excitations. Five of them are usual one-center excitations, but the remaining two are found to be novel two-center excitations involving resonant orbitals as opposed to the usual bound orbitals. In contrast, twocenter, two-electron excitations involving only bound orbitals are found to be absent in the experimental spectrum.PACS numbers: 78.70.Dm, 32.30.Rj, 71.90.+qIn photo-absorption spectra, one-electron (l-e) excitations normally dominate the spectra for obvious reasons. Much weaker two-electron (2-e) shakeup excitations, nevertheless, have been observed in many atomic, molecular, and solid systems. In solids and molecules, these 2-e excitations can be either one-center ( Rehr and co-workers [6,7]. The input data for these calculations include the coordinates for 87 atoms (which form 6 shells with an fcc lattice constant of 4.463A [8]), the sample temperature (6.3K), the Debye temperature (66.0K) [9], and a choice for the self-energy as 3 described below. All other information, including the core lifetime, are internally provided by the code. We have performed full MS calculations incorporating the maximum number of paths that the code allows. In Ne solid, the inelastic mean free path of the photoelectrons is very long (>80,k) for electron energies less than 20eV but rapidly decreases to 20A above 30eV [10]. In order to include this large variation in the mean free path, we have performed two calculations, one without inelastic loss [theory (a)] and one with inelastic loss [theory (b)]. We employed the ground-state, exchange-correlation potential with a zero imaginary part for (a) and the complex Hedin-Lundquist self-energy for (b). Thus, the theoretical result (a) simulates the experimental spectrum below 30eV and (b), above 30eV. These sections of the spectra are indicated by solid lines in Fig. I and represent our theoretical spectrum.The sharpest peak (El) in the experimental solid Ne spectrum closely resembles the Is -+ 3 p excitation peak for gaseous Ne, so that peak E 1 has been attributed to the ls--*3pexciton [5]. The FEFF6 model is limited to an "extended" continuum spectrum above the Below we shall discuss the origins of those Di features.The structure comprising the D 3 -D 5 features is virtually identical to the structure observed in the NEXAFS of gaseous Ne [11] except for...

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Section: Abstract (Maximum 200 Words)supporting

confidence: 57%

Two-center two-electron excitations identified in NEXAFS for solid Ne

1996

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“…b The result obtained by Hitchcock & Brion (1980) has to be interpreted as an improved upper limit for the natural line width. c Esteva et al (1983). d Teodorescu et al (1993).…”

Section: Neutral Neon Atomsmentioning

confidence: 99%

“…The experimental data available in the literature were inferred from the analysis of spectra arising from K-vacancy levels of Ne excited by irradiation of neutral neon gas. Experimental widths inferred for the ( ) + s s p Ne 1 2 2 S 2 6 2 1 2 level are 0.23 ± 0.02 eV (Gelius 1974, this value was later corrected to 0.27 eV; Svensson et al 1976), 0.30 ± 0.04 eV (Esteva et al 1983), 0.21 eV (Teodorescu et al 1993, without an estimate of the uncertainty), and 0.25 ± 0.03 eV (Avaldi et al 1995). The present experiment yielded 0.261 ± 0.005 eV.…”

Section: Resonance Parameters and Decay Probabilitiesmentioning

confidence: 99%

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Photoionization of Ne Atoms and Ne⁺ Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

Müller

Bernhardt

Borovik

et al. 2017

ApJ

114

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Single, double, and triple photoionization of Ne + ions by single photons have been investigated at the synchrotron radiation source PETRA III in Hamburg, Germany. Absolute cross-sections were measured by employing the photon-ion merged-beams technique. Photon energies were between about 840 and 930 eV, covering the range from the lowest-energy resonances associated with the excitation of one single K-shell electron up to double excitations involving one K-and one L-shell electron, well beyond the K-shell ionization threshold. Also, photoionization of neutral Ne was investigated just below the K edge. The chosen photon energy bandwidths were between 32 and 500 meV, facilitating the determination of natural line widths. The uncertainty of the energy scale is estimated to be 0.2 eV. For comparison with existing theoretical calculations, astrophysically relevant photoabsorption cross-sections were inferred by summing the measured partial ionization channels. Discussion of the observed resonances in the different final ionization channels reveals the presence of complex Auger-decay mechanisms. The ejection of three electrons from the lowest K-shell-excited Ne + ( s s p 1 2 2 S 2 6 2 1 2 ) level, for example, requires cooperative interaction of at least four electrons.

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“…Of the noble gases, the natural candidates for such measurements, the E edges of neon [4], argon [5], and krypton [6 -8] were measured with high resolution, showing a rich spectrum of twoand three-electron excitations as well as important details of the underlying one-electron (le) spectra. These spectra, and in particular the Ar one, were used in a number of theoretical studies to test models for the excitation dynamics and the relative importance of effects such as postcollisional interaction, relaxation, and exchange [2, 9 -11].…”

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X-ray multielectronic photoexcitations near theKedge of xenon

Deutsch

Kizler

1992

Phys. Rev. A

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The near-K-edge x-ray photoabsorption spectrum of xenon was measured using synchrotron radiation.Several simultaneous two-electron excitation features were detected. Their identi6cation is supported by nonrelativistic and relativistic energy-level calculations. The relative cross sections extracted from the data are consistent with previous measurements on Kr. Relativistic sudden-approximation-shake-theory cross sections are found to overestimate the measured ones by factors of 2 -3, but closely follow leveldependent trends in the measured data.PACS number(s): 32.30. Rj, 32.80.Hd Simultaneous multielectronic excitations in an atom can provide, in principle, information on intershell and intrashell correlations [1,2]. A method of choice for probing these excitations are near-edge photoabsorption measurements, which yield direct energy-level and crosssection information, provided that monatomic gaseous samples are used. In solids, liquids, and even gases of

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Double excitation in the K absorption spectrum of neon

Cited by 89 publications

References 14 publications

Two-center two-electron excitations identified in NEXAFS for solid Ne

Two-center two-electron excitations identified in NEXAFS for solid Ne

Photoionization of Ne Atoms and Ne⁺ Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

X-ray multielectronic photoexcitations near theKedge of xenon

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Double excitation in the K absorption spectrum of neon

Cited by 89 publications

References 14 publications

Two-center two-electron excitations identified in NEXAFS for solid Ne

Two-center two-electron excitations identified in NEXAFS for solid Ne

Photoionization of Ne Atoms and Ne+ Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections

X-ray multielectronic photoexcitations near theKedge of xenon

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Photoionization of Ne Atoms and Ne⁺ Ions Near the K Edge: PrecisionSpectroscopy and Absolute Cross-sections