Suboxide interface in disproportionating<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>a</mml:mi></mml:math>-SiO studied by x-ray Raman scattering

Sakko, Arto; Sternemann, Christian; Sahle, Christoph J.; Sternemann, H.; Feroughi, Omid M.; Conrad, Heiko; Djurabekova, Flyura; Hohl, A.; Seidler, Gerald T.; Tolan, Metin; Hämäläinen, K.

doi:10.1103/physrevb.81.205317

Cited by 14 publications

(13 citation statements)

References 51 publications

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“…In Figure 6, the GOS results for the resonances in the LBH band, as measured by NIXS and EELS, are reported and compared to earlier EELS studies. Because earlier work reported the integrated GOS of the entire 9 eV spectral feature [19,[24][25]27], Our calculations strongly support this explanation as well, as can be seen in molecules and future studies with the same framework but using more sophisticated exchange-correlation functionals could also tackle e.g. double excitations.…”

Section: Resultssupporting

confidence: 82%

“…As with traditional x-ray absorption spectroscopies, NIXS results are most valuable in conjunction with appropriate theoretical treatment. This has been demonstrated in weakly correlated condensed phase systems with the use of multiple scattering [24][25][26] and density functional [27][28] techniques, and in strongly correlated systems with the application of atomic multiplet theory [3,29] and density functional methods [30]. New theoretical treatments of molecular systems at a reasonable computational cost are very valuable, and they can now be directly compared against the comprehensive interrogation of electronic structure provided by NIXS.…”

Section: Introductionmentioning

confidence: 99%

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Reexamining the Lyman-Birge-Hopfield band of N2

et al. 2011

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Motivated by fundamental molecular physics and by atmospheric and planetary sciences, the valence excitations of N 2 gas have seen several decades of intensive study, especially by electron energy loss spectroscopy (EELS). It was consequently surprising when a comparison of nonresonant inelastic x-ray scattering (NIXS) and nonresonant EELS found strong evidence for violations of the first Born approximation for EELS when leaving the dipole scattering limit. Here we reassess the relative strengths of the constituent resonances of the lowest energy excitations of N 2 , encompassed by the socalled Lyman-Birge-Hopfield (LBH) band, by expanding on the prior, qualitative, interpretation of the NIXS results for N 2 by both quantifying the GOS of the lowestenergy excitations and also presenting a new time-dependent density functional theory calculation of the q-dependence of the entire low-energy electronic excitation spectrum.At high q, we find that the LBH band has an unexpectedly large contribution from the octupolar w 1 Δ u resonance exactly in the regime where theory and EELS experiment for the presumed-dominant a 1 Π g resonance have previously had substantial disagreement, and also where the EELS results must now be expected to show violations of the first Born approximation. After correcting for this contamination, the a 1 Π g GOS from the NIXS results is in good agreement with prior theory. The NIXS spectra, over their entire q range, also find satisfactory agreement with the new TDDFT calculations for both bound and continuum excitations.

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Section: Resultssupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Reexamining the Lyman-Birge-Hopfield band of N2

et al. 2011

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“…The low cross section has obscured the use of NRIXS for samples with low electron density, and most XRS studies have therefore focused on liquids and solids. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Nevertheless, during the last few years developments in synchrotron radiation instrumentation 18,19 have extended the feasibility of the technique to new materials, phases, and experimental conditions. Experiments for gaseous samples have become feasible for sample cells where relatively high gas pressures can be realized.…”

Section: X-ray Raman Scatteringmentioning

confidence: 99%

Inelastic X-ray scattering and vibrational effects at the K-edges of gaseous N2, N2O, and CO2

Sakko

Galambosi

Inkinen

et al. 2011

Phys. Chem. Chem. Phys.

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We report non-resonant inelastic X-ray scattering experiments of several gaseous samples in the inner-shell excitation energy range. The experimental near-edge spectra from all the K-edges of N(2), N(2)O, and CO(2) including the momentum transfer dependence are presented. The results are analyzed using density functional theory calculations that accurately reproduce the experimental spectral features. We observe vibrational effects in the measured spectrum and in the calculations the atomic motion is modeled using the Franck-Condon approximation and the linear coupling model. Our findings show that vibrational effects cannot be neglected in the analysis of high resolution inelastic X-ray scattering spectroscopy. The results also support the validity of the transition potential approximation for calculating core excited state potential energy surfaces.

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“…Apparently, amorphous SiO is not a simple composite of amorphous Si and SiO 2 clusters but may have a unique atomic structure, possibly, in the interfacial regions between Si and SiO 2 domains as suggested by Hohl and co-authors 12 . Nevertheless, in spite of extensive investigations by XRD, X-ray photoelectron spectroscopy, X-ray Raman scattering, small-angle X-ray scattering and so on 12 20 21 22 , these techniques only provide average or spectroscopic information on the structure of the amorphous SiO. The unique and well-defined local atomic configurations of SiO have not been directly realized by experiments mainly because of the limitation in spatial resolution of conventional diffraction methods.…”

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confidence: 99%

Atomic-scale disproportionation in amorphous silicon monoxide

et al. 2016

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Solid silicon monoxide is an amorphous material which has been commercialized for many functional applications. However, the amorphous structure of silicon monoxide is a long-standing question because of the uncommon valence state of silicon in the oxide. It has been deduced that amorphous silicon monoxide undergoes an unusual disproportionation by forming silicon- and silicon-dioxide-like regions. Nevertheless, the direct experimental observation is still missing. Here we report the amorphous structure characterized by angstrom-beam electron diffraction, supplemented by synchrotron X-ray scattering and computer simulations. In addition to the theoretically predicted amorphous silicon and silicon-dioxide clusters, suboxide-type tetrahedral coordinates are detected by angstrom-beam electron diffraction at silicon/silicon-dioxide interfaces, which provides compelling experimental evidence on the atomic-scale disproportionation of amorphous silicon monoxide. Eventually we develop a heterostructure model of the disproportionated silicon monoxide which well explains the distinctive structure and properties of the amorphous material.

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Suboxide interface in disproportionatinga-SiO studied by x-ray Raman scattering

Cited by 14 publications

References 51 publications

Reexamining the Lyman-Birge-Hopfield band of N2

Reexamining the Lyman-Birge-Hopfield band of N2

Inelastic X-ray scattering and vibrational effects at the K-edges of gaseous N2, N2O, and CO2

Atomic-scale disproportionation in amorphous silicon monoxide

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