Momentum-transfer resolved electron energy loss spectroscopy of solids: problems, solutions and applications

Y. Y. Wang; S. C. Cheng; V. P. Dravid; F. C. Zhang

doi:10.1016/0304-3991(95)00022-S

Momentum-transfer resolved electron energy loss spectroscopy of solids: problems, solutions and applications

Y. Y. Wang^*, S. C. Cheng, V. P. Dravid, F. C. Zhang

^*Corresponding author for this work

Materials Science and Engineering

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22 Scopus citations

Abstract

The critical issues in experimental momentum-transfer (q) resolved EELS in TEM are outlined. It is shown that despite the presence of various multiple scattering events, meaningful information about the symmetry of electronic states can be obtained. Such q-resolved electron energy loss spectroscopy of the valence band transitions in BaBiO₃ has revealed that the dispersion of the optical gap (∼ 2 eV) with q is anisotropic and that an optically forbidden transition is present at 4.5 eV. The oscillator strength of the forbidden transition is stronger for q along [100], but weaker along [110]. A molecular orbital model is proposed and the forbidden transition is assigned to be the excitation from the O 2pσ non-bonding states to the empty Bi (6s) state. The model is in good agreement with the physical properties of the transition.

Original language	English (US)
Pages (from-to)	109-119
Number of pages	11
Journal	Ultramicroscopy
Volume	59
Issue number	1-4
DOIs	https://doi.org/10.1016/0304-3991(95)00022-S
State	Published - Jul 1995

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials
Atomic and Molecular Physics, and Optics
Instrumentation

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title = "Momentum-transfer resolved electron energy loss spectroscopy of solids: problems, solutions and applications",

abstract = "The critical issues in experimental momentum-transfer (q) resolved EELS in TEM are outlined. It is shown that despite the presence of various multiple scattering events, meaningful information about the symmetry of electronic states can be obtained. Such q-resolved electron energy loss spectroscopy of the valence band transitions in BaBiO3 has revealed that the dispersion of the optical gap (∼ 2 eV) with q is anisotropic and that an optically forbidden transition is present at 4.5 eV. The oscillator strength of the forbidden transition is stronger for q along [100], but weaker along [110]. A molecular orbital model is proposed and the forbidden transition is assigned to be the excitation from the O 2pσ non-bonding states to the empty Bi (6s) state. The model is in good agreement with the physical properties of the transition.",

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T1 - Momentum-transfer resolved electron energy loss spectroscopy of solids

T2 - problems, solutions and applications

AU - Wang, Y. Y.

AU - Cheng, S. C.

AU - Dravid, V. P.

AU - Zhang, F. C.

PY - 1995/7

Y1 - 1995/7

N2 - The critical issues in experimental momentum-transfer (q) resolved EELS in TEM are outlined. It is shown that despite the presence of various multiple scattering events, meaningful information about the symmetry of electronic states can be obtained. Such q-resolved electron energy loss spectroscopy of the valence band transitions in BaBiO3 has revealed that the dispersion of the optical gap (∼ 2 eV) with q is anisotropic and that an optically forbidden transition is present at 4.5 eV. The oscillator strength of the forbidden transition is stronger for q along [100], but weaker along [110]. A molecular orbital model is proposed and the forbidden transition is assigned to be the excitation from the O 2pσ non-bonding states to the empty Bi (6s) state. The model is in good agreement with the physical properties of the transition.

AB - The critical issues in experimental momentum-transfer (q) resolved EELS in TEM are outlined. It is shown that despite the presence of various multiple scattering events, meaningful information about the symmetry of electronic states can be obtained. Such q-resolved electron energy loss spectroscopy of the valence band transitions in BaBiO3 has revealed that the dispersion of the optical gap (∼ 2 eV) with q is anisotropic and that an optically forbidden transition is present at 4.5 eV. The oscillator strength of the forbidden transition is stronger for q along [100], but weaker along [110]. A molecular orbital model is proposed and the forbidden transition is assigned to be the excitation from the O 2pσ non-bonding states to the empty Bi (6s) state. The model is in good agreement with the physical properties of the transition.

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Momentum-transfer resolved electron energy loss spectroscopy of solids: problems, solutions and applications

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