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L3 White line Splitting of Copper in the Electron Energy loss Spectrum of YBa2Cu3O7−x

Published online by Cambridge University Press:  28 February 2011

Charming C. Ahn ,
David S. Lee  and
Konrad Samwer
Charming C. Ahn
Affiliation:
California Institute of Technology, Keck Laboratory of Engineering Materials, Pasadena, CA 91125
David S. Lee
Affiliation:
California Institute of Technology, Keck Laboratory of Engineering Materials, Pasadena, CA 91125
Konrad Samwer
Affiliation:
also, I. Physikalisches Institut der Universität Göttingen/FRG
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Abstract

We have used electron energy loss spectroscopy (EELS) in a transmission electron microscope (TEM) to probe the L23 excitation of the 930 eV copper 2p to 3d transition in YBa2Cu3O7−x. Unlike UPS and XPS which are surface sensitive, EELS permits analysis of bulk properties from submicron regions of a single crystal. In addition, EELS probes the lowest unoccupied states and is particularly suited to the analysis of Cu valance states in YBa2Cu3O7−x We observe a splitting of the L33 peak of ∼2.7 eV, which we attribute to contributions from both Cu 2+ and Cu 3+. The intensity contribution Cu 3+ is maximized when a two beam condition is used to enhance channeling of the electrons between the {033} planes of the crystal near a [100] orientation. Upon prolonged exposure of the compound to the incident electron beam, the splitting disappears and the only contribution to the L3 white line is from divalent copper.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 99: Symposium AA – High-Temperature Superconductors , 1987 , 793
Copyright
Copyright © Materials Research Society 1988

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References

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