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The 1s-State Analysis Applied to High-Angle, Annular Dark-Field Image Interpretation—When Can We Use It?

Published online by Cambridge University Press:  22 January 2004

Geoffrey R. Anstis
Geoffrey R. Anstis
Affiliation:
Department of Applied Physics, University of Technology, Sydney, P.O. Box 123, Broadway, NSW 2007, Australia
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Abstract

A small probe centered on an atomic column excites the bound and unbound states of the two-dimensional projected potential of the column. It has been argued that, even when several states are excited, only the 1s state is sufficiently localized to contribute a signal to the high-angle detector. This article shows that non-1s states do make a significant contribution for certain incident probe profiles. The contribution of the 1s state to the thermal diffuse scattering is calculated directly. Sub-Ångstrom probes formed by Cs-corrected lenses excite predominantly the 1s state and contributions from other states are not very large. For probes of lower resolution when non-1s states are important, the integrated electron intensity at the column provides a better estimate of image intensity.

Keywords

high-resolution electron microscopyscanning transmission electron microscopyhigh-angle annular dark-field imaging1s statethermal diffuse scatteringmultislice methodfrozen phonon
Type
Research Article
Information
Microscopy and Microanalysis , Volume 10 , Issue 1 , February 2004 , pp. 4 - 8
Copyright
© 2004 Microscopy Society of America

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References

REFERENCES

Anderson, S.C., Birkeland, C.R., & Cockayne, D.J.H. (1997). An approach to quantitative compositional profiling at near-atomic resolution using high-angle annular dark field imaging. Ultramicroscopy 69, 83–103.Google Scholar
Anstis, G.R. (1996). Corrections to atomic scattering factors for high-energy electrons arising from atomic vibrations. Acta Cryst A 52, 450–455.Google Scholar
Anstis, G.R. (2001). Imaging point defects using a transmission electron microscope with controllable spherical aberration. Philos Mag B 81, 1687–1699.Google Scholar
Anstis, G.R., Cai, D.Q., & Cockayne, D.J.H. (2003). Limitations on the s-state approach to the interpretation of sub-Ångstrom resolution electron microscope images and microanalysis. Ultramicroscopy 94, 309–327.Google Scholar
Cowley, J.M. (1988). Electron microscopy of crystals with time-dependent perturbations. Acta Cryst A 44, 847–853.Google Scholar
Cowley, J.M. (1995). Diffraction Physics (3rd ed.). Amsterdam, The Netherlands: Elsevier Science.
Dinges, C., Berger, A., & Rose, H. (1995). Simulation of TEM images considering phonon and electronic excitations. Ultramicroscopy 60, 49–70.Google Scholar
Howie, A. (1979). Image contrast and localized signal selection techniques. J Microsc 117, 11–24.Google Scholar
Loane, R.F., Xu, P., & Silcox, J. (1992). Incoherent imaging of zone axis crystals with ADF STEM. Ultramicroscopy 40, 121–138.Google Scholar
Pennycook, S.J. & Jesson, D.E. (1991). High-resolution Z-contrast imaging of crystals. Ultramicroscopy 37, 14–38.Google Scholar
Rafferty, B., Nellist, P.D., & Pennycook, S.J. (2001). On the origin of transverse incoherence in Z-contrast STEM. J Electron Microsc 50, 227–233.Google Scholar
Wang, Z.L. (1995). Dynamical theories of dark-field imaging using diffusely scattered electrons in STEM and TEM. Acta Cryst A 52, 569–585.Google Scholar
Wang, Z.L. & Cowley, J.M. (1989). Simulating high-angle annular dark-field STEM images including thermal diffuse scattering. Ultramicroscopy 31, 437–454.Google Scholar