Z-contrast imaging in an aberration-corrected scanning transmission electron microscope

Citation
Sj. Pennycook et al., Z-contrast imaging in an aberration-corrected scanning transmission electron microscope, MICROS MICR, 6(4), 2000, pp. 343-352
Citations number
38
Categorie Soggetti
Multidisciplinary,"Spectroscopy /Instrumentation/Analytical Sciences
Journal title
MICROSCOPY AND MICROANALYSIS
ISSN journal
14319276 → ACNP
Volume
6
Issue
4
Year of publication
2000
Pages
343 - 352
Database
ISI
SICI code
1431-9276(200007/08)6:4<343:ZIIAAS>2.0.ZU;2-#
Abstract
We show that in the limit of a large objective (probe-forming) aperture, re levant to a spherical aberration corrected microscope, the Z-contrast image of a zone-axis crystal becomes an image of the Bloch states. The limiting resolution is therefore the width of the Bloch states, which may be greater than that of the free probe. Nevertheless, enormous gains in image quality are expected from the improved contrast and signal-to-noise ratio. We pres ent an analytical channeling model for the thickness dependence of the Z-co ntrast image in a zone-axis crystal, and show that, at large thicknesses, c olumnar intensities become proportional to the mean square atomic number, Z (2).