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SUMMARY:Three-dimensional imaging and analysis using aberration-corrected 
 STEM - Pete Nellist\, Department of Materials\, University of Oxford
DTSTART:20061204T150000Z
DTEND:20061204T160000Z
UID:TALK6025@talks.cam.ac.uk
CONTACT:Edmund Ward
DESCRIPTION:The ability to correct the spherical aberration inherent in th
 e electron lenses of the scanning transmission electron microscope is crea
 ting a number of new opportunities.  In this talk we shall explore a numbe
 r of ways that we can use aberration-corrected STEM for three-dimensional 
 investigations of materials.\n \nThe first application makes use of the fa
 ct that correction of spherical aberration leads to enhanced visibility of
  supported nanostructures\, and has allowed the crystal structure of inorg
 anic MoSI nanowires to be determined by recording high resolution images f
 rom a variety of orientations. \n\nA second approach is to make use of the
  reduced depth of field that results from aberration correction.  Bloch wa
 ve calculations for zone-axis crystals demonstrate that there are two scat
 tering effects that can displace the crossover from the desired focal plan
 e within the sample\, and that certain depths may be completely inaccessib
 le.\n\nFinally\, we will discuss the possibility of performing optical sec
 tioning using a double aberration-corrected instrument operating in a conf
 ocal mode. Recent calculations analysing this new imaging mode will be pre
 sented\, and some experimental data demonstrating the feasibility of the c
 onfocal trajectories.
LOCATION:T001 [Tower Seminar Room]\, Materials Science and Metallurgy\, De
 partment of
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