The 1Å Double Aberration Corrected In-situ TEM/STEM Project at York

An ultra high resolution (1Å) Field Emission Transmission Electron Microscope, with Cs Aberration Correctors for both TEM and STEM, in purpose built accommodation with remote control and microanalysis for:

  • Atomic resolution imaging
  • Atomic column analysis
  • Dynamic in-situ transformation and processing studies

The instrument

This instrument is based on a unique high performance JEOL 2200 FS TEM and STEM system with Cs aberration correctors for both TEM imaging and on the 1Å high angle annular dark field (HAADF) STEM probe; as determined by the transforms of Si (110) images.

It is one of the world’s forefront electron microscopes with 1Šresolution but the capability which sustainably differentiates the York JEOL 2200 FS system is the facility for dynamic in-situ experiments under operational conditions of controlled temperature and in future gas environments.

Experiments

Dynamic in-situ experiments study the development of nanostructures with processing and access materials forms which are metastable with respect to temperature and where provided atmosphere.

In a single experiment the sequence of events in the development of nanoscale microstructures can be followed in real time with atomic resolution.

New science requires extraction of the maximum possible information from each unique image in an ever changing series; without the regular opportunity for through focal series and extensive post acquisition processing of multiple images.

We are pioneering the development of Aberration Corrected (AC) TEM and STEM for dynamic in-situ experiments and this is important in:

  • Promoting a contrast transfer function (CTF) extending to higher frequencies and spatial resolutions (1Å)
  • Allowing image recording at close to zero defocus, including to strengthen (and simplify interpretation) information at interfaces and surfaces
  • Greatly reducing the image distorting delocalisation effects of the Cs and defocus dependent CTF oscillations between 1Å and 3Å atomic spacings
  • Analysing small (<2nm) nanoparticles and clusters on supports, including with SMSI, using high resolution TEM as well as HR STEM
  • Facilitating HAADF STEM analysis of multiply twinned structures

Configuration

Uniquely among JEOL AC systems the York 2200 FS 2AC has both a gas tolerant TMP vacuum system and a wider gap HRP objective lens polepiece in order to accommodate a 1000ºC hot stage (delivered late December 2007) or other in-situ apparatus. The main downside with the HRP polepiece is a doubling of the natural Cs coefficient but the potentially deleterious influence of this on imaging is greatly moderated by the introduction of CEOS C3 aberration correction (Cs => ~0).

At York the JEOL 2200 FS is installed in a new purpose built pod with a separate "building in a building" construction, independent 18 meter deep foundations and a 100 ton base block of concrete for the column room. This is isolated from the power supplies and support services in separate rooms; as are the operators and remote (only) controls.

Early applications have included functionalised nanoparticle studies.