SuperSTEM is the EPSRC National Facility for Aberration Corrected STEM and is operating under the auspices of an academic consortium consisting of the Universities of Glasgow, Leeds, Liverpool, Manchester and Oxford. It also has collaboration agreements with four further partner universities: Cambridge, Sheffield, York and Warwick. 

SuperSTEM revolves around its central hub, a purpose-designed building housing two state-of-the-art aberration corrected STEM instruments on the STFC Daresbury Campus. Four additional aberration-corrected microscopes are available at the consortium universities and a further three at the partner universities, for projects that require complementary capabilities to those available on the main Daresbury site

Access to SuperSTEM is free at the point of use for EPSRC eligible UK researchers and their worldwide collaborators, as well as to RCUK ticket holders. Other access is subject to funding. We also welcome applications from commercial institutions, please contact us for commercial rates.

The SuperSTEM microscopes (a VG HB 501 with Nion MkII Cs corrector and a Nion UltraSTEM 100) at the SuperSTEM facility can analyse single atoms and columns of atoms using scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS).  Apart from optimised performance the UltraSTEM™ 100 has 5th order aberration correction, a 2 Å electron probe mode with >0.5 nA current for rapid atomic-scale EELS mapping as well as a nano-diffraction mode. A silicon drift EDS detector was recently installed for chemical analysis using X-ray spectroscopy. SuperSTEM offers various sample finishing facilities and runs a 10-node cluster used for simulations.

To fully benefit from aberration correction all other impeding factors such as mechanical vibrations, temperature oscillations, humidity or electromagnetic interference have to be minimized. 

The chosen site for SuperSTEM at the STFC Daresbury Laboratories has excellent geological stability due to a sandstone bedrock with stratified rocks. The building itself was designed to minimise vibrations by separating the foundations of the microscope rooms from the main building foundations ("house-in-house" concept). This structure also provides excellent accoustical isolation and damping.

In addition, electrical wiring designed to minimise interference, separate electrical supplies, computer-controlled air handling, close temperature control and air conditioning with low long term oscillation characteristics ensure reliable microscopy.

History of SuperSTEM

The SuperSTEM project began in 1997 when Prof. Mick Brown presented a paper at the EMAG conference in Cambridge entitled "A Synchrotron in a Microscope".

He challenged the UK microscopy community to pool resources to exploit the emerging technology of spherical aberration correction. Prof. Ondrej Krivanek, one of the pioneers in the field, had recently returned to Cambridge to work with Prof. Brown in the Microstructural Physics group and had successfully developed a prototype corrector for STEM. Building on this breakthrough, the SuperSTEM project was funded by the Engineering and Physical Sciences Research Council (EPSRC) in 2001 with the goal to realise Prof. Brown's vision. By that stage, it consisted of lead scientists from the Universities of Liverpool, Cambridge and Leeds with Prof. Peter Goodhew as the principal investigator and Prof. Andrew Bleloch as its director. The final makeup was largely serendipitous because the project had had strong support from a large number of people and organisations and with the addition of Glasgow University it has proved a very effective team.

SuperSTEM was the first facility in Europe to adopt aberration correction by incorporating a Nion quadrupole-octupole correction system into a VG STEM as early as spring 2002.

The First Instrument

The first instrument (SuperSTEM1) is based on the Cambridge VG HB 501UX dedicated STEM, which was retro-fitted with a Nion MkII quadrupole-octupole aberration corrector, an improved design from the prototype developed at Cambridge by Prof. Krivanek.

As a result the spatial resolution was doubled from ~2 Å to below 1 Å. 

The Second Instrument

Many new and important results have been obtained on this microscope but from the beginning it was clear that the 30 year old design of the VG microscopes was not optimised for aberration correction. Nion's response was to build an entirely new microscope, the UltraSTEM™ 100, that overcame these difficulties. SuperSTEM2 was the first such instrument in use for scientific research. 

It provides sub-Angstrom resolution with 5th order aberration correction, while its electron optical system provides great flexibility for applications such as electron energy loss elemental mapping at atomic resolution or diffractive imaging. A silicon drift EDX detector was recently fitted with a view to provide simultaneous X-ray and EELS mapping capabilities.

A Third Instrument

SuperSTEM's aim is to embrace the latest innovations in electron source monochromation technology and chromatic aberration correction through the installation of a third instrument. Implementing chromatic aberration correction will provide high spatial resolution at the low acceleration voltages required to minimise radiation damage. Incorporating efficient monochromation will make new spectroscopic information accessible in the core-loss, plasmonic and possibly even phonon region of the EELS spectrum:

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