Kroto Centre for High Resolution Imaging and Analysis
The Kroto Centre for High Resolution Imaging and Analysis is an advanced transmission electron microscopy (TEM) facility set up on North Campus for research at the forefront of world-leading resolution. The final instrument will provide 0.05nm (0.5Å) spatial resolution for materials analysis as well as single atom imaging and spectroscopy capability.
This is complemented in the Mappin Building by a fully analytical JEOL2010F (S)TEM and a JEOL Fabrika 6500F dual beam scanning electron microscope with focused Ga+ ion beam.
The JEOL 2200FSC microscope presently installed is a 200kV transmission electron microscope with Schottky-type field-emission gun, in-column energy filter and two aberration correctors. There are presently only about a handful of these machines world-wide.
The upper aberration corrector eliminates the opening error of the probe-forming condenser lens system. This allows us to either focus the electron beam to 1Å in diameter and perform scanning TEM (STEM) at this resolution, or we can use a larger aperture and produce an electron beam that is as large as on a conventional field-emission instrument but with much more current in it (several nA within a few Ångstrøms). This is useful for improving the signal-to-noise ratio and/or reducing the acquisition time and thus drift during mapping. Images are generated on a computer screen by reading out on-axis (bright field) or off-axis (annular dark-field) detectors that record electron intensities at each point of the scan. Alternatively, electron energy-loss or characteristic X-ray signals can be mapped point-by-point.
The lower aberration corrector eliminates the opening error of the main objective lens used for lattice imaging at high magnification with planar illumination. Images can be recorded on several CCD cameras that are fibre-optically coupled to scintillator coated screens. We can thus improve the point resolution down to 1Å also in this mode and at the same time reduce image delocalisation effects by practically eliminating all transfer gaps up to very high spatial frequencies. As a result of this, the edges of specimens, interfaces and surfaces now appear atomically sharp and can be studied in-situ.
There is also the possibility of energy-filtered imaging to map the distribution of certain elements, mostly light elements and transition metals, with ~1nm resolution and energy-dispersive X-ray microscopy with ~2nm resolution and relatively fast elemental mapping of the lateral distribution of heavy elements.
Two applications of the JEOL 2200FSC are available if you click on the link below.
Applications of the High Resolution Microscopes
The JEOL R005, our final instrument, will be similar in conception but have a cold field-emission gun for higher electron beam brightness and smaller energy spread, 300kV for even better resolution and a clamp shell shielding the sample holder even better from external influences, such as thermal fluctuations and sound vibrations. It will achieve 0.5Å resolution.
The Director of the Centre is Prof. Tony Cullis, the Deputy Director Dr. Thomas Walther and its Experimental Officer Dr. Ian M. Ross (from left to right).
