Specimen Preparation for SIMS

Facilities for specimen preparation include:

  • Laminar flow hood
  • Dry box containment
  • Ultra-sonic bath
  • Metal or carbon coating as required for insulating surface analysis can be done in the electron microscopy facility
  • Optical microscopy examination
  • TEM grid mounting
  • Sample holders for pre-tilting prior to mounting

Oxygen, hydrogen and carbon tracer isotope labelling

The Solid Oxide Fuel Cell group in the Materials Department and lead by Professor John Kilner has an extensive facility within the Department of Materials for the thermal treatment of samples in atmospheres enriched in the tracer isotopes of oxygen, hydrogen and carbon. This facility has been used extensively together with the SIMS depth profiling instrumentation in the Surface Analysis Facility to measure the oxygen mass transport in oxides that have application in a number of high temperature electrochemical devices such a Solid Oxide Fuel Cells.

Use of this facility would require full consultation with Professor John Kilner incuring costs that have to be separately negotiated.

The dry oxygen-18 gas thermal treatment equipment

Instrumentation

The Surface Analysis Facility incorporates SIMS, LEIS, FIB and optical interferometry. The facility provides state of the art analyses of a wide range of surfaces using time of flight secondary ion mass spectrometry (ToF-SIMS), low energy ion scattering (LEIS), and focussed ion beam (FIB) microscopy with secondary ion mass spectrometry (SIMS).

ToF-SIMS is a ultra-high vacuum-based technique for measuring the chemical nature of atoms at and near the surface of materials. The sensitivity of the measurement is often better than parts per million, and the spatial resolution can be within the nano-scale.

Low energy ion scattering (LEIS) is a highly surface sensitive technique, capable of measuring the chemical composition of just the first atomic monolayer. The facility is unique to the UK and one of but a few in the world.

The above two techniques are also interconnected allowing sample interchange without exposure to the atmosphere and maintaining UHV conditions. Sample preparation facilities are available for top atom and molecule layer characterisation by LEIS and SIMS.

Combined TOF SIMS and LEIS instrument

Combined TOF SIMS and LEIS instrument

Focussed Ion Beam (FIB) microscopy is also used for site-specific preparation of thin membranes for transmission electron microscopy. This method is particularly suitable for composite, macro-porous or fragile materials. The FIB instrument also has SIMS capabilities and can be used for depth profiling, ion mapping as well as sequential ‘slice and view’ technique imaging. 3D reconstruction of the microstructure after Matlab-based image analysis is done using SPIERS or AMIRA software packages.

Finally, the microscope-based coherence scanning interferometer enables high resolution measurement of surface topography, including sputtered crater depths.

Research is undertaken at the surface analysis facility in a range of disciplines, including but not limited to oxide materials for fuel cells, biomaterials, functional nanomaterials, and energy and transportation materials. Much of the research, such as materials for fuel cells, relies on the facility’s isotopic tracer labelling facility and Matlab-based modelling routines for the interpretation of the tracer fraction profile. Research in the facility has resulted in over 40 PhDs and 500 publications.