PhD students in the ASP group are fully involved in the research and are expected to contribute to publications and make presentations at international conferences at the earliest possible opportunity.

We encourage our students to take advantage of the many trans-national skill development opportunities in the areas of SIMS, X-ray methods, and Heritage science.  The work involves extensive collaboration with other academic centres across the EU and the rest of the world, scientific instrument manufacturers, museums, and other institutions. 

New sources for ion microscopy

Ion microscopy is a technique widely used in semiconductor, pharmacutical and geological research.  It also has applications in astrophysics (for example, the identification and dating of pre-solar grains).  In general, it is a technique for obtaining spatially resolved chemical analyses at high sensitivity and resolution.  For samples from nanostructures to cells the technique can provide vital information on the spatial location of such things as dopant distributions, impurity clusters and drug tags. 

The ASP group has completed the first-stage development of two novel sources for the generation of ion beams for ion microscopy.  These are a gold cluster negative ion source, and a positive caesium source based on a new physical principle.  The gold source is intended for the study of large molecular clusters, and the caesium source offers the practical possibility, for the first time, of high sensitivity analysis based  on an intense sub-micron caesium spot. 

This fledgling technology requires considerable refinement and redesign, along with extensive applications testing in leading areas of condensed matter physics.

Students involved with this project will be trained in an analytical technique which is key in many industries, and will gain extensive experience in all aspects of scientific instrument development from computer simulation to final engineering. 

The opportunity exists to apply any new equipment developed to the study of advanced semiconducting materials, cultural heritage (conservation) research, and in other areas. 

Optically detected X-ray absorption microscopy (ODXAM)

When X-rays with energies above the core levels interact with the atoms of a substance, they create core level ionization through the emission of a photo-electron.  Spontaneous neutralization of the core level holes gives rise to characteristic X-ray and Auger electron emission, which can be detected outside the material.  The probability of ionization depends upon the energy above the core level of the exciting X-ray, and the positions of the atoms near the ion.  These create interference effects in the photoelectron wave which modulate the X-ray emission spectrum allowing the local atomic and electronic structures to be deduced.  This is the basis of X-ray absorption spectroscopy (XAS).