“New dimensions in aberration-corrected scanning transmission electron microscopy: phase contrast, optical sectioning and confocal methods”
Professor Peter Nellist, University of Oxford
Short biography: Pete Nellist is Professor of Materials at the University of Oxford. He is the Oxford consortium member of the EPSRC SuperSTEM Mid-Range facility, and is currently President of the Royal Microscopical Society. He is a former Chair of the Electron Microscopy and Analysis Group of the Institute of Physics. He took his first degree and PhD from Cambridge, and has since then worked in research in the USA, Ireland and the UK, including the Universities of Cambridge, Birmingham, and Trinity College Dublin. In the USA he has worked at Oak Ridge National Laboratory and Nion Co. He has been at Oxford since 2006.Nellist’s research focuses in the development and applications of atomic resolution imaging and spectroscopy techniques, in particular the use of scanning transmission electron microscopy (STEM). A particular focus is the development of methods that expand the range of applicability of these methods. His application interests include catalyst nanoparticles, structural defects in III-N semiconductors, and the development of low-dose STEM techniques for soft and biological materials.
Thursday, April 30th 2015, 2.00pm
Schrödinger Building (SR3-006), University of Limerick
Tea/coffee will be available at 1.00pm outside SR3-006
Chaired by Prof. Ursel Bangert, Department of Physics and Energy(link is external) & Materials and Surface Science Institute (MSSI), University of Limerick
Abstract: Devices to correct for the inherent spherical aberration of electron lenses have been available for more than a decade now, and have had a particular impact in the field of scanning transmission electron microscopy (STEM). Imaging and spectroscopy at atomic resolution is now possible, and these capabilities are changing the way we can characterise materials. Here, however, I will explore some of the other new microscopy opportunities created by the development of aberration correction in STEM. I will show how the larger numerical aperture leads to a reduced depth of focus that can be exploited in both a confocal geometry and in wide-field mode to provide three-dimensional mapping of composition and strain fields. In a separate development, I will show how a combination of aberration correction and pixelated detectors can make the STEM a highly efficient phase contrast imaging device without the need for aberrations or phase plates, creating new opportunities for imaging light elements and soft materials.