Date: Thursday, Jan 26th
Presenter: Nigel D. Browning, Chief Scientist for Chemical Imaging and Laboratory Fellow, Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory
The last few years have seen a paradigm change in (scanning) transmission electron microscopy with unprecedented improvements in spatial, spectroscopic and temporal resolution being realized by aberration correctors, monochromators and pulsed photoemission sources. Spatial resolution now extends to the sub-angstrom level, spectroscopic resolution into the sub-100meV regime and temporal resolution for single shot imaging is now on the nanosecond scale. However, to fully utilize these instrumentation developments to study both structures and processes, in-situ stages to control the environment around the sample must also be employed. In this presentation, the development and implementation of two environmental stages will be discussed: an in-situ gas stage that allows atmospheric pressure in a range of reactive gases to be maintained around the sample while atomic resolution images are obtained, and an in-situ liquid that allows atomic scale images and electron energy loss spectra to be obtained from samples suspended in solution. By utilizing a novel laser heating source, temperatures up to 2000 C can also be obtained in small areas of the sample using both of these stages. Utilizing these capabilities allows for direct imaging of oxidation and reduction processes in metals, ceramics and catalytic systems as well as a wide range of applications to studying corrosion in materials science and live biological systems. These stages have been designed to be incorporated into both high spatial resolution aberration corrected (S)TEM as well as into high temporal resolution Dynamic TEM (DTEM). In addition to describing recent results on both of these types of microscopes, the potential for future experiments will also be discussed in relation to the development of new microscopes at PNNL.
Pacific Northwest National Laboratory is operated by Battelle Memorial Institute for the U.S. Department of Energy under Contract No. DE-AC05-76RL01830.
Nigel Browning is currently a Laboratory Fellow and Chief Scientist for Chemical Imaging at Pacific Northwest National Laboratory (PNNL). He received his undergraduate degree in Physics from the University of Reading, U. K. and his Ph. D. in Physics from the University of Cambridge, U. K. After completing his Ph. D. in 1992, he joined the Solid State Division at Oak Ridge National Laboratory (ORNL) as a postdoctoral research associate before taking a faculty position in the Department of Physics at the University of Illinois at Chicago (UIC) in 1995. In 2002, he moved to the Department of Chemical Engineering and Materials Science at the University of California-Davis (UCD) and also held a joint appointment in the National Center for Electron Microscopy (NCEM) at Lawrence Berkeley National Laboratory (LBNL). In 2005 he moved the joint appointment from LBNL to Lawrence Livermore National Laboratory (LLNL) to become project leader for the Dynamic Transmission Electron Microscope (DTEM). In 2009, he also joined the Department of Molecular and Cellular Biology at UCD to focus on the development of the DTEM to study live biological structures. He has over 20 years of experience in the development of new methods in electron microscopy for high spatial, temporal and spectroscopic resolution analysis of engineering and biological structures. His research has been supported by DOE, NSF, NIH, DOD and by industry, leading to research projects for over 30 graduate students and 29 postdoctoral research fellows. He received the Burton Award from the Microscopy Society of America in 2002 and the Coble Award from the American Ceramic Society in 2003 for the development of atomic resolution methods in scanning transmission electron microscopy (STEM). With his collaborators at LLNL he also received RD 100 and Nano 50 Awards in 2008, and a Microscopy Today Innovation Award in 2010 for the development of the dynamic transmission electron microscope (DTEM). He has over 350 publications and has given over 200 invited presentations on the development and application of advanced TEM methods.