MSE Colloquium: Joerg Jinschek, Understanding structure-property relationships in nanomaterials by in situ electron microscopy

Abstract

The focus on efficient energy conversion, use and storage, as well as on environmental protecting technologies, relies strongly on the advancement of functional nanomaterials. Understanding the state and properties of such nanomaterials demands detailed insights, also on the atomic scale. 

To our advantage, atomic scale electron microscopy (EM), markedly advanced by utilizing recent hard- and software improvements, has become a powerful and indispensable tool for characterizing those nanostructures. Ongoing activities concentrate on methodological aspects of state-of-the-art EM and thereby open routes towards atom sensitive imaging of nanostructures (based even on light elements) that play a crucial role in numerous applications. The advancement in single atom imaging will be illustrated in case of imaging graphene, where ‘true atomic resolution’ has been achieved [1]. 
However, the actual state and function of nanomaterials ‘in operation’ cannot always be inferred from examination under standard EM high vacuum and room temperature conditions or from postmortem EM studies. In situ techniques enable visualization of structural evolution under operational (or environmental) conditions, thereby providing new insights in important materials science questions [2]. 

EM imaging schemes will be discussed that focus on maintaining spatial resolution in in situ studies, while controlling electron beam / structure interactions. For instance, the inherent atomic scale microscope resolution can indeed be retained in an aberration-corrected environmental microscope (ETEM) under optimized electron illumination conditions [3,4]. Further development in in situ heating stages enables quantitative atomic-scale studies at elevated temperatures in any (gaseous) environment [5]. I will describe the path to have an accurate knowledge and control of experimental conditions in advanced in situ EM experiments. Application examples will be presented, e.g. atomic scale visualization of solid heterogeneous catalysts and their structural evolution in reaction environments to obtain detailed knowledge about catalytic reaction mechanisms [6].

[1] J. R. Jinschek, et al., Carbon 49, 556 (2011)
[2] J. R. Jinschek, Chemical Communications 50, 2696 (2014)
[3] J. R. Jinschek et al., Micron 43, 1156 (2012)
[4] S. Helveg, et al., Micron 68, 176-185 (2015)
[5] L. Mele, et al., Microscopy Research and Technique, early view (2016)
[6] H. Yoshida et al., Science 335, 317 (2012)

Bio

Dr. Joerg R. Jinschek holds a doctoral degree in physics from the Friedrich-Schiller-University Jena, Germany. In 2001 he has been awarded a Feodor-Lynen-Fellowship of the Alexander-von-Humboldt Foundation (Germany). He carried out his postdoctoral research from 2001 to 2005 at the National Center for Electron Microscopy (NCEM / LBNL) in Berkeley/CA. From 2005 to 2007 he established a TEM lab as a Research Assistant Professor at Virgina Tech. In 2008 he joined FEI Company as a Senior Research Scientist. Currently he is responsible for in situ S/TEM research and the Chemistry segment in FEI’s Materials Science BU.