Liquid-phase transmission electron microscopy offers a unique combination of nanometer spatial resolution and millisecond temporal resolution. It has provided many useful insights into nanoscale reaction dynamics but achieving sub-nanometer resolution has proved difficult due to limitations in the current liquid cell designs. For this reason, atomic resolution TEM investigations of dynamic chemical processes are generally achieved by a snap shot method, where the experiment is frozen at suitable time points (for a recent example of studying ion exchange in atomically thin clays see [1]). In this talk I will present results showing atomic resolution liquid phase scanning transmission electron microscopy investigations enabled using insights from 2D materials nanochannel fluidics [2,3] and achieved with our two-dimensional heterostructure-based graphene liquid cells [4]. I will demonstrate that the approach facilitates in situ atomic resolution imaging and elemental analysis to investigate the time evolution of calcium carbonate synthesis, from the earliest stages of nanodroplet precursors to crystalline calcite in a single experiment [4]. I will also demonstrate the latest application of the technique to studying the dynamic motion and preferred resting sites of single atom metallic species on surfaces in aqueous salt solution.
[1] Ion exchange in atomically thin clays and micas. Zou et al. Nature Materials (2021) https://www.nature.com/articles/s41563-021-01072-6
[2] Capillary condensation under atomic-scale confinement, Q Yang et al, Nature 588 (7837), 250-253 (2020);
[3] Ballistic molecular transport through two-dimensional channels, A Keerthi et al, Nature 558 (7710), 420-424 (2018);
[4] Nanometer resolution elemental mapping in graphene-based TEM liquid cells, Kelly et al Nano Letters (2018) 18 (2), 1168-1174
[5] In situ TEM imaging of solution-phase chemical reactions using 2D-heterostructure mixing cells Kelly et al, Advanced Materials, (2021) https://onlinelibrary.wiley.com/doi/full/10.1002/adma.202100668
Biography
Sarah Haigh is Professor of Materials in the Department of Materials at University of Manchester, Director of the Electron Microscopy Centre and Director of the bp International Centre for Advanced Materials (ICAM). Her group applies advanced transmission electron microscopy (TEM) techniques to understand nanomaterial behaviour and she holds an ERC Starter Grant developing in situ TEM techniques. She completed her MEng and DPhil degrees in Material Science at the University of Oxford, then worked as TEM application specialist for JEOL UK before beginning a lectureship at the University of Manchester in 2010. She has published over 200 peer reviewed journal papers, including over 40 as corresponding author, and 5 book chapters.