ME-EM Graduate Seminar: Correlative microscopy for in situ characterization of catalyst nanoparticles under reactive environments

dec4aThe ME-EM Graduate Seminar speaker on Thursday, December 4th at 4:00 in 103 EERC will be Dr. Renu Sharma from National Institute of Standards and Technology, Center for Nanoscale Science and Technology.

The title of her presentation will be ‘Correlative microscopy for in situ characterization of catalyst nanoparticles under reactive environments’.

In recent years the environmental transmission scanning electron microscope (ESTEM) has been success-fully employed to elucidate the structural and chemical changes occurring in the catalyst nanoparticles un-der reactive environments. While atomic-resolution images and the combination of high spatial and energy resolution is ideally suited to distinguish between active and inactive catalyst particles and identify active surfaces for gas adsorption, unambiguous data can only obtained from the area under observation. This lack of statistical information available from TEM measurements is generally compensated for by using other, ensemble measurement techniques such as x-ray or neutron diffraction, x-ray photoelectron spec-troscopy, infrared spectroscopy, Raman spectroscopy etc. However, it is almost impossible to create iden-tical experimental conditions in two separate instruments to make measurements that can be directly com-pared. Moreover, ambiguities in ESTEM studies may arise from the unknown effects of the incident elec-tron beam and uncertainty of the sample temperature. We have designed and built a unique platform that allows us to concurrently measure atomic-scale and micro-scale changes occurring in samples subjected to identical reactive environmental conditions by incorporating a Raman Spectrometer on the ESTEM. We have used this correlative microscopy platform i) to measure the temperature from 60 μm2 area using Ra-man shifts, ii) to investigate light/matter interactions iii) as a heating source, iii) for concurrent optical and electron spectroscopy such as cathodoluminescence, EELS and Raman. Details of the design, function, and capabilities will be illustrated with results obtained from in situ combinatorial measurements.

Renu Sharma is a Project Leader in the Nanofabrication Research Group. She received a B.S. and B.Ed. in Physics and Chemistry from Panjab University, India, and M.S. and Ph.D. degrees in Sol-id State Chemistry from the University of Stockholm, Sweden, where she had a Swedish Institute Fellowship. Renu joined the CNST in 2009, coming from Arizona State University (ASU), where she began as a Faculty Research Associate in the Department of Chemistry and Biochemistry and the Center for Solid State Science, and most recently served as a Senior Research Scientist in the LeRoy Eyring Center for Solid State Science and as an affiliated faculty member in the School of Materials and Department of Chemical Engineering. Renu has been a pioneer in the development of environmental scanning transmission electron microscopy (E(S)TEM), combining atomic-scale dynamic imaging with chemical analysis to probe gas-solid reactions. She has applied this powerful technique to characterize the atomic-scale mechanisms underlying the synthesis and reactivity of nanoparticles (including catalysts), nanotubes, nanowires, inorganic solids, ceramics, semiconductors, and superconductor materials. Renu has received a Deutscher Akademischer Austauschdienst (DAAD) Faculty Research Fellowship, is a past President of the Arizona Im-aging and Microanalysis Society, and has given over 70 invited presentations, and published 3 book chapters and over 160 research articles. At the CNST, Renu is establishing advanced E(S)TEM measurement capabilities for nanoscience re-search and contributing her research expertise to the operation of a new TEM facility in the NanoFab.