July 17, 2012 Noon-1PM
Texas Instruments Auditorium E-1
2900 Semiconductor Drive. Santa Clara, CA
Nanoscale Chemical Imaging of Energy Materials with Full-field Transmission X-ray Microscopy
Dr. Joy C. Andrews, SLAC National Accelerator Laboratory
Correlation of chemistry and morphology in hierarchical functional materials such as battery electrodes, fuel cells and catalysts can drive design of more efficient materials. Full-field nanoscale chemical imaging has been used to collect single-pixel XANES (~1E6 spectra per energy stack; acquired in minutes) at down to 30 nm resolution. The full-field transmission X-ray microscope (TXM) on beam line 6-2 at the Stanford Synchrotron Radiation Lightsource combines large field of view (tens to hundreds of microns) with high resolution imaging from ~4.5 to 14 keV (ΔE/E < 1E-4), for XANES chemical speciation. Custom software (TXM Wizard; available free for public use) is used to produce chemical and morphological maps of various composite systems in 2D and 3D. In situ and ex situ results from full-field XANES microscopy of Li-ion battery electrodes and other catalytic materials, rendering insight into performance and structure, will be presented.
Dr. Joy C. Andrews is a Staff Scientist, Stanford Synchrotron Radiation Lightsource, SLAC. She performs interdisciplinary research in nanoscience on energy-related materials, correlating nanostructure and chemical state ex situ, in situ and in operando, for improvement of performance and uptake and transformation of metals and nanoparticles in environmental samples. She also studies speciation of heavy metals using X-ray absorption spectroscopy (XAS), scanning x-ray fluorescence and full field hard x-ray transmission microscopy as well as other methods. At SLAC, she leads the development of spectroscopic imaging, and in situ imaging of energy materials and catalytic systems. She obtained her PhD from the University of California Berkeley. Prior to SLAC, she was a full professor at the Department of Chemistry and Biochemistry, CSU East Bay, CA and is currently the Professor Emeritus.