When
Where
Dr. John Bradley
Lawrence Livermore National Laboratory
"Analytical SuperSTEM for Planetary Materials Science"
Abstract:
A new generation of (60-300 keV) scanning transmission electron microscope known generically as "SuperSTEM" provides enhanced analytical capabilities for interrogation of materials. Key electron optical innovations include spherical aberration (Cs) correctors that enable a sub-Å electron probe and sub-Å spatial resolution, and monochromators that reduce energy spread in the incident probe from ~1 eV in a conventional STEM to ~0.1 eV in SuperSTEM, comparable to XAS and XANES and with the additional benefit of >100X improved signal-to-noise. Crystal structures can be imaged and spectroscopically analyzed with single-atomic-column resolution. Liquids in fluid inclusions and implanted gases (including H and He) can be detected in-situ. Optical properties (UV-VIS-near IR) of extraterrestrial materials can be measured down to the nanoscale. Detection limits for minor/trace elements are improved such that quantitative measurements of some extend to the ~200 ppm level in electron transparent specimens.