« Foundry Home Page

Date: Tuesday, May 24, 2016
Time: 11:00 am
Speaker: Ondrej Krivanek, Nion
Title: Atomic-Resolution and Vibrational Studies of Materials by Aberration-Corrected Scanning Transmission Electron Microscopy
Location: 67-3111 Chemla Room


Abstract:

Aberration-corrected scanning transmission electron microscopes (AC-STEMs) are able to form electron probes as small as 0.5 Å in diameter, and they can image and spectroscopically analyze single atoms in-situ.  NCEM and Nion have pioneered many of these advances. Nion’s main achievements include developing the world’s first aberration corrector that improved spatial resolution of an electron microscope to better than 1 Å, and designing a whole new STEM of unprecedented stabilities that can efficiently acquire high quality elemental and chemical maps, and also spectra from single atoms, both by EELS (electron energy loss spectroscopy) and EDXS (energy-dispersive X-ray spectroscopy). 

More recently, we have introduced a monochromated STEM system for electron energy loss spectroscopy (EELS), which has made vibrational spectroscopy possible at an energy resolution better than 10 meV, and a spatial resolution of a few nm [1]. This instrument is now opening unexpected new vistas on the world of materials, such as being able to analyze the types of hydrogen bonds present in a sample, and performing damage-free vibrational spectroscopy, both in aloof [2] and “leapfrog scanning” [3] modes.

This seminar will review the basic principles behind the new developments, illustrate them with experimental results from a variety of materials, and discuss and illustrate especially inviting future directions.