Electron Microscopy Facility

Hitachi HD2700C, a dedicated Scanning Transmission Electron Microscope (STEM)

Contacts: Sooyeon Hwang

This is a state-of-the-art dedicated 200kV cold field emission STEM with an aberration-corrector for the probe-forming lens. It is the first Hitachi-made aberration corrected electron microscope. The aberration corrector improves the spatial resolution (probe size) to <0.1 nm, while boosting the probe current to 200 pA. The instrument is optimized for spectroscopic imaging and simultaneous acquisition of “Z-contrast” images and electron energy-loss spectroscopy (EELS). It is equipped with five detectors for various settings using different convergent angles and collection angles in annular-dark-field imaging. It is also equipped with a high resolution electron energy-loss spectrometer which can routinely achieve an energy resolution of 0.35eV at zero energy-loss. The instrument is shielded within a metal box to reduce acoustic noise. A SDD EDX detector is installed to perform STEM-EDX analysis for heavy elements at atomic resolution. This microscope is capable of high-resolution imaging and microscopy functions including: HAADF-STEM, LAADF-STEM, BF-STEM, STEM-EELS, and STEM-EDX. The Hitachi STEM is particularly good at resolving the chemical and electronic information of materials at the deep nanoscale.

FEI Titan 80-300, a dedicated Environmental Transmission Electron Microscope (E-TEM)

Contact: Dmitri Zakharov

This instrument is the first 80-300kV field-emission environmental transmission electron microscope to be installed in the US with an objective-lens aberration corrector. It has a spatial resolution of 0.08nm in the high-resolution phase contrast mode, and can achieve this resolution at unusually high pressures due to the differential pumping apertures and custom pumping arrangement that is incorporated with the system. The maximum gas pressure for the environmental-cell is about 20mbar for N₂, with other maximum pressures dependent on the atomic weight of the gas. As a result, this instrument is uniquely well-suited to image the fundamental mechanisms of catalysis and catalyzed nanostructure growth. The instrument also has scanning transmission imaging (STEM), magnetic imaging, and chemical analysis capabilities. In addition, a Lorentz lens and a bi-prism allows imaging electrostatic and magnetic potentials or fields in materials. The FEI Titan is also equipped with an energy dispersive x-ray spectrometer and an electron energy-loss image filter spectrometer. A mass-flow controlled catalytic reaction system capable of providing controlled pressures of gas mixtures will be installed in the near future.

FEI Talos 200x an operando Scanning Transmission Electron Microscope

Contact: Kim Kisslinger

The FEI Talos F200X is a high-resolution analytical scanning/transmission electron microscope (S/TEM) that is routinely operated at 200 keV. This microscope is equipped with an X-FEG electron source module that gives a source brightness four times that of a Schottky FEG emitter. This high source brightness enables near diffraction limited imaging and dramatically improves the spectroscopic performance. In addition to the extra-bright gun, it combines outstanding high-resolution scanning/transmission electron microscope and TEM imaging with a four-quadrant 0.9-sr energy dispersive X-ray spectrometer (EDS) for elemental and compositional mapping. Talos F200X allows for the fastest and most precise EDS analysis in all dimensions, along with HRTEM imaging with fast navigation for in-situ microscopy. The instrument is custom designed to have an objective-area pressure interlock and differential pumping capabilities close to the gun to protect the field emitter from any gas leakage event. Due to this protection feature, gas- and liquid-cell operando holders can be readily used in this system to study reaction dynamics under liquid and gas environments.