INSTRUMENTS

FEI Titan3 G2 60-300 dual aberration-corrected TEM/STEM

Image of Titan (S)TEM

The University of Hawai‘i’s Titan monochromated and dual aberration-corrected (scanning) transmission electron microscope.

Image of Titan (S)TEM

The Titan (S)TEM behind Hope Ishii (AEMC Director), Matthieu DuBarry (HNEI) and Karim Zaghib (HydroQuebec).

Image of Titan (S)TEM

AEMC researcher John Bradley oversees a field emission tip change on the Titan (S)TEM.

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Overview

The Titan (scanning) transmission electron microscope or (S)TEM operates at accelerating voltages between 60 and 300 keV, and electrons are passed through the sample.  Dual spherical aberration (Cs) correctors provide a sub-Ångstrom electron probe and sub-Ã…ngstrom imaging of thin specimens, typically only 20-120 nm in thickness.

Specimen petrography / texture / structure can be imaged directly using one of multiple brightfield and darkfield modes — with single-atomic-column resolution, if necessary.

Image HRTEM lattice fringe imaging

High resolution TEM lattice fringe image of stacking faults in pyroxene.

High angle annular dark field (HAADF) image

High angle annular dark field (HAADF) image of an inclusion in ancient chromite. (Rectangle indicates region in EDX maps below.) Image courtesy of Caroline Caplan.

Image of Titan (S)TEM

Nanodiffraction from a osbornite nanocrystal in a comet 81P/Wild 2 calcium aluminum inclusion returned by NASA’s Stardust mission.

 

Graph of nickel oxidation states

Nickel oxidation states in battery materials can be analyzed using electron energy loss spectroscopy (EELS).

Image of energy-dispersive X-ray spectroscopy (EDX) mapping

Energy-dispersive X-ray spectroscopy (EDX) mapping of the interface region between host chromite and inclusion in an ancient chromite grain. Images courtesy of Caroline Caplan.

Image of TEM heating holder

The furnace of the Gatan Model 652 double-tilt heating stage.

Crystal structure can be investigated by collecting either selected area or nanobeam electron diffraction patterns.

An optional monochromator can be used to narrow the energy bandwidth of electrons in the incident beam with 0.1-0.2 eV resolution. The monochromated electron beam, in conjunction with the Gatan Tridium energy-filter/electron spectrometer at the base of the microscope, enables electron energy loss spectroscopy (EELS). EELS is used to investigate atomic bonding environments, oxidation states, optical properties, molecular bonding and functional groups in organic materials and, in some samples, detection of liquids and gases.

Compositional mapping and spectroscopy approaching the atomic scale are possible using energy-dispersive X-ray spectroscopy (EDX), and compositional imaging can be obtained using energy-filtered transmission electron microscopy (EFTEM).

In-situ heating experiments are performed using a specialized hot stage sample holder. 

Capabilities and characteristics:

The UH Titan (S)TEM was funded by NASA’s Sample Return Laboratory Instrumentation and Data Analysis Program, which is now the Laboratory Analysis of Returned Samples Program.

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