FETEM – Transmission Electron Microscope of atomic resolution

• Description

The JEOL F200 is a transmission electron microscope that allows a great amount of applications. Thanks to its cutting-edge technology in the field of electron microscopy, the F200 is an ideal microscope for the characterization of samples from materials science as well as life sciences.

Its condenser system of 4 lenses provides a lot of flexibility to the illumination conditions; an independent control of the electron beam size, probe current and its convergence angle, optimizing the usage time for the equipment. This configuration also allows measurements at very low electron doses (e-/Å2s) for those samples sensitive to the electron beam.

Apart from the usual TEM mode, the F200 includes STEM detectors to acquire images while scanning the electron beam across the region-of-interest, reaching resolutions down to 1.4 Å. This detector configuration provides the technician/user the possibility to acquire images in bright field (BF), dark field (DF), annular bright field (ABF), annular dark field (ADF), high-angle annular dark field (HAADF) and from backscattered electrons, a range of image contrasts suitable for the observation of both light and heavy elements.

This microscope incorporates a high energy resolution EDX detector to perform elemental experiments at the nanometric as well as atomic level. Furthermore, its design enables the acquisition of tomographies with holders of high angular tilt (±80°) and make three-dimensional reconstructions of the elements present in the sample, enabling the reconstruction of any type of particle to evaluate its morphology down to the atomic resolution.

The FETEM is complemented with a CMOS-based Gatan OneView camera of 4096 by 4096 pixels to capture images and diffraction patterns. Its high quality allows the acquisition of atomic resolution images, and diffraction patterns with reflection intensities suitable for crystal structure determinations. The high recording speed (up to 320 fps) enables the possibility of in-situ experiments, capturing in real-time the evolution of the sample under different external stimuli (DENS holders are available for heating, biasing and liquid experiments). The OneView can be also used as a pixelated detector for the acquisition of 4D-STEM data (maps where each pixel corresponds to a diffraction pattern), which can result in maps that show the different crystallographic phases and/or orientations, mechanical strain, differential phase contrast (DPC) or even electric and magnetic fields.

• Technology

Software

• TEMography.
  Software package to automatize the tomographic data acquisition, its 3D reconstruction and its visualization.
• Gatan Microscopy Suite (v3).
  Control program for the Gatan OneView camera that allows data acquisition at frame rates up to 320 fps and its subsequent storage and processing. The in-situ package is available to record real-time videos.
• PyJEM.
  Scripting software for microscope and camera control to program functions adapted to the requirements or needs of a given experiment.
• STEMx. 
  Acquisition system for 4D-STEM data with the Gatan OneView camera for maps of crystallographic phases and/or orientations, mechanical strain, electric/magnetic fields and DPC.
• Fast-ADT.
  Software for the automated acquisition of 3D electron diffraction to characterize and determine crystal structures from different materials.

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• Applications

The versatility and flexibility of the F200 TEM allows a large list of applications where the microscope can be of great utility:

• Characterization of nanostructured materials:

• Nanoparticles, nanorods, nanosheets: Morphology studies (2D projections as well as tomographies). Size distributions. Atomic resolution images. Identification of crystalline facets and/or crystallographic growth directions. Core and shell distinction by high resolution images and EDX tomographies. Identification of the crystal structure.
• 2D materials like graphene or molybdenum disulphide: Visualization of atomic structure at low kV and low dose to avoid knock-on damage. Identification of defects.
• Samples prepared by FIB / semiconductor devices: Identification of the different parts of the sample and their sizes by TEM/STEM images. Distribution of the possible grains and their grain boundaries. Identification of structural defects. Maps of crystallographic phases and/or orientations, mechanical strain, electric and/or magnetic fields and EDX.

• Characterization of biological samples:

• Tissue, cellular and molecular studies at low electron doses to avoid the beam damage.
• Localization and distribution of proteins and enzymatic activities by measurements at high magnification and EDX maps.
• Detection and distribution of specific glucidic residues and cytochemical studies.

• In-situ experiments: 

• Heating or biasing: Monitorization of materials like alloys and metallic coatings to temperature variations at nanometric and atomic levels. Nanometric evaluation of electric devices like cathodes from all solid-state batteries by the application of different voltages. Real-time visualization of the evolution, growth, modification of the crystalline phase of crystalline solids or amorphization (reversible or irreversible) under temperature or electric voltage variations.
• Liquid: Measurements of particles or biological samples in their natural environment, avoiding fixation techniques if possible. Observation of in-situ growth of different materials under the electron beam.