Transmission Electron Microscopy

Structural & Morphology Characterization (Electron and ion beam technologies)

TEM and STEM are related techniques which can be considered as the most powerful tools to characterise nanomaterials and indispensable for nanotechnology. In both the cases, high energy electrons, incident on ultra-thin samples, allow for image resolutions that are on the order of 1-2 Angstroms. The electron beam travels through the specimen and, depending on the density of the material present, some of the electrons are scattered, while unscattered electrons hit a fluorescent screen at the bottom of the microscope, giving rise to a "shadow image" of the specimen with its different parts displayed in varied darkness according to their density. In the STEM mode, electrons pass through the specimen, but, as in scanning electron microscopy, the electron optics focus the beam into a narrow spot which is scanned over the sample in a raster. The rastering of the beam across the sample makes these microscopes suitable for analysis techniques such as mapping by energy dispersive X-ray (EDX) spectroscopy, electron energy loss spectroscopy (EELS) and annular dark field imaging (ADF). These signals can be obtained simultaneously, allowing direct correlation of image and quantitative data. By using a STEM and a high-angle detector, it is possible to form atomic resolution images where the contrast is directly related to the atomic number.

Traditionally, TEM/STEM have been mainly applied for imaging, diffraction, and chemical analysis of solid materials. For biological samples, cell structure and morphology is commonly determined whilst the localization of antigens or other specific components within cells is readily undertaken using specialised preparative techniques and, when required specific TEM cooling, holder.

A TEM can also be used to do Electron Tomography, which allows obtaining detailed three dimensional (3D) structural characterisation of 3D objects. This is accomplished by multiple views of the same specimen obtained by rotating the angle of the sample along an axis perpendicular to the beam. By taking multiple images of a single TEM sample at differing angles a set of images can be collected.

In the last few years, there has been a considerable revolution in electron microscopy with the arrival of aberration correctors for the objective lens with the consequent improvement in the attainable resolution limits. The obtainable resolution limit now lies at around 0,1 nm or better in both TEM and STEM, and the improved images from these aberration-corrected microscopes are opening up new avenues in the characterisation of materials.

Sample preparation is the most crucial part in TEM experiments. High quality TEM specimens have a thickness that is comparable to the mean free path of the electrons that travel through the samples, which may be only a few tens of nanometres. Preparation of TEM specimens is specific to the material under analysis and the desired information to obtain from the specimen. Sample preparation laboratories are equipped with the basic tools (diamond saw, polisher, dimpler, electropolisher, ultrasonic cutter, precision ion polishing system, gentle mill, plasma cleaner) commonly used in conventional chemical and mechanical thinning procedures.

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          provided at NFFA-Europe laboratories by:
CNR-IOM (TS)
Italy
CNR-DSCTM
Italy
CEA/LETI
France
C2N-CNRS
France
CSIC-ICMAB
Spain
JCNS @MLZ
Germany
ICN2
Spain
INL
Portugal
JRC - ISPRA
Italy
KIT
Germany
LUND + MAX IV
Sweden
UAB
Spain
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          provided by:
EURONANOLAB
France
CNR-IOM (TS)
Italy
JEOL JEM 2010F UHR TEM/STEM
Transmission Electron Microscopy/Scanning Transmission Electron Microscopy
High-brightness thermally assisted field emission gun (FEG), spherical aberration coefficient of the objective lens: (0.47±0.01) mm
Beam voltage: 80-200 kV
STEM attachment High-angle annular dark field (HAADF) for Z-contrast imaging
≤0.13 nm probe size 0.11 nm phase contrast 0.123 nm HAADF/STEM
Constant temperature with a drift rate < 0.1°C/min, with low noise and minimal turbulence
EDX with ultra-thin window for light elements sensitivity (Z > 5)
CSIC-ICMAB
Spain
TEM - JEOL JEM 1210
Image mode: information about the size, morphology, homogeneity and microstructure of the samples. Diffraction mode: determination of the cell parameters, space group and superstructures, incommensurate modulations
Thermionic emission from a tungsten filament
Accelerating voltage: 120 KV
CCD camera ORIUS 831 SC 600 GATAN, suitable for imaging and electron diffraction registration
Point to point resolution of 3.2 Å
Particulate materials (powders, nanoparticles, nanowires..)
Standard single tilt holder and analytical specimen holder of double tilt (Tilt X=± 60o, Tilt Y=± 30o), GATAN 646 model, that allows exploring large volumes of reciprocal space by electron diffraction
JCNS @MLZ
Germany
TEM JEOL JEM-2200F
Soft Matter investigation by room temperature TEM as well as Cryo-TEM on frozen thin specimen in liquid state and solid thin sections of polymers. Detailed information is available at https://mlz-garching.de/tem Real space investigations performed to extract information about shape, size and size distribution of particles, their self-assembly and aggregation.
Field Emission Gun
200 kV acceleration voltage
Image recording on 2k by 2k CMOS Camera from Tietz Video Imaging and Processing System (TVIPS)
Image resolution around 0.17 nm in theory, but 2 nm for room-temperature TEM and 5 nm for Cryo-TEM due to the actual (temporary) environment
Standard vacuum (10-6 Pa range) inside the instrument column
Specimen preparation devices for soft matter: - Leica EM GP grid plunger for thin film of aqueous and organic solvent solution onto Cryogen (liquefied Ethane) - Leica SCD050 for glow discharge to prepare the grid prior to freeze-plunging - Leica UC-7/FC-7 Cryo-ultramicrotome using glass and diamond knife to perform ca. 100 nm thin cryo-sectioning on bulk polymer or resin embedded block specimen. - Leica Freeze Fracture and Etching BAF060 to produce replicas from solution samples.
3 mm holey carbon coated cupper grids. 3 mm standard cupper grids. Gold grids on demand. Thin liquid specimen, thin (ca. 100 nm) sections, eventually sample in powder state
TEM sample can be moved plus/minus 1 mm in X and Y and tilted plus/minus 23° in X direction (Goniometer) 4 positions RT-TEM holder and 2 positions Cryo-TEM holder
ICN2
Spain
TEM – FEI Tecnai G2 F20 HRTEM
High resolution (S)TEM imaging, chemical composition analysis and electron tomography
ZrO2/W (100) Schottky field emission gun
Beam voltages: 80kV, 120kV and 200kV
High resolution transmission electron microscopy (HRTEM) High resolution scanning transmission electron microscopy (HRSTEM) with bright filed (BF), dark filed (DF) and high angle annular dark field (HAADF) modes Energy Dispersive X-ray Spectroscopy (EDX) Electron Energy Loss Spectroscopy (EELS) Energy filtered TEM (EFTEM)
Point resolution: 0.24 nm Information limit: 0.102 nm
High vacuum @ sample level: 10-5Pa
Up to ~100nm thick samples
Automated collection of tilt series (electron tomography) in TEM or STEM mode Inspect 3D and Amira software for tomographic reconstruction
LUND + MAX IV
Sweden
JEOL 3000F TEM
Imaging and analysis at the nano-level via conventional transmission electron microscopy (TEM), high resolution TEM, scanning TEM, and EDXS (energy dispersive Xray spectroscopy)
Field emission gun
300kV accelerating voltage
Image recording on 4k by 2.7k Orius camera from Gatan. EDXS detection on 80mm SSD from Oxford Instruments.
Image resolution around 0.17nm (TEM) and 0.2nm (STEM). Note neither image nor probe is aberration-corrected.
Standard vacuum in the microscope column
Plasma cleaner to remove hydrocarbons that cause contamination in the microscope. Image-processing programs and Image calculation programs available.
3mm standard TEM samples
TEM sample can be moved plus/minus 1mm in X and Y, and tilted plus minus 10 degrees in two axes (double tilt holder)
Spectral resolution 130eV approx. on EDXS
UAB
Spain
TEM JEOL 2011
TEM analysis
LaB6
Beam Voltage: 200 kV
2kx2k GATAN 895 USC 4000 X-Ray detector EDS Oxford Instruments X-max
0.18 nm at 200 kV
High vacuum
Ultramicrotomy for polymers and life science samples
No STEM capabilities Single tilt holder
CIC biomaGUNE
Spain
Multimode V from Bruker
CIC biomaGUNE
Spain
TEM – JEOL JEM-2100F UHR
CIC biomaGUNE
Spain
TEM – JEOL JEM-2100F UHR
JRC - ISPRA
Italy
Transmission electron microscopy (TEM)
Transmission electron microscopy (TEM) is a microscopy technique able to analyse ultrathin specimens through which an electron beam is transmitted forming an image. This microscope is used to characterise nanomaterials size and morphology and, if combined with energy dispersive x-ray spectroscopy (EDX), elemental composition. TEM is widely used to study cellular ultrastructure and to identify nanomaterials in complex matrices.