Transmission Electron Microscopy

Characterisation Installation 4
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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.


WARNING: Access to CNRS temporarily not available, but the technique is available at the other sites

          provided at NFFA-Europe laboratories by:

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

Up to ~100nm thick samples

High vacuum @ sample level: 10-5Pa

Automated collection of tilt series (electron tomography) in TEM or STEM mode

Inspect 3D and Amira software for tomographic reconstruction



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 2k by 2k CCD camera from Gatan

EDXS detection on 50mm SSD from Oxford Instruments

Image resolution around 0.17nm (TEM) and 0.2nm (STEM)

Spectral resolution 130eV approx. on EDXS

TEM sample can be moved plus/minus 1mm in X and Y, and tilted plus minus 10 degrees in two axes (double tilt holder)

3mm standard TEM samples

Standard vacuum in the microscope column

Plasma cleaner to remove hyrdocarbons that cause contamination in the microscope

Image-processing programs and Image calculation programs available



TEM analysis


Beam Voltage: 200 kV  

2kx2k GATAN 895 USC 4000

X-Ray detector EDS Oxford Instruments X-max

0.18 nm at 200 kV

No STEM capabilities

Single tilt holder

High vacuum

Ultramicrotomy for polymers and life science samples



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)



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



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.

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

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

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

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.