Electron microscopy techniques

Learn more about transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), electron microprobe analysis and bio electron microscopy below.

TEM/STEM standard and aberration corrected

What is transmission electron microscopy (TEM)?

Transmission electron microscopy is a type of EM that transmits an electron beam through a specimen to form an image or diffraction pattern. In life science, TEM images are used to analyze the insides of cells, the organization of biological complexes and organisms, and reconstruct atomic protein structures. In material science, TEM images are used to determine material structures, image defects in crystals and composition, and structural variations across a material. TEM produces images with a magnification beyond 1,000,000x and a resolution power of from a few angstroms (10-10 m) to less than an angstrom.

What is high aberration-corrected transmission electron microscopy (ACTEM)?

Aberration-corrected transmission electron microscopy (ACTEM) is a subset of the TEMs which can achieve higher resolution than standard non-corrected TEM. ACTEMs are typically either image (TEM) or probe corrected (STEM). The correction is done using an advanced set of magnetic lenses to achieve subatomic resolution. One of the advantages of ACTEMs beyond the resolution is the ability to operate at lower acceleration voltages with a limited impact on the resolution.

What is scanning transmission electron microscopy (STEM)?

A scanning transmission electron microscope is a type of TEM that scans a sample like an SEM. STEM requires a thin sample lamella but can achieve the high resolution of TEM, allowing for atomic-resolution imaging. The broad beam of a TEM is focused on a nanoscale beam in STEM allowing nanoscale elemental analysis.

What are some applications of TEM?

Applications include imaging atomic structures, including defects; nanometer-scale selected-area diffraction; and 3D imaging.

What are some applications of TEM?

Applications include atomic imaging of individual atomic columns, elemental mapping, and elemental ID, including STEM with 0.8A spatial resolution with the aberration-corrected probe.

Standard TEM/STEM instruments

• Talos F200i
• Titan Krios (cryo TEM only)
• Talos L120C (Bio) 

Aberration corrected TEM/STEM instruments

• Nion UltraSTEM 100
• ARM200F (JEOL)
• Titan 300/80 (FEI)

The ASU Center for Aberration Corrected Electron Microscopy provides researchers with an unrivaled capability to understand the behavior of materials at the atomic level. Dedicated in February 2012, the center is considered one of the premier microscopy facilities in the United States. We designed the center’s building with exceptional stability in mind to achieve the highest level of visual and spectral resolution in electron microscopy. It has become the design standard for aberration-corrected microscopy.

Analytical TEM/STEM techniques: EELS and EDS

Electron Energy Loss Spectroscopy (EELS) and Energy Dispersive x-ray Spectroscopy (EDS) are two complementary techniques typically used to measure atomic composition. EELS can also provide additional bonding and oxidation state information.

EDS

• ARM200F (JEOL)
• ETEM Titan 300/80 (FEI)
• Talos F200i (TFS)

EELS

• ARM200F (JEOL)
• ETEM Titan 300/80 (FEI)
• UltraSTEM100 (NION)

Focused ion beam and TEM sample preparation

A focused ion beam (FIB) is a technique for site-specific milling and modification of a sample typically using a Gallium ions beam focused down to a few nanometers.

FIB applications: Dual beam, ion beam, and SEM for milling samples; TEM sample preparation; deposition; and imaging samples.

Sample preparation encompasses all the steps necessary for the modification of a sample into a specimen suitable for SEM or TEM analysis. Our sample preparation room is designed to process samples for both the SEM (cutting, grinding and polishing) and the TEM (cutting, grinding, dimpling, wedge polishing and ion milling). In addition, we can coat the sample with gold, gold/palladium or carbon to eliminate charging in the SEM and TEM.

• Focused Ion Beam – Helios 5 UX.
• Focused Ion Beam – Nova 200 NanoLab
• Bio EM Sample Preparation

Scanning electron microscopy

What is scanning electron microscopy?

Scanning electron microscopy is a type of electron microscopy that produces images by rastering a focused electron beam across the surface of a sample. This technique produces detailed images of a specimen’s surface. Its applications include surface topography and spatially resolved composition using Energy Dispersive Spectroscopy (EDS). SEM produces images with a magnification of 500,000x and a typical resolution power of a few nanometers.

• ESEM PrismaE (TFS)
• Electron Microprobe (JEOL)
• FIB/SEM – Helios 5 UX (FEI)
• FIB/SEM – Auriga (Zeiss)
• FIB/SEM – Nova 200 NanoLab (FEI)

What is the difference between TEM and SEM?

Transmission electron microscopy requires higher electron acceleration voltages and an electron transparent sample, the image is the result of the interaction of the electron as they travel through the sample. Scanning electron microscopy images the surface of the specimen, producing images of the sample surface. TEM has a higher resolution and magnification than SEM.

What is electron backscatter diffraction (EBSD)?

Electron Backscatter Diffraction (EBSD) is used to quantify a crystalline material’s microstructure. It is available on our Zeiss Auriga SEM/FIB instrument.

EBSD results from the interaction of an electron beam with a tilted crystalline sample. Diffracted electrons form a pattern characteristic of the crystal structure and orientation detected with a fluorescent screen. These diffraction patterns are then used to determine the crystal orientation, discriminate crystallographically different phases, characterize grain boundaries, and resolve local crystalline deformation.

The Oxford Symmetry S2 EBSD camera has a CMOS detector capable of analyzing over 3000 electron backscatter diffraction patterns per second. This accommodates the rapid analysis of crystallographic features, such as phase identification, the mapping of crystallographic orientations, or the analysis of strain and stress features in a crystalline material at a spatial resolution down to 30 nm.

Data acquisition is controlled with the Integrated Oxford AZtec software suite that uses crystallographic databases for phase definition. This application contains all tools necessary to collect and solve EBSD patterns. For data processing, the AZtec Crystal software can generate sophisticated maps, pole figures, and grain property analyses from EBSD data.

A Pace GIGA vibratory polisher equipped with a variety of sample holders and 60 nm colloidal silica solution is used to remove mechanical damage from the upper surface of samples to prepare them for EBSD analysis.

Applications

• Geology, mineralogy.
• Semiconductors and microelectronics.
• Metals, alloys, composites, ceramics.
• Energy generation and storage.

Key analytical advantages

• Rapid, non-destructive analysis of tens of nm to mm-size regions of interest.
• Simultaneous acquisition of EBSD and EDS data to enhance phase identification.
• Sophisticated software that improves data acquisition and data reduction.

Techniques

• Phase identification.
• Strain analysis.
• Grain size distribution.
• Grain orientation analysis.

Contact

Axel Wittmann
Associate Research Scientist
[email protected]
480-727-8732

What is electron microprobe analysis?

Electron microprobe analysis is the quantitative detection of the electron-bombardment-induced emission of characteristic X-rays. This allows for the rapid, nondestructive determination of the chemical composition of regions smaller than 1 µm in a planar, well-polished sample that is stable under high vacuum (elements B to U for the JXA-8530F).

The JEOL JXA-8530F electron microprobe is an electron microscope that has a nominal imaging resolution of 3 nm with six spectrometers for non-destructive X-ray microanalysis and imaging of solid samples up to 10 cm in size.

The Schottky field-emission electron gun yields probe diameters that are only 1/5 to 1/10 the size of those produced in conventional electron microprobe instruments with tungsten filament or LaB6 tips, allowing for sub-micron analytical spatial resolution. Even at low acceleration and large currents, small probe diameters are obtained that allow high X-ray spatial resolution.

The instrument has 5 wavelength-dispersive spectrometers (WDS) that permit the measurement of elements from B through U, and is set up for conventional microanalysis as well as trace-element analysis. In addition, this instrument is equipped with an energy-dispersive spectrometer, which is capable of X-ray count rates in excess of 200k cps and has high-speed X-ray mapping and quantitative microanalytical capabilities that rival the WDS. It is also equipped with a panchromatic cathodoluminescence system that allows the detection of cathodoluminescence in the wavelength range between 200‒900 nm. For instrument control, we can utilize the customized JEOL system software and the PC-based Probe for Windows software.

Applications

• Mineralogy
• Geology
• Meteorites
• Semiconductors
• Metals
• Catalyzers
  

Key analytical advantages

• 3 nm secondary electron resolution.
• Large crystal spectrometers for high detection sensitivity for trace element concentrations.
• Increased count rate without sacrificing energy resolution and P/B ratio.
• High accuracy of quantitative analysis.
• High resolving power (resolution) for adjacent x-rays.
• 2 WDS spectrometers dedicated to the quantitative analysis of light elements (B to O).
• Dual TMP system for clean sample environment.
• Combined WDS/EDS.

Techniques

• Quantitative WDS of elements from B to U.
• Semi-quantitative EDS of elements from Be to U.
• Panchromatic CL imaging.
• BSE imaging.
• SE imaging.
• X-ray intensity mapping.

Contact

Axel Wittmann
Associate Research Scientist
[email protected]
480-727-8732

What is life science/bio electron microscopy?

Life science electron microscopy is a subset of electron microscopy focussing on biological samples, typically working with cryogenically frozen samples or resin embedded samples to render them vacuum compatible.

The Eyring Materials Center has a range of capabilities for life science and biomolecular electron microscopy applications:

• Titan Krios (FEI)
• Talos L120C TEM (TFS)
• Bio EM Sample prep