EMSL houses a state-of-the-art environmental transmission electron microscope (ETEM) and scanning transmission electron microscope (STEM). With the addition of a spherical aberration corrector for the probe forming lens and objective lens, the microscopes provide sub-Angstrom resolution for both STEM and TEM imaging modes. The microscopes can be operated with a voltage range of 80–300 kV and include a high-angle annular dark-field (HAADF) detector and CCD cameras for different imaging modes. The microscopes are fitted with energy dispersive x-ray spectroscopy and electron microscopy spectroscopy (EELS), which enable chemical composition analysis and electronic structural analysis for materials systems related to the Terrestrial-Atmospheric Processes Integrated Research Platform and the Biogeochemical Transformations Integrated Research Platform.
In contrast to the traditional operation of TEM under high vacuum, the ETEM at EMSL possesses a unique differential pumping aperture that allows for imaging at high temperatures and gas pressures up to 20 torr. The ETEM enables vital research across a range of scientific fields for observing atomic level processes as they happen. Attached to the microscopes are different probes, especially in situ probes, offering the unique capability of imaging of materials under in situ and operando conditions.
- Supporting the Terrestrial-Atmospheric Processes Integrated Research Platform, TEM-EDX-EELS can be used to investigate aerosol structure and chemical composition, including the detection of trace elemental contaminants and mapping the spatial distribution of contaminants.
- Supporting the Biogeochemical Transformations Integrated Research Platform, this system can be used to observe interfacial phenomena, including solid-liquid, solid-gas, and solid-solid interface structures, as well as biogeochemical sciences, including soft-hard material interfaces, bio-geochemical interface structures, and bio-mineralization structures.
- ETEM specifications:
- Beam energy 80–300 keV
- HRTEM point-to-point resolution: better than 0.1 nm
- STEM-HAADF image resolution: better than 0.136 nm
- Adjustable pressure around the sample: 10-5 to 20 Torr
- Temperature range around the sample: Cryogenic, and 25–1100°C
- Sample tilt range: -70° to 70°
- CCD camera 2k x 2k
- STEM specifications:
- Electron beam energy: 80–300 keV
- STEM HAADF point-to-point resolution at 300 kV: < 0.1 nm
- HRTEM phase contrast resolution (information limit at 300 kV): < 0.1 nm
- EELS energy resolution (with monochromator on): 0.15 eV
- High-tilt crystallographic and tomographic analysis
- Cryogenic imaging capability
- Sample tilt range: -70° to +70°
- CCD camera: 2k x 2k
Tips for success
- Appropriate preparation of the sample is critical for the success of using these resources. This typically involves the reduction of a “real” sample to a thin sample for electron transparency.
- Users will need to select their preferred imaging mode, voltage, beam current, and temperature to minimize potential beam effects.