NCEM Capabilities & Tools
NCEM operates an array of state-of-the art electron microscopes, offering a wide range of capabilities for materials characterization at high resolution. Several of these instruments, most notably the TEAM suite of microscopes, are unique and of world class. Others are at the state of the art, or offer forefront capabilities and techniques such as in-situ nanoindentation, spin-polarized low-energy microscopy, or tomography.
TEAM I is a double-aberration-corrected (scanning) transmission electron microscope (S/TEM) capable of producing images with 50 pm resolution. The basic instrument is a modified FEI Titan 80-300 TEM equipped with a special high-brightness Schottky-field emission electron source, a source monochromator, a high-resolution GIF Tridiem energy-filter, and CEOS hexapole-type spherical aberration correctors and a chromatic aberration corrector. The illumination aberration corrector corrects coherent axial aberrations up to 4th order, as well as 5th order spherical aberration and six-fold astigmatism. The imaging aberration corrector fully corrects for coherent axial aberrations up to 3rd order and partially compensates for 4th and 5th order aberrations. The microscope has two 2048×2048 slow-scan CCD cameras; one is bottom mounted and one is the GIF camera. The microscope is fitted with the piezo-electric TEAM stage (alpha<±180°, beta<±180°). The microscope can be operated either at 80 kV or 300 kV in the following modes:
- High-resolution TEM with acquisitions suitable for focal-series reconstructions
- High-resolution STEM (BF and HAADF detectors)
- Energy filtered imaging and high-resolution electron energy-loss spectroscopy
- Three-dimensional electron tomography in both STEM amd TEM modes
The Transmission Electron Aberration-corrected Microscope (TEAM) project was a multi-facility development project to integrate the latest advancements in electron optics, detectors, sample stages, and computational techniques into a suite of instruments freely available to the worldwide scientific community. TEAM 0.5 is a double-aberration-corrected (scanning) transmission electron microscope (STEM/TEM) that was the first of two instruments acquired by the National Center for Electron Microscopy in the culmination of this multinational endeavor. TEAM 0.5 was the first electron microscope in the world to demonstrate 50pm resolution in both TEM and STEM modes and 0.1eV energy resolution. In addition to world-class resolution, the exceptional sensitivity of TEAM 0.5 enables the detection of not only atomic columns, but in many cases single atoms. Access to this state-of-the-art facility is provided through a competitive proposal system judged by a panel of external reviewers on the basis of scientific merit.
The TEAM 0.5 instrument platform is a modified FEI Titan 80-300 microscope equipped with a high- brightness Schottky-field emission electron source, a gun monochromator, a high-resolution GIF Tridiem energy-filter, and two CEOS hexapole-type spherical aberration correctors. The illumination aberration corrector corrects coherent axial aberrations up to 4th order, as well as 5th order spherical aberration and six-fold astigmatism. The imaging aberration corrector fully corrects for coherent axial aberrations up to 3rd order and partially compensates for 4th and 5th order aberrations. The microscope has two 2048×2048 slow-scan CCD cameras; one mounted below the projection chamber and the other at the exit of the GIF. A double-tilt holder (alpha<±30°, beta<±15°) and a dedicated single-tilt tomography holder (alpha<±75°) are available. The microscope can be operated either at 80 kV or 300 kV in the following modes:
- High-resolution TEM with acquisitions suitable for focal-series reconstructions and low dose-rate imaging (also available at 50kV and 20 kV)
- High-resolution STEM (HAADF detector) also suitable for depth sectioning
- STEM-EELS measurements of local composition and bonding
- Energy filtered imaging and high-resolution electron energy-loss spectroscopy
- Monochromated low-loss EELS for measurement of local band gap and plasmonics
- Electron TEM/STEM tomography
The 200kV Zeiss monochromated LIBRA 200MC is designed to produce high contrast imaging for TEM and STEM and either convergent beam or parallel beam diffraction using Koehler illumination. In addition, the incorporation of a monochromator into the field emission gun enables energy resolution of ~0.15eV for electron energy loss spectroscopy. The dedicated in-column Omega Filter can be used for spectroscopic analysis, energy-filtered imaging, and energy-filtered diffraction with a 2048×2048 CCD camera The high tilt capability of the stage and ~10mm pole piece accepts various types of both tomography and cryo holders. The Orius camera facilitates video capture at 30fps. This microscope is optimized for soft materials applications that require either the high contrast imaging performance or analytical methods such as EFTEM and STEM.
The One-Angstrom Microscope (OÅM) is a mid-voltage transmission electron microscope (TEM) capable of producing images with sub-angstrom resolution. The basic instrument is a modified Philips CM300FEG/UT, a TEM with a field-emission electron source and an ultra-twin objective lens with low spherical aberration (Cs = 0.60 mm) and a point-to-point resolution of 1.7Å. Special, highly stable power supplies for the objective lens and for high-voltage power produce an information limit of 0.8Å. A 2048×2048-pixel charge-coupled device (CCD) camera digitally records images up to a maximum magnification of 38Mx. The microscope can operate at an acceleration voltage of either 300kV or 150 kV and can produce aberration-corrected exit wave images with 0.8Å resolution. The OÅM can operate in any of the following modes:
- Focal series restoration from lattice images, using focal-series reconstruction
- Electron holography
- Annular dark field TEM imaging
- Energy filtered imaging and spectroscopy
The 200kV FEI monochromated F20 UT Tecnai is designed to produce optimum high resolution performance in both TEM and STEM. In addition, the incorporation of a monochromator into the gun permits electron energy loss spectroscopy to be performed with an energy resolution of ~0.15eV. This microscope features a 2048×2048 CCD camera positioned after the Gatan Imaging Filter (GIF) that can be used for both dedicated spectroscopic analysis and energy-filtered imaging. This microscope is optimized for materials applications that require either the highest resolution STEM performance (imaging and spectroscopy) or correlated imaging and analytical methods (TEM and STEM).
The Spin-Polarized Low-Energy Electron Microscope (SPLEEM) is a unique low-voltage electron microscope for the study of surfaces and interfaces. The instrument is very sensitive to structural and electronic properties of sample surfaces and is well-suited for in-situ research within a highly controlled sample environment. Spin-polarization of the electron beam permits imaging of magnetic domain microstructure.
This custom-built equipment is designed to be easily adaptable to enable various types of experiments and exploration of new ideas. During imaging, it is usually possible to provide the following: clean vacuum (low 10-11 torr); variable sample temperature (~130 K to over 2500 K); in-situ deposition of films or multilayers (most metals, some oxides), co-deposition of several components. Within limits, magnetic field at the sample can be adjusted. Samples can be introduced through a loadlock and can be cleaned within the same UHV system (low-energy sputtering with noble- or reactive gases, heating, in-situ cleaving…). Auger-electron spectroscopy and conventional low-energy electron diffraction are available.
During imaging, it is usually possible to provide:
- Clean vacuum (low 10-11 torr).
- Variable sample temperature (~130 K to over 2500 K).
- In-situ deposition of film or multilayers (most metals, some oxides, co-deposition of several components,…).
- Within limits, magnetic field at the sample can be adjusted.
- Samples can be introduced through a loadlock and can be cleaned within the same UHV system (low-energy sputtering with noble- or reactive gases, heating, in-situ cleaving…). Auger-electron spectroscopy and conventional low-energy electron diffraction are available.
The 300 kV JEOL 3010 offers greater specimen penetration than 200kV instruments, with good spatial resolution and probe forming capabilities. A flexible condenser system permits CBED, LACBED, and imaging with hollow cone and Koehler illumination. In addition to a Gatan Multiscan camera, a Gatan Orius 833is available for acquiring diffractions patterns without a beam stop and for recording experiments at video rates. Specific capabilities include: imaging at 2.1Å and ±40° tilt during simultaneous heating; high-resolution imaging at 1.7 Å and ±10° tilt during simultaneous heating; and high magnification Lorentz and Foucault imaging of magnetic samples. Various heating, cryo, mechanical testing and electrical biasing holders are available. The 3010 is the microscope most used for static liquid cell experiments.
Microscopists planning to use a heating specimen holder should consult the heating holder guidelines.
Heating holder guidelines
If you plan to use heating holders for in-situ experiments, we require your careful review and compliance with the following guidelines.
1. Include in your proposal target temperature and all phase diagrams of material with those of the tantalum furnaces and tantalum and/or molybdenum washers. Eutectic melting or bonding to the furnace body can occur at much lower temperatures than expected.
2. Holders are individually marked with the maximum temperature displayed on the specimen rod. Do not exceed this marked maximum temperature. It is easy to overshoot target temperature, so approach with caution.
3. Pre-schedule time for technical training and assistance by NCEM staff, especially if you are an infrequent or first-time user.
4. Heating holders are extremely delicate and must be loaded and unloaded with great care. Please seek help if you are unclear about any steps in the procedure.
5. The water recirculator must always be turned on for target temperatures above 500C.
6. If specimens are not self supporting, copper grids are generally adequate to 500C. For target temperatures above 500C, molybdenum grids are required. Gatan G-1 high temperature epoxy remains intact at temperatures in excess of 1000C.
7. The tantalum hex screw ($200 ea.) and tantalum washers ($20 ea.) are expensive to replace. If you drop these accessories on the floor, please find them immediately or ask someone for help in locating them.
8. Use of heating holders for vacuum heat treatment of specimens is strictly forbidden.
The FEI Strata 235 dual beam Focused Ion Beam (FIB) is used for TEM sample preparation, taking advantage of the focused Ga+ ion beam for site-selective material removal and the field emission scanning electron microscope (SEM) column for imaging. The SEM can be used for chemical analysis through electron dispersive spectroscopy or combined with an electron backscatter detector for orientation imaging analysis. Pt or SiO2 can be deposited for sample protection before thinning or for lift-out procedures with an Omniprobe system.
Capabilities of the NCEM FIB
Imaging: Secondary electrons or ions produced by the incoming electron or Ga+ beams are collected to form an image of the sample.
Milling/Etching: The FIB can locally etch the sample surface with submicron precision. Many variables and material properties affect the sputtering rate of a sample. These include beam current, sample density, sample atomic mass, and incoming ion mass. The main ion species used at NCEM is Ga+, with an additional low-energy Ar+ ion source available on the FIB or using the Fischionne NanoMill after FIB preparation. Additionally, iodine gas-assisted etching is available. When a gas is introduced near the surface of the sample during milling, the sputtering yield can increase depending on the chemistry between the gas and the sample. This results in less redeposition and more efficient milling.
Deposition: Conductive or insulator material can also be deposited with the aid of a gas in close proximity to the sample surface. Our system is equiped to deposit either metal (Pt) or insulator (SiO2). These materials can be deposited with either the ion or electron beam.
Microchemical analysis: Element mapping and energy dispersive X-ray spectrometry (EDS) are available on the NCEM FIB system.
Orientaion imaging: Advanced diffraction and crystallographic analysis capabilites, based on electron backscatter diffraction (EBSD), are an integral part of our FIB system.
Nanoscale Manipulation: Capable of nanoscale manipulation of TEM membranes or other samples with an Omniprobe micromanipulators.
The Philips CM200/FEG is used for standard analysis of the physical and chemical microstructure of materials. In addition to high resolution imaging, the machine is capable of analytical electron microscopy, including spatially resolved compositional analysis by X-ray emission spectroscopy (Z > 5), local electronic structure measurements by electron energy-loss spectroscopy (Z > 2), convergent beam electron diffraction for three-dimensional structure information, and energy-filtered imaging at the nanometer scale.
The FEI TitanX 60-300 microscope at NCEM is used for hardware, software, and technique development; it is available for user experiments during the remainder of the time. The TitanX is equipped to do fast energy dispersive X-ray mapping (EDS), high-angle STEM or TEM tomography, and in-situ heating/biasing experiments, as well as STEM/TEM. The ability to switch between 60, 80, 120, 200, and 300kV during one TEM session gives the user flexibility to optimize experimental conditions – balancing sample damage, spatial resolution, and signal-to-noise.
Images are acquired with a Gatan UltraScan 1000 (2k x 2k) Camera for high-resolution TEM, a Gatan Orius 830 (2k x 2k) for diffraction and movies (30 frames per second), or a HAADF detector for STEM. The Bruker windowless EDS detector with a solid angle of 0.7 steradians enables high count rates with minimal dead time. The ~5 mm pole gap of the FEI Super-twin objective lens is compatible with a variety of holders including a FEI EDS double-tilt holder, a Hummingbird tomography holder (alpha > +/- 70 degrees), Gatan 652 heating holder, and Protochips single and double tilt heating and biasing holders. Novel experimental techniques such as EDS with tomography, fluctuation microscopy, off-axis holography, and ALCHEMI (Atom Location by Channeling Enhanced Microanalysis) are being implemented on the TitanX.
The sample preparation facilities consist of four task-specific labs. The equipment resources, technologies and technique development, support a wide range of user needs. Stringent emphasis on sample quality is paramount to the imaging and analytical capabilities at NCEM.
houses a variety of grinding and polishing equipment for bulk material removal and geometrically precise polishing techniques
Ion beam Lab
offers a diverse collection of ion beam equipment for final milling and cleaning methods
supports electropolishing applications, chemical etching and heavy metal staining experiments
available to use at ambient and cryo-temperatures to gather electron transparent sections of a wide range of materials
- A general microscopy analysis and simulation package for OSX, written by former NCEM staffer Roar Kilaas.
- Can perform exit wave reconstruction, symmetry analysis, peak position measurements, geometric phase analysis and many more analysis methods.
- A general TEM image processing software provided by Gatan Inc.
- Various plugins available, including geometric phase analysis (GPA) for measuring strain in micrographs.
- Analysis software for STEM data provided by FEI.
Custom Analysis Code
- MATLAB Multislice Simulations
- Custom software routines for simulating images and diffraction patterns in TEM and STEM using a large number of scripts developed by Colin.
- Methods are given in Earl Kirkland’s textbook “Advanced Computing in Electron Microscopy,” second edition.
- Can be used to simulate virtually any scale of problem and vary any structural, chemical or optical parameter.
- IDL 3D Tomographic Reconstruction
- A 3D reconstruction algorithm and GUI developed by Peter.
- MATLAB Focal Series Reconstruction
- Code for reconstructing HRTEM exit wave phase with high accuracy, written by Colin.
- EMD Format and EMDviewer
- An open-source data format for microscopy data of any type, having an arbitrary number of data dimensions.
- Useful for visualization of extremely large experimental and simulated datasets.
- Can also be used to render movie frame images for use with FFMPEG.
- Can be downloaded for free here.