Electron Microscope: Scanning, Environmental, Field Emission (FEI)
Quick Specs
- Operates in standard and environmental modes
- Equipped with EDX
- Equipped with scintillator-type, solid-state backscattered transmitted, and gaseous secondary electron detectors
EMSL's field-emission environmental scanning electron microscope (SEM) (FEI Model XL30) is a state-of-the-art instrument in which samples can be examined using a field-emission source electron beam both in standard (high-vacuum) SEM and environmental (wet) modes of operation. Equipped with a patented gaseous secondary electron detector, samples can be examined with up to 10 to 15 Torr of gas remaining in the chamber. Almost any sample of suitable size can be examined using this microscope without the use of additional specimen preparation procedures, which may introduce various artifacts. The microscope is also equipped with scintillator-type secondary electron detectors, solid-state backscattered and transmitted electron detectors, several different gaseous secondary electron detectors, and an energy-dispersive X-ray (EDX) spectrometer. The EDX spectrometer (EDAX Model 136-10) is outfitted with a Si(Li) detector with an active area of 30 mm2 and an ATW2 window that allows X-ray detection from elements higher than beryllium (Z>4).
High-Vacuum Mode
The main advantage of operating EMSL's field-emission environmental SEM in high-vacuum mode is its field-emission electron gun and advanced electron optics — which allows for very high-resolution/magnification to be achieved.
The instrument's conventional SEM/EDX mode is used for imaging and elemental analysis of conductive and coated samples. In addition, its computer-controlled SEM/EDX mode is used to analyze individual particles or micro-inclusions on a substrate. In this latter mode, a matrix of fields-of-view is placed over the sample area, with the area subsequently automatically inspected on a field-by-field basis. In each field-of-view, particles/micro-inclusions are recognized by an increase of the detector signal above a pre-selected threshold level. After recognizing the particles in a field-of-view, the program acquires an X-ray spectrum from each detected feature.
Environmental (Wet) Mode
By using cooling Peltier stage and high water vapor pressure in the sample chamber, researchers can achieve desirable levels of relative humidity (up to 100%) in the sample microenvironment. In these conditions, wet or hydrated samples (e.g., cells, plant samples, and tissue) will not become dry and introduce any artifacts. Dynamic experiments are also possible; for example, drying or crystallization processes can be examined in this mode. This mode is also very useful for imaging non-conductive specimens (e.g., paper, plastics, ceramics, fibers, fabrics). Using this instrument, water-sensitive non-conductive samples can be examined in an atmosphere of nitrogen or other gases.
This state-of the-art microscope has been mostly dedicated to detailed speciation of chemical and physical properties of atmospherically relevant aerosols. The data that can be provided by this technique offers a rich set of qualitative and quantitative information that is of primary importance to atmospheric processes involving particulate matter. The ability to observe phase, morphology, and compositional changes of the same single particles upon their reactions with trace atmospheric provides detailed information about the reaction mechanism.
Individuals who are experienced in the use of field-emission environmental SEMs may use this instrument; however, users are strongly recommended to take an SEM course for their own benefit. Basic training can be provided onsite.
All Related Publications Related Publications
- Hygroscopic Properties of CH3SO3Na, CH3SO3NH4, (CH3SO3)2Mg and (CH3SO3)2Ca Particles Studied by Micro-FTIR Spectroscopy.
- Antibody recognition force microscopy shows that outer membrane cytochromes OmcA and MtrC are expressed on the exterior surface of Shewanella oneidensis MR-1.
- Chemical Speciation of Sulfur in Marine Cloud Droplets and Particles: Analysis of Individual Particles from the Marine Boundary Layer Over the California Current.
- Kinetics of Heterogeneous Reaction of CaCO3 Particles with Gaseous HNO3 Over a Wide Range of Humidity.
- Hygroscopic Behavior of Substrate-Deposited Particles Studied by micro-FT-IR Spectroscopy and Complementary Methods of Particle Analysis.
