Transmission Electron Microscope (TEM)
Jeol 2000FXII (Jeol Ltd.,
The Jeol 2000FXII Transmission Electron Microscope has the capability of running at voltages up to 200kV and produces good resolution digital images. This is a high resolution instrument for TEM imaging, Scanning Transmission Electron Microscopy (STEM) and electron diffraction.
Transmission Electron Microscopy is a microscopy technique whereby a beam of electrons is transmitted through an ultrathin specimen, interacting with the specimen as it passes through it. An image is formed from the electrons transmitted through the specimen, magnified and focused by an objective lens. The image appears on a fluorescent imaging screen, plus a monitor, and can be recorded by a CCD camera.
The TEM is used in both materials science/metallurgy and the biological sciences. In both cases the specimens must be very thin and able to withstand the high vacuum present inside the instrument.
Scanning Electron Microscope (SEM)
Jeol Scanning Electron Microscope JSM-5510
(Jeol Ltd.,
The Jeol Scanning Electron Microscope (JSM 5510) operates at voltages up to 30kV, and has an Oxford Instruments Energy Dispersive X-Ray Spectroscopy detector attachment for elemental analysis.
The scanning electron microscope (SEM) images the sample surface by scanning it with a high-energy beam of electrons in a raster scan pattern. The beam of electrons strikes the surface of the specimen and interacts with the sample at or near its surface, producing signals that contain information about the sample. The types of signals generated by an SEM include secondary electrons, back scattered electrons, characteristic x-rays and light. Electronic devices are used to detect and amplify the secondary electrons and display them as an image which is digitally captured and displayed on a computer monitor. The SEM can produce very high-resolution images of a sample surface, revealing details less than 5 nm in size. SEM micrographs have a very large depth of focus yielding a characteristic three-dimensional appearance useful for understanding the surface structure of a sample.
The SEM in the EM Facility is currently used to study samples from a variety of projects, from many different disciplines, including materials science, food science, biological sciences and geology. In all cases specimens must be dry, conductive and able to withstand the high vacuum present inside the instrument.
Energy Dispersive X-ray Spectroscopy
An INCA Energy Dispersive X-ray Spectroscopy Detector (Oxford Instruments, Buckinghamshire, UK) is installed on the SEM.
Energy Dispersive X-ray Spectroscopy (EDS or EDX) is an analytical technique used for the elemental analysis or chemical characterization of a sample.
X-rays that are characteristic of an element's unique atomic structure are emitted when the electron beam removes an inner shell electron from the sample, causing a higher energy electron to fill the shell and give off energy. These characteristic x-rays are used to identify the elemental composition of the sample.
