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Imaging and Microscopy Facility

Imaging and Microscopy Facility

The Imaging and Microscopy Facility (IMF) at UC Merced hosts optical, scanning and transmission electron microscopes, an X-ray diffractometer and equipment for preparing specimens for examination. IMF serves campus researchers in the physical sciences, biological sciences and engineering. It has a particular focus on nanotechnology. The facility offers students and researchers a range of materials characterization techniques, including advanced imaging, elemental analysis and structure determination. Our objective is to provide high-end, state-of-the-art instrumentation to campus members at a modest cost. We can provide training, technical and scientific support, teaching support, outreach support and assistance in preparing research proposals that require the services of our facility or that focus on electron microscopy and X-ray diffraction.

The facility is composed of one XRD, two microscope rooms and a large common area for light microscopy and sample preparation. In one of the microscope rooms is a FEI Quanta 200 environmental scanning electron microscope (ESEM) with a tungsten filament and EDAX Genesis energy-dispersive X-ray spectrometer 30mm2 detector with 132 eV resolution. The microscope has 4 nm spatial resolution and can detect characteristic X-rays down to and including beryllium, although sensitivity is limited for light elements. It can operate in the low vacuum range (10-3 to 0.8 Torr) and in environmental mode (0.1 to 40 Torr). In the environmental mode, it is possible to examine samples up to 100 percent relative humidity. Combining this with its other capabilities makes this a very versatile instrument. The EDAX Genesis software allows the user to collect spectra and elemental maps in both manual and automated modes. With this instrument, it is possible to view and perform X-ray analysis on nonconducting samples or “wet samples” without having to coat or dry.

The second microscope room features a JEOL JEM-2011 transmission electron microscope with LaB6 filament, Gatan GIF camera with 1.6 eV energy resolution, an EDAX XM 2 energy-dispersive X-ray spectrometer 30mm2 detector with 132 eV resolution, high angular angle dark-field (HAADF) detector, single, double tilt holders and cryo-transfer holder/stage. This instrument is capable of 2.4 Å point-to-point image resolution and 1.4 Å lattice fringe resolution. The Gatan GIF provides for the collection of electron-energy loss spectra and maps, in either nanoprobe (10 nm) or TEM mode. Electron energy-loss spectroscopy can be used for many purposes. It is very sensitive to light elements and complements another TEM technique (energy dispersive X-ray spectroscopy) that is most commonly used for heavier elements. It also can be used to determine plasmon energy, band gap, coordination, oxidation state and many other material characteristics at a spatial resolution of about 10 nm in the nanoprobe mode. The cryo-transfer holder is used in low temperature (0oC – -196oC) microscopy and is very useful for reducing damage rates, minimizing carbon contamination in soft materials or viewing frozen hydrated biological samples.

We have purchased a PANalytical X’Pert PRO Theta/Theta Powder X-Ray Diffraction System with X’Celerator Detector and a 15-position sample changer for high speed, high resolution phase analysis and XML-based software for data collection and data evaluation. The XRD has a solid-state X-ray generator (max. 60 kV, 50 mA); sealed Co X-ray tube (long-fine focal spot); theta-theta goniometer (accuracy +/- 0.0025°, step resolution 0.0001°, 2-theta measuring range 0-167°, scan speed 0.001-1.3° per second); solar slits; incident and detector anti-scatter slits. Included is a temperature-controlled, inert gas sample chamber attachment with goniometer adapter, temperature controller and liquid N2 delivery system (Anton-Paar TTK450). This chamber attachment operates from –193°C (liquid N2) to +450°C, with the sample held in a vacuum, air or inert-gas environment. It will support current research related to environmental studies that involve air-sensitive samples and oxidation kinetics and allow for cooling and heating experiments to moderate temperatures, which will support current materials and chemistry work.

The facility has a small laser cutter for plastic and wood.

Transmission electron microscopy sample preparation methods available include a wide variety of different techniques including negative staining, shadowing (unidirectional and rotary), epoxy resin embedding and ultra-thin sectioning of embedded materials. A cryo-ultramicrotome is available for thin sectioning of frozen material. For scanning electron microscopy, air-, critical point- or freeze-drying and sputter coating, carbon coating and thermal evaporation are available. For harder samples, the facility has saws and polishers.

IMF is a model facility to use for further development and testing of the NCK tool at the later stages of the project (Phase V) when our systems are more refined.