Transmission electron microscopy current instruments

The transmission electron microscopy was done with a 100-kV accelerating potential (Hitachi 600). Powder samples were dispersed onto a carbon film on a Cu grid for TEM examination. The surface analysis techniques used, XPS and SIMS, were described earlier (7). X-ray photoelectron spectroscopy was done with a Du Pont 650 instrument and Mg K radiation (10 kV and 30 mA). The samples were held in a cup for XPS analysis. Secondary ion mass spectrometry and depth profiling was done with a modified 3M instrument that was equipped with an Extranuclear quadrupole mass spectrometer and used 2-kV Ne ions at a current density of 0.5 /zA/cm2. A low-energy electron flood gun was employed for charge compensation on these insulating samples. The secondary ions were detected at 90° from the primary ion direction. The powder was pressed into In foil for the SIMS work. 

In developing and ophmizing new ES materials and components (electrode materials, electrolytes, and current collectors) based on their structures, morphologies, and performance, physical characterization using sophisticated instrument methods serves as the necessary approach. These instrumental methods are scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (RS), Fourier transform infrared spectroscopy (FTIR), and the Brunauer-Emmett-Teller (BET) technique. 

Analysis of individual catalyst particles less than IMm in size requires an analytical tool that focuses electrons to a small probe on the specimen. Analytical electron microscopy is usually performed with either a dedicated scanning transmission electron microscope (STEM) or a conventional transmission electron microscope (TEM) with a STEM attachment. These instruments produce 1 to 50nm diameter electron probes that can be scanned across a thin specimen to form an image or stopped on an image feature to perform an analysis. In most cases, an electron beam current of about 1 nanoampere is required to produce an analytical signal in a reasonable time. 

Electron microscopy in both its transmission and scanning inodes has been the technique of choice for the vast majority of literature studies, particularly structural studies [see compilations in 17,18,19]. Other reviews and texts which cover the techniques of microscopy used in Food Science include Aguilera and Stanley [2] and the earlier work of Vaughan [25]. In addition to covering many of the current uses of microscopy in Food Science the former book [2] covers the histoiy of food microscopy and an introduction to the major microscopy instruments. It also presents the information in such a manner as to demonstrate how microscopy can be a useful tool in food science for both the product developer and the basic food scientist. 

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