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Results for “Electron Probe Microanalysis”

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At least 847 records · Page 47Linked to original sources
PubMed1987

Advanced mercuric iodide detectors for X-ray microanalysis.

We first present a brief tutorial on Mercuric Iodide (HgI2) detectors and the intimately related topic of near-room temperature ultralow noise preamplifiers. This provides both a physical basis and technological perspective for the topics to follow. We next describe recent advances in HgI2 applications to x-ray microanalysis, including a space probe Scanning Electron Microscope (SEM), Synchrotron x-ray detectors, and energy dispersive detector arrays. As a result of this work, individual detectors can now operate stably for long periods in vacuum, detect soft x-rays to the oxygen K edge at 523 eV, or count at rates exceeding 2x10(5)/sec. The detector packages are small, lightweight, and use low power. Preliminary HgI2 detector arrays of 10 elements with 500eV resolution have also been constructed and operate stably. Finally, we discuss expected advances in HgI2 array technology, including improved resolution, vacuum operation, and the development of soft x-ray transparent encapsulants. Array capabilities include: large active areas, high (parallel) count rate capability and spatial sensitivity. We then consider areas of x-ray microanalysis where the application of such arrays would be advantageous, particularly including elemental microanalysis, via x-ray fluorescence spectroscopy, in both SEMs and in scanning x-ray microscopes. The necessity of high count rate capability as spatial resolution increases is given particular attention in this connection. Finally, we consider the possibility of Extended X-ray Absorption Fine Structure (EXAFS) studies on square micron sized areas, using detector arrays.

Electron Probe Microanalysis↗
PubMed1985

Development of otoconia in the embryonic chick (Gallus domesticus).

In the chick (Gallus domesticus) embryo, otoconium formation started first over the macula sacculi around the 4th day of incubation, and a day later over the macula utriculi. It was determined that each otoconium formed as a result of the segmentation of the immature otolithic membrane, and that the calcium responsible for otoconium calcification was incorporated into the organic matrix of each otoconium in the form of small electron-dense granules (20-150 nm in diameter). The presence of calcium in these granules was confirmed by histochemical staining with osmic-potassium pyroantimonate, by EDTA chelation, and by X-ray microanalysis under the electron microscope.

Animals↗
PubMed2006

Fast element mapping of titanium wear around implants of different surface structures.

The effect of unintended titanium release around oral implants remains a biological concern. The current study was undertaken to evaluate a new detection system of element mapping in biological probes. A new scanning electron microscopy-energy dispersive spectroscopy detection method was used to map the features of titanium contamination in peri-implant bone around implants with different surface structures. The amount of titanium wear was highest adjacent to titanium-plasma-sprayed surfaces, followed by sandblastered large grid acid-etched and smooth surfaces. A high sensitivity of titanium detection over large areas of bone tissue was observed. A high spatial resolution of titanium wear particles (20 nm) could be reached and correlated to the ultrastructural morphological features of peri-implant tissue. Cells adjacent to titanium wear revealed no signs of morphological alterations on a nanoscale level at early periods of implant/bone interaction. The new technique may serve as a fast and effective tool to evaluate titanium release effects in biological probes.

Acid Etching, Dental↗
PubMed1987

The use of extraction replicas in scanning electron microscopy for the elemental analysis of marginal seals.

Elemental analysis of marginal seal material on 20 bulk samples of occlusally restored teeth have shown that, generally, more elements were detected in the seal material analyzed on the bulk restoration or fractured tooth surfaces than when such material was extracted using a nitrocellulose replica prior to analysis. No mercury was detected in any of the extracted seal material and only three of the replica specimens contained silver. This implies that the technique of using extraction replicas to remove material from the amalgam-tooth interface for subsequent x-ray microanalysis can provide an accurate elemental composition. The details of fabrication and the advantages of using high resolution nitrocellulose replicas for extracting marginal seal material from teeth for subsequent x-ray microanalysis are described.

Dental Amalgam↗
PubMed1991

Loss of grain boundary segregant during ion milling.

It is shown that material segregated to grain boundaries can be lost during ion milling. This specimen preparation artifact has been studied in the case of bismuth in copper and has also been observed for phosphorus in stainless steel. The loss is associated with specimen heating during ion milling and can be alleviated by good clamping and cooling of the specimen during milling. Specimen heating permits grain boundary diffusion of the segregating element to the specimen surfaces with subsequent loss of segregant from the specimen by evaporation or sputtering during ion milling. Loss of bismuth during in situ heating to 200-300 degrees C is demonstrated. Therefore, care must be taken in specimen preparation for analytical electron microscopy measurement of such segregation. Similar effects may occur during ion milling of other materials, especially those where low thermal conductivity will result in high beam heating. In these cases, care must be taken to avoid loss of segregant during specimen preparation. Additional tests showed that no significant loss of segregant was observed during X-ray microanalysis, even at nominal room temperature and probe currents five-fold higher than that normally used for microanalysis.

Bismuth↗
PubMed1987

Role of scanning electron microscopy and x-ray microanalysis in the identification of urinary crystals.

Urinary crystals can be identified by using analytical electron microscopic techniques of scanning electron microscopy and energy dispersive x-ray microanalysis. Crystal habit can be recognised by scanning electron microscopy and their chemical nature by elemental analysis. With a conventional detector the lightest element that can routinely be detected is sodium, but with a windowless or thin window detector even carbon can be detected. Thus almost all the commonly occurring urinary crystals including uric acid can be analysed by energy dispersive x-ray microanalysis.

Calcium↗