Sample preparation mounting

The procedures for sample preparation, mounting and cleaning have been described previously (26). Briefly, the rhodium single crystal rod was oriented to 1/2° using X-ray back reflection and a 1 mm. thick disc was cut by spark erosion. After mechanical... 

Sample preparation methods vary widely. The very first procedure for characterizing any material simply is to look at it using a low-power stereomicroscope often, a material can be characterized or a problem solved at this stage. If examination at this level does not produce an answer, it usually si ests what needs to be done next go to higher magnification mount for FTIR, XRD, or EDS section isolate contaminants and so forth. 

SPMs are simpler to operate than electron microscopes. Because the instruments can operate under ambient conditions, the set-up time can be a matter of minutes. Sample preparation is minimal. SFM does not require a conducting path, so samples can be mounted with double-stick tape. STM can use a sample holder with conducting clips, similar to that used for SEM. An image can be acquired in less than a minute in fact, movies of ten fiames per second have been demonstrated. ... 

This technique can be applied to samples prepared for study by scanning electron microscopy (SEM). When subject to impact by electrons, atoms emit characteristic X-ray line spectra, which are almost completely independent of the physical or chemical state of the specimen (Reed, 1973). To analyse samples, they are prepared as required for SEM, that is they are mounted on an appropriate holder, sputter coated to provide an electrically conductive surface, generally using gold, and then examined under high vacuum. The electron beam is focussed to impinge upon a selected spot on the surface of the specimen and the resulting X-ray spectrum is analysed. 

Because of the complexity of sample preparation, backscatter measurement geometry (see Fig. 3.19) is the choice for an in situ planetary Mossbauer instrument [36, 47 9]. No sample preparation is required, because the instmment is simply presented to the sample for analysis. On MER, the MIMOS II SH is mounted on a robotic arm that places it in physical contact with the analysis target (e.g., rock or soil) [36, 37]. 

Fig. 8.28 External view of the MIMOS II sensor head without contact plate assembly (left) MIMOS II sensor head mounted on the robotic arm (IDD) of the Mars Exploration Rover. The IDD also carries the a-Particle-X-ray Spectrometer APXS, also from Mainz, Germany, for elemental analysis, the Microscope Imager MI for high resolution microscopic pictures ( 30 pm per pixel), and the RAT for sample preparation (brushing grinding drilling (< 1 cm depth)). Picture taken at Kennedy-Space-Center KSC, Florida, USA...

We use commercial Ti02 crystals (Pi-Kent) cut and polished to within 0.3° of the (110) face and we prepare them further with cycles of Ar + bombardment and U H V annealing to approximately 950-1100 K, typically 5-10 min for each cycle. The samples are mounted onto tantalum back-plates via strips of tantalum spot-welded to the back-plate. Annealing is performed by high-energy electron bombardment of the back-plate from a hot filament. Temperatures are measured from optical pyrometers (Minolta) focused on the back-plate. The temperatures are not measured directly from the samples because they are translucent and get darker with each sputter/anneal cycle. 

A section of the epoxy sample, approximately 2cmx2cm, was removed from the bulk and mounted onto the XPS sample stage. The sample was mounted with the "titanium" side facing down, by way of double-sided tape. Thus, the "composite side" was analyzed. The composite tube was prepared similarly and the sampling area was selected so as not to include the first 5 mm or beyond 30 mm from the end of the tube. The regions in the first 5 mm and the area beyond 30 mm from the end were classified as the non-bonded regions. Thus, the "epoxy side" or outer surface side of the composite tube was analyzed in the "bonded region". 

In all microscopic methods, sample preparation is key. Powder particles are normally dispersed in a mounting medium on a glass slide. Allen [7] has recommended that the particles not be mixed using glass rods or metal spatulas, as this may lead to fracturing a small camel-hair brush is preferable. A variety of mounting fluids with different viscosities and refractive indices are available a more viscous fluid may be preferred to minimize Brownian motion of the particles. Care must be taken, however, that the refractive indices of sample and fluid do not coincide, as this will make the particles invisible. Selection of the appropriate mounting medium will also depend on the solubility of the analyte [9]. After the sample is well dispersed in the fluid, a cover slip is placed on top... 

Once the tissue slice is mounted on the sample plate, the sample preparation becomes the critical step in the process. In general, two strategies are employed to apply matrix... 

Bulk spectroscopic techniques such as x-ray fluorescence and optical and infrared spectroscopies involve minimal sample preparation beyond cutting and mounting the sample. These are discussed in Section 9.2.1. Spectroscopic techniques such as wavelength dispersive spectroscopy (WDS) and energy dispersive spectroscopy (EDS) are performed inside the SEM and TEM during microscopic analysis. Therefore, the sample preparation concerns there are identical to those for SEM and TEM sample preparation as covered in Section 9.3. Some special requirements are to be met for surface spectroscopic techniques because of the vulnerability of this region. These are outlined in Section 9.5. 

In summary, sample preparation is an essential part of microscopy and there are many techniques (and variations) that can be used. The approaches very commonly used to prepare specimens for analysis are as follows The sample needs to be cut to size using one of the slicing methods outlined. The cut sample is either set in a mold or mounted externally on a polishing mount. This step is followed by a series of coarser to finer grinding on SiC grit... 

The sample preparation procedures for the direct analysis of small molecules in tissue have been described by several papers [120-124], Tissues (brain, heart, lung, kidney, liver, etc.), were immediately frozen and stored at -80 °C after harvest. The frozen tissues were subsequently cut into serial 10-20 pm thick section which was typically prepared by cryosectioning on a microtome at a temperature of -20 °C. The adjacent sections were gently mounted onto a conductive surface, MALDI imaging target plate or glass slides. These plates were desiccated under low vacuum for a short period of time until dry, then robotically or manually coated with the... 

Measuring Raman spectra of polymorphs requires little or no sample preparation. Spectra can be measured from single crystals and from powders. Moreover, samples can be contained in glass capillaries or mounted on a goniometer. As mentioned earlier, fiber optics can be used to interface the instrument with the samples. Thus the measurements are straightforward and easy to perform, whereas the analyses produce information on structures and spectral fingerprints for straightforward identifications. 

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