Layers edge on

In many cases when the elastic properties of a material vary with depth, the most accurate way to study them is in cross-section. This has proved 

These values give an indication of the fractional variation of the optical refractive index and the Rayleigh velocity as a function of the dopant concentration. However, the relationship may not be linear over the range indicated (especially Ge02) and the original data should be consulted for accurate purposes (Jen etal. 1989). 

The specimen shown in Fig. 10.12 had been kept at 450°C in air for 500 hours after manufacture had been completed. In the first acoustic image (Fig. 10.12(a)), there is a layer thick surrounding the outer /3-SiC this 

The Rayleigh velocity of the fibres and the matrix were measured in this study, and had average values of 3074 ms 1 for the matrix (cf. the value for titanium in Table 6.3), 6610 m s 1 for the /3-SiC in the fibres (somewhat higher than the range of values for most other solids), and 2766 ms 1 in the carbon core. Such measurements played an important part in the interpretation of results in the very extensive study from which these pictures 

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Microspectroscopy applies the identification power of infrared spectroscopy to the microscopic realm. Contaminants on printed circuit boards, blemishes in coatings, and other production defects can be isolated in situ and analyzed (see Electronics, coatings). Analysis of flaws that develop during use illuminates the method of failure. Microscopic samples, such as particulates filtered from air, can be analyzed individually. The forensic applications are many paint chips, single fibers, explosive residues, and inks on currency can all be identified nondestmctively (see Forensic chemistry). The structures of layered materials, such as laminated polymer films, are studied via microspectroscopy by cross-sectioning the materials and examining the individual layers edge on (47). 

Figure 14 Part of the (11)- (p-chlorophenol) structure projected in the be plane, showing three parallel layers edge-on and with their hydrogen atoms omitted. The alternating handedness of adjacent layers is apparent.

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