Microscopy techniques summarized

Fig. 5.97 The structures observed in uniaxially oriented LCP fibers, ribbons and films can be summarized by this structural model. The model defines the nature of the fibrillar textures into three categories based upon size macrofibrils, fibrils and microfibrils. In each case the sizes of structures have been determined from complementary microscopy techniques. (From Sawyer and Jaffe [353] reproduced with permission.)...

G. Cliff and G. W. Lorimer. J. Microscopy. 103, 203, 1975. This paper summarizes the Cliff-Lorimer analysis technique, but more complete reviews of the method may be found in References 1—4. 

Electron microscopy is a rather straightforward technique to determine the size and shape of supported particles [S. Amelinckx, D. van Dyck, J. van Landuyt and G. van Tendeloo, Handbook of Microscopy (1997), VCH, Weinheim]. Electrons have characteristic wavelengths of less than 1 A, and come close to monitoring atomic detail. Figure 4.13 summarizes what happens when a primary electron beam of energy between 100 and 400 keV hits a sample ... 

As can be seen in Fig. 3b, it is important to specify whether data are represented as a number distribution (obtained by a counting technique such as microscopy) or as a weight distribution (obtained by methods such as sieving), since the results will not be the same. Hatch and Choate [4] have developed equations for converting one type of diameter to another the relationships between them are summarized in Table 2. Note that caution should be exercised in using the Hatch-Choate conversions if the distributions do not closely fit the log-normal model. While this distribution is the most frequently used to describe pharmaceutical systems, other distribution functions have also been developed [2,5,6],... 

The most frequently applied analytical methods used for characterizing bulk and layered systems (wafers and layers for microelectronics see the example in the schematic on the right-hand side) are summarized in Figure 9.4. Besides mass spectrometric techniques there are a multitude of alternative powerful analytical techniques for characterizing such multi-layered systems. The analytical methods used for determining trace and ultratrace elements in, for example, high purity materials for microelectronic applications include AAS (atomic absorption spectrometry), XRF (X-ray fluorescence analysis), ICP-OES (optical emission spectroscopy with inductively coupled plasma), NAA (neutron activation analysis) and others. For the characterization of layered systems or for the determination of surface contamination, XPS (X-ray photon electron spectroscopy), SEM-EDX (secondary electron microscopy combined with energy disperse X-ray analysis) and... 

The previous section showed that interpretable HRTEM images are not obtained unless quite stringent experimental conditions are fulfilled. The important questions - What instrumentation does one need, and what does one actually do, to obtain an interpretable HRTEM image - have recently been considered by Veblen (1985a) who has described in some detail the experimental techniques that he has found essential for successful high-resolution microscopy. Because descriptions of tricks-of-the-trade are relatively rare in the literature, his main points are summarized in the following subsections. 

An interesting development of analytical electron microscopy, and a potentially very useful one for mineralogical research, has been made by Spence and Tafto (1982,1983). The technique, known as ALCHEMI (atom location by channeling enhanced microanalysis), is the electron analogue of an x-ray technique originally used by Batterman (1969). The theoretical basis of the technique was discussed in Chapter 4, but it is appropriate to summarize that discussion before considering the ALCHEMI technique in detail. 

---