Spatial resolving power

In the same way, spatial resolving power is a measure of the efficiency of distribution-analytical methods in micro- and surface analysis as well as scanning methods. From all the systematic representations of distribution-analytical problems given in Danzer et al. [1991], the mostly relevant are represented in Fig. 7.12. 

The spatial resolving power will be described for three concrete cases (i) Lateral resolving power characterizing fine scans as shown in Fig. 7.12b... 

Table 7.7. Spatial resolving power Rsmfice of selected analytical methods. For reasons of comparability an area of 1 mm2 has been taken in the case of 3-D SIMS a volume of v = 0.1 mm3 is taken as the basis... 

Spatial efficiency coefficient (RA spatial resolving power see Eqs. (9.36a-c), a number of spots needed to be investigated)... 

If the spatial resolving power has to be high, then the Raman radiation must be observed through microscope objectives (Fig. 3.5-10 b). Unfortunately, these objectives have a somewhat lower optical conductance than the regular sample arrangement (Schrader, 1990). As a result, the observed Raman spectrum is also considerably weaker. A microscope may be connected to the spectrometer by a mirror system or by optical fibers, as shown in Fig. 3.5-10 b. Optical fibers are e.specially useful for NIR FT Raman spectroscopy, because the transmission of the fibers may be at its maximum exactly in the range of a Raman spectrum excited by a Nd YAG laser (Fig. 3.3-5). 

The spatial resolving power is especially large, if the confocal technique is applied (Schrader et al., 1993, 1994). A focus of a laser beam is produced by a microscope objective of large numerical aperture at the spot of the sample to be investigated (Fig. 3.5-12). The radiation emerging from this spot is projected by the objective onto a diaphragm with a hole of the size of the projected laser focus. Only the radiation passing... 

The preliminary results show that is possible to use our camera as a bi-dimensional PSD with digital readout of the strips from a few keV up to about 100 keV, with a spatial resolution compatible with the geometrical pixel size (500 im), and a high spatial resolving power (E/AE 13 60 keV). Other tests are in progress for improving the evaluation of the spatial resolution and its dependence on the photon energy and to study the uniformity of the response across the whole active detector surface. 

Two alternative methods of Raman imaging via global illumination and via point illumination in combination with confocal light collection were applied to the study of heterogeneous polymer systems. The spectral and spatial resolving power of the different techniques was estimated experimentally. The influence of the depth resolution on the Raman image of a defined sample structure was demonstrated in a mathematical simulation. Data are given for PE, PS, polyacrylate, and epoxy resins. 23 refs. 

Even at the 300-nm spatial resolving power of the Raman microscope, CPO, EPR, and PP are highly blended and are not discernible as discrete pure component domains. Nevertheless, trends in the pure component distributions are observable. For example, PP distribution is less at the surface than the CPO and EPR, which are strongly colocalized near the air interface. Image analysis reveals that the highest concentration of CPO is within the first 20 fjim of the surface. However, some of the CPO penetrates deeper into the sample and forms irregularly dispersed domains. 

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