Electron microprobe line scan

Fig. 3.11. Temporally ( ) or spatially (/) dependent analytical measurements, e.g., a line scan of electron microprobe analysis represented in a three-dimensional (a) and quasi-three-dimensional way (b)... 

Microsegregation was studied by electron microprobe analysis of samples cooled at 0,5°C/s and quenched from just below the solidus temperature. Line scans were performed in selected areas of the specimens. Before analysis the samples were etched and the lines to be traversed were marked with microhardness indentations. Strongly etched specimens were repolished before measuring. Two lines were selected from different areas in each specimen, on the same principle as that for selecting lines for dendrite arm measurement. Consequently, in most cases secondary dendrite arms were crossed at right angles but some primary dendrites were intersected also. A typical example of a traverse for analysis is shown in figure 1.9. 

Fig. 73. Electron microprobe (EPMA) line time 5 min gas flow 210 mL/min at 530 Pa scans (x-ray intensity in arbitrary units, versus argon pressure, burning voltage 1 kV current beam location) of burning spots of jet-assisted 58 mA. The scanned line is highlighted in Crimm-type glow discharge, (a) 0.5 mm jets white in the left-hand photograph. (Reprinted and (b) 0.2 mm jets sample brass sputtering with permission from Ref. [238].)...

These two techniques demand fine spatial resolution which is achievable with AES but not with ESCA. In both cases, the compositional depth profile is then conveniently obtained using a narrow electron beam in a line scan instrument such as a scanning Auger microprobe, SAM [95]. 

Figure 21-17 illustrates the use of the electron microprobe for the analysis of an -cohenite (Fe,C) particle in a lunar rock. The data were obtained by a linear scan of the particle observed visually on the surface and by measurement of the intensity of the characteristic emission line for each of four elements. 

After drying in air the metal distribution was established using electron microprobe analysis. The scanning electron microscope used was a Jeol-35. A step size between 20 and 30 pm was applied. The metal distribution was determined by carrying out a scan along the shortest line through the centre of the catalyst body. 

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