Microprobe multipliers

Another large instrument with emphasis on high transmission at high resolution for isotopic measurements in geological applications is the IMS 1270 [60]. This instrument is similar in design to the IMS-3f and other Cameca f-series instruments but is much larger. It operates in either microprobe or microscope mode. Four auxiliary detector assemblies, containing an electron multiplier or Faraday cup plus the central beam primary detector, provide simultaneous detection of five isotopes. 

Generally, SIMS instruments are operated in two modes microscope mode and microprobe mode. A defocused primary ion beam ( 5—300 pm) is used for investigating a large surface in the microscope mode. The secondary ions are then transmitted to the mass spectrometer and generally detected by imaging. In the microprobe mode, a focused primary ion beam (< 10 pm) is used to investigate a small portion of the surface and detected usually in an electron multiplier. 

Figure 19 Specific area of the D band approximated by the area of the D peak over sum of the areas of the D and G peaks, multiplied by 100, versus the in-plane crystallite size of La in angstroms. Points are for anthracene, thin and thick C films, and the Tuinstra and Koenig correlation for comparison [55]. (Reproduced from American Mineralogist, 78, Wopenka, B., et al., Structural characterization of kerogens to granulite-facies graphite Applicability of Raman microprobe spectroscopy, pp. 533-557. Copyright 1993, with permission from American Mineralogical Society.)...

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