Optimized for lateral resolution and sensitivity, the NanoSIMS is a pure ion Microprobe (scanned focused ion beam) and has no ion microscope mode (transport of a stigmatic, magnified mass filtered ion image) as on the CAMECA IMS analyzers. One of the characteristics of the NanoSIMS is to work in high mass resolution: by design, there is no low mass resolution mode on the NanoSIMS, even when removing all apertures. In addition, the analyzer transmission is maintained very high (see plot above), even when increasing the Mass Resolution. This is the result of: - a very high, normal extraction field allowing a very early secondary ion focusing, - a limited field of view together with a dynamic emittance matching, - a careful transport and rectangular shaping of the secondary beam resulting in the use of small slit compared to the magnet size, reducing aberrations, - the correction of the second order mass spectrometer optical aberrations. |