Direct imaging instrument

The second type of SIMS Instrument the direct Imaging type Is based on the design of Castaing and Slodzlan (IQ). In the direct Imaging Instrument an area 1 to 300 pm In diameter Is bombarded by the primary Ions. The secondary Ions are extracted by an electrostatic Immersion lens which maintains a point to... 

Fig. 3.19. Basic set-up of a direct imaging magnetic sector instrument. The stigmatic secondary ion optics consists of an electrostatic analyzer (ESA) and a magnet sector field.

Common to all available instruments are small particle numbers, which result in poor statistics. Thus recent developments have yielded a combination of powerful dry and wet dispersion with high-speed image capturing. Particle numbers up to 10 can now be acquired in a few minutes. Size and shape analysis is available at low statistical errors [W. Witt, U. Kohler, and J. List, Direct Imaging of Very Fast Particles Opens the Application of the Powerful (Dry) Dispersion for Size and Shape Characterization, PARTEC 2004, NUrnberg]. 

Three types of instrumentation exist for dynamic SIMS non-imaging ion probes, direct-imaging ion microanalysers and scanning ion microprobes-micro-scopes. Non-imaging ion probes are often an accessory of Auger electron spectroscopy (AES), electron spectroscopy for chemical applications (ESCA), or electron microscopy systems and allow a point analysis. Imaging equipment allows a point-to-point analysis of the surface with a primary beam of size 10—300 pm (microanalysers) or below 10 pm (microprobes-microscopes). 

There is another interest in nanoscale science and technology, i.e., the observation of nanometer-size structures with scanning probe microscopies (SPMs). Among the SPMs, several kinds of methods to directly image magnetic structures have been developed. The instrument most widely used now is magnetic force microscopy (MFM), which has a high spatial resolution on a 10-nm scale. 

By means of the atomic force microscope (AFM), a recent innovative instruments, the first direct images of the periodic array of hexagonal cavities for the basal planes of clay minerals was opportunely reported by Hartman et al. 

Texture studies on wires and plates are very important. Initial information can be acquired from transmission and reflection patterns recorded with a flat-film camera (see Fig. 1.5). The type and degree of texture can be determined more or less exactly, depending on the object of investigation and the type of instrument used. One of the best-developed instruments is the Liicke texture goniometer [125]. With this apparatus, the distribution of given net planes can be directly imaged in a pole figure. 

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