ABSTRACT
To characterise a microstructure it is necessary to perturb the material by interacting in some way with it. Indeed in order to see a surface it is necessary to bombard that surface with photons of wavelengths within the visible range and this in itself may alter the material. A typical example of damage caused by photons is the response of a photographic film. To achieve higher resolution and thereby magnification it is possible to use, for example, a scanning electron microscope where the photon source is replaced with electrons with an energy in the region of 10 to 30 keV. These are more damaging than photons since they penetrate a considerable distance on the atomic scale into the material. Many modern analytical instruments require high spatial resolution, while at the same time needing high sensitivity for the detection of elements within the material. Often this involves bombarding the surface with ionised atoms of high energy which, although extremely damaging, provides microstructural information that outweighs this disadvantage.
