Contrast differences between scanning ion and scanning electron microscope images

The contrasts of scanning ion microscope images $(Ga+$ ion) at 30 keV are compared to those of scanning electron microscope images at 30 keV. Remarkable differences are observed in the surface sensitivity, crystal orientation, and atomic number effects of target material. The examples are shown by the secondary electron images and the origins of those differences are discussed on the basis of the different interactions of those particles with solid.