The principles and characteristics of a field ion microscope, a field emission micros-cope and an atom-probe field ion microscope are described. The resolving power of the field ion microscope is demonstrated by imaging the geometrical arrangments of individual atoms at the W-Ga, W-In and W-Sn interfaces. The observed results indicate that the Ga, In and Sn atoms in contact with four W atoms, which occupy W lattice sites, form a pseudomorphic monolayer and they are strongly bound to the W surface. A field ion microscope can be operated as a field emission microscope. The field emission microscopic observation has revealed that the work function takes its maximum value when the W surface is covered with the pseudomorphic monolayers of Ga, In and Sn. The applicability and the limitation for the field ion microscopy are discussed in comparision with the other surface research techniques.

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Diffraction studies on lattice vibration of fine particles of size less than a few hund-red angstroms in diameter are recently developed. The experimental method on the basis of the diffraction theory and the results in X-ray diffraction are described in detail. From the X-ray diffraction experiment on the temperature dependence of the integrated intensity in the Debye-Scherrer rings, the X-ray Debye temperature Θ_M 156 K has been obtained for the fine particles of silver, whose size was about 150 Å in diameter. The Debye temperature of the fine silver particles is much lower than that of the bulk silver crystal, i. e. Θ_M=212 K. This fact leads to the conclusion that the softening of lattice vibration is observed in the fine silver particles.

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