THE EFFECT OF SHAPE AND SIZE ON THE ELECTRONIC-PROPERTIES OF ULTRAFINE METALLIC PARTICLES

The subject of ultrafine metallic particles is treated with emphasis on energy level statistics. The energy level statistics so far proposed are reviewed based on the effect of shape of particles. The deviation of the nature of the chemical bond and that of magnetic properties in small size systems from those of bulk is described. The relevant electronic properties are expressed by formulae that incorporate the effect of shape in addition to size. New and old experiments including NMR Knight shift and static magnetic susceptibility are analyzed by means of the proposed formulae. The shape of particles is discussed in connection with the preparation methods. A concept of “the degree of metallicity” is introduced to characterize the statistics of level spacing fluctuation of small metal particles. A number of electronic properties of small size materials are also explained in terms of their sizes. The systems examined are small particles and conjugated chain compounds. The concept of zero-dimensionality is proposed and it is correlated with certain conservation laws such as topological invariance (conservation of shape) and as a conservation of the number of spins (parity of electrons). © 1990, Taylor & Francis Group, LLC. All rights reserved.