Nano-fabrications are now available for us to produce well-defined nano-structures showing quantum effects, quantized electron conductance at point contact, of phase interference of electron waves at quantum wires, and single electron tunneling at nano-capacitors. It seems near that we can fabricate even such nano-structures that Professor L.Feynman had described in his book “miniaturization”: the smallest memory unit(nano-particle), which contains 5x5x5 atoms. Such nano-particles are expected to have physical and chemical properties depending on their surface nature, since they have rather large volume of surface atoms compared with that of the core atoms. The surface atoms of such nano-particles might be reconstructed to a structure different from their bulk crystal structure, as well the surfaces of silicon and GaAs are reconstructed. It is, therefore, interesting to fablicate such nano-particles and to study their structures.

To study structure and properties of nano-particle surfaces, we developed a UHV high-resolution electron microscope equipped with a field-emission gun (UHV-FE-HR TEM: revised version of JEOL 2000V) at our ERATO project, as shown in fig. 1.