I. Surface Structure
In order to understand interface structure an effort is being made to establish methods to form well-defined solid/liquid interfaces. This is being done by using many types of single-crystal surfaces along with both aqueous and nonaqueous solvents. Research is also focusing on new ways to make measurements and to control surfaces using in situ scanning probe microscopes, such as STM and AFM. In addition, the use of ultrahigh-vacuum surface-analysis techniques is being pursued. As part of this pursuit, special multi-chamber vacuum systems are being developed in which solid samples can be removed from a liquid and then analyzed without experiencing oxidation or contamination.

II. Surface Formation
Regarding interface formation, work is concentrating on the bond-formation reactions which occur at the solid/liquid interface. For example, the mechanisms by which metal and semiconductor surfaces are electrochemically formed and dissolved, thin-film crystal growth processes, as well as the adsorption and orientation of ions and molecules are being pursued. In addition, the formation of modified surfaces and new methods for making thin films using knowledge gained about reactions at the solid/liquid interface is being studied.

III. Surface Fabrication
Another area of concentration concerns interface fabrication, while concentrating on reactions that break bonds at the solid/liquid interface. The processes involved in chemical and electrochemical etching as well as in dissolving adsorbed molecular layers should hopefully be clarified. To this end, the electrochemical energy and optical energy necessary to control reactions at the solid/liquid interface are being applied. A search for technology to control metal and semiconductor surfaces at the atomic and molecular levels is also being conducted.

Application of UHV-EC to Analysis of Adlayers from Anions
We constructed two UHV-EC apparatus that are designed to process electrode surfaces in electrochemical environment and to transfer them into ultrahigh vacuum environment for examination by STM, LEED, AES, etc. which cannot be done in liquid phase. Figure 1 shows one of our UHV-EC machines. Combination of surface analysis tools in UHV and electrochemical STM led to high precision determination of adlattice structures of halogens and cyanide ions on gold and silver electrodes. Figure 2 shows continuous structure variation of iodine on Au(111) under potential control. In this figure, the LEED patterns correspond to the "reciprocal space image" of the in-situ STM images. The LEED patterns were utilized to determine lattice constants of iodine adlayer. Figure 3 shows a voltage-current curve, in-situ STM images and corresponding LEED patterns of gold-cyanide surface complex compound on Au(111).

Formation of Highly-ordered Monolayers of Organic Molecules on Electrode Surfaces
Our finding by in situ STM is that porphilins, crystal violet and other aromatic planer molecules form highly-ordered monolayers upon mobilization by iodine-passivated gold electrodes. The STM images resolve these organic molecules in detail. By this approach, many kinds of organic molecules and substrates have been tested. Figure 4 shows self-organized adlayers of porphyrin, crystal violet and PPV.

Formation of Chemisorptive Adlayers of Organic Molecules and Ions on Electrode Surfaces
In situ STM investigations revealed sell-ordered sulfate anions, cyanide anions, etc. on platinum and rhodium electrodes which exhibit relatively strong chemisorptivity. We found for the first time that water molecules and cations can be incorporated into these adlayers. (Figure 5) In situ STM also resolved internal structures of adsorbed benzene, quinones and other delivertives with high resolution (Figure 6).

Atomic-scale Observation of Semiconductor Electrodes and their Etching Processes
We successfully observed hydrogen-terminated surfaces of silicon and gallium arsenide single-crystalline electrodes in aqueous solutions (Figure 7). Furthermore, dynamic atomic-scale observations of these semiconductor surfaces during etching processes (Figure 8), which might lead to foundation of the basis of atomically flat substrate surfaces demanded in semiconductor industry of the next generation.

Observation of the Structures and Formation Processes of Electrodeposited Metals
The processes of formation of thin films of gold and silver were surveyed by in situ STM atomic resolution. Silver deposition on gold single-crystalline surfaces, in particular, the adlattice structures of Ag formed by underpotential deposition (UPD) depend on the composition of liquid phase. The multilayer deposit of Ag on the same surface is a high quality single-crystalline film. Figure 9 shows an in-situ STM image of the (4x4) structure of Ag on Au(111) formed by underpotential deposition in a perchlorate solution.

Preparation and Observation of Clean Surfaces of Base Metals
We devised methods of cleaning single-crystalline surfaces of the base metals such as nickel, cobalt, zinc, etc which were believed difficult to prepare . For the first time we observed the surfaces in action in acidic solutions by in situ STM. Furthermore, we observed the process of passivation of these surfaces by oxidation and the process of etching of atomically flat surfaces by presence of sulfur adatoms. Figure 10 shows time-sequential STM images of S/Ni(100) that exhibits catalytic atomic etching.

Observation of Adlayers on Electrodes in Non-aqueous Electrolytic Solutions
Attempts were made to purify polar non-aqueous solvents such as propylene carbonate and acetonitrile and to observe adsorption of iodine on gold and platinum electrodes by cyclic voltammogram and in situ STM. A different series of adlattice structures of iodine was found in propylene carbonate solutions by in situ STM. Figure 11 shows an image out of that series. This successful study opens an unprecedented approach of introducing a variety of non-aqueous solvents into nano-electrochemistry at the electrode surface.