Nanoscale Probes of the Solid--Liquid Interface deals with the use of the scanning tunnelling microscope (STM) and related instrumentation to examine the phenomena occurring at the interface between solid and liquid. Scanning probe microscopy (the collective term for such instruments as the STM, the atomic force microscope and related instrumentation) allows detailed, real space atomic or lattice scale insight into surface structures, information which is ideally correlated with surface reactivity. The use of SPM methods is not restricted to ultrahigh vacuum: the STM and AFM have been used on samples immersed in solution or in ambient air, thus permitting a study of environmental effects on surfaces. At the solid--liquid interface the reactivity derives precisely from the presence of the solution and, in many cases, the application of an external potential. Topics covered in the present volume include: the advantages of studying the solid--liquid interface and the obtaining of additional information from probe measurements; interrelationships between probe tip, the interface and the tunnelling process; STM measurements on semiconductor surfaces; the scanning electrochemical microscope, AFM and the solid--liquid interface; surface X-ray scattering; cluster formation on graphite electrodes; Cu deposition on Au surfaces; macroscopic events following Cu deposition; deposition of small metallic clusters on carbon; overpotential deposition of metals; underpotential deposition; STM on nanoscale ceramic superlattices; reconstruction events on Au(ijk) surfaces; Au surface reconstructions; friction force measurements on graphite steps under potential control; and the biocompatibility of materials.

This volume contains the proceedings of the NATO Advanced Research Workshop on "Atomic and Molecular Wires". It was sponsored by the Ministry of Scientific Affairs Division special program on Nanoscale Science with the support of the CNRS and the Max Planck Institute. Scientists working or interested in the properties of wires at a subnanoscale were brought together in Les Houches (France) from 6 to 10 May 1996. Subnanoscale wires can be fabricated either by surface physicists (atomic wires) or by synthetic chemists (molecular wires). Both communities present their foremost advances using, for example, STM to assemble atomic lines atom for atom, to fabricate a mask for such a line or using the wide range of chemical synthesis techniques to obtain long, rigid and conjugated oligomers. Interconnecting such tiny wires to sources (voltage, current) continues to demand a great technological effort. But nanolithography associated with microfabrication or STM are now clearly identified paths for measuring the electrical resistance of an atomic or a molecular wire. The first measurements have been reported on Xe , benzene, C ' di(phenylene-ethynylene) showing 2 60 the need for a deeper understanding of transport phenomena through subnanowires. Such transport phenomena like tunnel (off-resonance) transport and Coulomb blockade have been discussed by theorists with an emphasis on the exponential decrease of the tunnel current with the wire length versus the ballistic regime of transport.

In the last few years it was seen the emergence of various new quantum phenomena specifically related with electronic or optical confinement on a sub-wavelength-size. Fast developments simultaneously occurred in the field of Atomic Physics, notably through various regimes of Cavity Quantum Electrodynamics, and in Solid State Physics, with advances in Quantum Well technology and Nanooptoelectronics. Simultaneously, breakthroughs in Near-Field Optics provided new tools which should be widely applicable to these domains. However, the key concepts used to describe these new and partly related effects are often very different and specific of the Community involved in a given development. It has been the ambition of the Meeting held at "Centre de Physique des Houches" to give an opportunity to specialists of different Communities to deepen their understanding of advances more or less intimately related to their own field, while presenting the basic concepts of these different fields through pedagogical Introductions. The audience comprised advanced students, postdocs and senior scientists, with a balanced participation of Atomic Physicists and Solid State Physicists, and had a truly international character. The considerable efforts of the lecturers, in order to present exciting new results in a language accessible to the whole audience, were the essential ingredients to achieve successfully what was the main goal of this School.

The articles in this book have been selected from the lectures of a NATO Advanced Study Institute held at Bad Lauterberg (Germany) in August 1995. Internationally well-known researchers in the field of mesoscopic quantum physics provide insight into the fundamental physics underlying the mesoscopic transport phenomena in structured semiconductor inversion layers. In addition, some of the most recent achievements are reported in contributed papers. The aim of the volume is not to give an overview over the field. Instead, emphasis is on interaction and correlation phenomena that turn out to be of increasing importance for the understanding of the phenomena in the quantum Hall regime, and in the transport through quantum dots. The present status of the quantum Hall experiments and theory is reviewed. As a "key example" for non-Fermi liquid behavior the Luttinger liquid is introduced, including some of the most recent developments. It is not only of importance for the fractional quantum Hall effect, but also for the understanding of transport in quantum wires. Furthermore, the chaotic and the correlation aspects of the transport in quantum dot systems are described. The status of the experimental work in the area of persistent currents in semiconductor systems is outlined. The construction of one of the first single-electron transistors is reported. The theoretical approach to mesoscopic transport, presently a most active area, is treated, and some aspects of time-dependent transport phenomena are also discussed.

The first NATO Advanced Workshop on Quantum Tunneling of Magnetization (QTM) was organized and co-directed by Bernard Barbara, Leon Gunther, Nicolas Garcia, and Anthony Leggett and was held from June, 27 through July 1, 1994 in Grenoble and Chichilianne, France. These Proceedings include twenty-nine articles that represent the contributions of the participants in the Workshop. Quantum Tunneling of Magnetization is not only interesting for purely academic reasons. It was pointed out in the review article by L. Gunther in the December, 1990 issue of Physics World, that QTM may be destined to play a significant role within the next two decades in limiting the density of information storage in magnetic systems. Recent advances have indicated that this limitation may well be reached even earlier than first predicted. Furthermore, the number of people who have entered the field of study of QTM during these past few years has increased many fi)ld. The time was therefore opportune to hold a Workshop to bring together for the first time the leading researchers of QTM, both theoretical and experimental, so as to discuss the current status of the field. The most controversial issue at the time of the Workshop was how to establish r.eliable criteria for determining whether experimental results do indeed reveal manifestations of QTM. We believe that much progress was made at the Workshop on this issue.

An assessment of the recent achievements and relative strengths of two developing techniques for characterising surfaces at the nanometer scale: (i) local probe methods, including scanning tunnelling microscopy and its derivatives; and (ii) nanoscale photoemission and absorption spectroscopy for chemical analysis. The keynote lectures were delivered by some of the world's best scientists in the field and some of the topics covered include: (1) The possible application of STM in atomically resolved chemical analysis. (2) The principles of scanning force/friction and scanning near-field optical microscopes. (3) The scanning photoemission electron microscopes built at ELETTRA and SRRC, with a description of synchrotron radiation microscopy. (4) Recent progress in the development of spatially-resolved photoelectron microscopy, especially the use of zone plate photon optics. (5) The present status of non-scanning photoemission microscopy with slow electrons. (6) the BESSY 2 project for a non-scanning photoelectron microscope with electron optics. (7) Spatially-resolved in situ reaction studies of chemical waves and oscillatory phenomena with the UV photoemission microscope.

The study of sliding friction is one of the oldest problems in physics, and certainly one of the most important from a practical point of view. Low-friction surfaces are in increasingly high demand for high-tech components such as computer storage systems, miniature motors, and aerospace devices. It has been estimated that about 5% of the gross national product in the developed countries is "wasted" on friction and the related wear. In spite of this, remarkable little is understood about the fundamental, microscopic processes responsible for friction and wear. The topic of interfacial sliding has experienced a major burst of in terest and activity since 1987, much of which has developed quite independently and spontaneously. This volume contains contributions from leading scientists on fundamental aspects of sliding friction. Some problems considered are: What is the origin of stick-and-slip motion? What is the origin of the rapid processes taking place within a lub at low sliding velocities? On a metallic surface, is the rication layer electronic or phononic friction the dominating energy dissipation pro cess? What is the role (if any) of self-organized criticality in sliding friction? How thick is the water layer during sliding on ice and snow? These and other questions raised in this book are of course only part ly answered: the topic of sliding friction is still in an early state of development.

Proceedings of the NATO Advanced Study Institute, Erice, Sicily, Italy, June 19-29, 1995

Optics at the Nanometer Scale: Imaging and Storing with Photonic Near Fields deals with the fundamentals of and the latest developments and applications of near-field optical microscopy, giving basic accounts of how and under what circumstances superresolution beyond the half- wavelength Rayleigh limit is achieved. Interferometric and fluorescence techniques are also described, leading to molecular and even atomic resolution using light. The storage of optical information at this level of resolution is also addressed.