Light emission with a blackbody-like spectrum was observed during current flow through atomic-size metallic contacts formed in the scanning tunneling microscope. Within the contact, the electron temperature rises above the lattice temperature as electron–phonon energy transfer vanishes. Electron temperatures of up to 9000 K were deduced from optical spectroscopy of stable contacts. An important consequence of greatly reduced electron energy losses is that these atomic-size metal contacts have maximum current densities of ∼1015 A m−2, several orders of magnitude greater than for macroscopic wires.
Interface segregation of boron at Si(111) surfaces has been studied at the atomic scale using a scanning tunnelling microscope (STM). During the segregation process (produced by thermal annealing), strong cooperative effects take place which cannot be explained by a simple nearest-neighbour pair interaction model. Although average surface concentrations of boron in the investigated temperature range could be calculated in terms of a Fowler's model, the comparison between STM and simulated images suggests that one must introduce longer-range interactions to describe the atomic-scale configurations.
In this paper, we propose an ultrasonic adaptive imaging method based on the phased-array technology and the synthetic focusing algorithm Total Focusing Method (TFM). The general principle is to image the surface by applying the TFM algorithm in a semi-infinite water medium. Then, the reconstructed surface is taken into account to make a second TFM image inside the component. In the surface reconstruction step, the TFM algorithm has been optimized to decrease computation time and to limit noise in water. In the second step, the ultrasonic paths through the reconstructed surface are calculated by the Fermat's principle and an iterative algorithm, and the classical TFM is applied to obtain an image inside the component. This paper presents several results of TFM imaging in components of different geometries, and a result obtained with a new technology of probes equipped with a flexible wedge filled with water (manufactured by Imasonic).
A Scanning Tunneling Microscope (STM) is used to excite individually localized plasmons in the tunneling gap between the probe tip and small supported silver particles. A blue shift of the maximum of the resonance when the thickness of the crystallite is decreased down to the nanometer is reported and explained in the framework of existing models.
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