Surface Science Tools Research Articles

Molecular manipulation using a tunnelling microscope.

In a very short time the scanning tunnelling microscope has become an important tool in surface science, and physics in general. Its primary use has been to obtain atomic-resolution images of surfaces, but recently, efforts have been made to use it to manipulate materials as well as image them. One may now reasonably ask if it is possible to move and alter matter predictably on an atomic scale. Here we report the accomplishment of the smallest yet, purposeful, spatially localized changes in matter, effected on a graphite surface. We believe that the changes result from the pinning of individual organic molecules to the graphite. The reverse manipulation, the removal of pinned molecules, has also been demonstrated. Finally, we have evidence that we can remove a portion of a pinned molecule, effectively performing transformations on single molecules using the tunnelling microscope.

ChemInform Abstract: SURFACE COMPOSITION AND CATALYSIS BY ALLOYS: ON THE RELEVANCE OF SURFACE SCIENCE TO CATALYSIS

Abstract It is to be regretted that only few catalysts have been studied from the point of view of “materials science”. Nevertheless, important information can be obtained on the function of catalysts when, for example, the surface composition of multicomponent catalysts is determined using surface science tools. Two examples of such investigations are discussed: PdAg alloys and NiCu alloys. The data on PdAg alloys show that the vibrational spectra of CO and possibly also the catalytic behaviour of the alloys can be explained by the dilution of palladium in silver, i.e. by essentially “geometrical” effects. The data on NiCu alloys show that the Fischer-Tropsch synthesis of hydrocarbons is a reaction that requires ensembles of several active atoms to occur.

Surface composition and catalysis by alloys: on the relevance of surface science to catalysis

It is to be regretted that only few catalysts have been studied from the point of view of “materials science”. Nevertheless, important information can be obtained on the function of catalysts when, for example, the surface composition of multicomponent catalysts is determined using surface science tools. Two examples of such investigations are discussed: PdAg alloys and NiCu alloys. The data on PdAg alloys show that the vibrational spectra of CO and possibly also the catalytic behaviour of the alloys can be explained by the dilution of palladium in silver, i.e. by essentially “geometrical” effects. The data on NiCu alloys show that the Fischer-Tropsch synthesis of hydrocarbons is a reaction that requires ensembles of several active atoms to occur.

Morphology and electronic structure of Si–SiO2 interfaces and Si surfaces

This paper will concern itself primarily with effects related to the Si–SiO2 interface for thermal oxides used as the gate dielectric in MOS structures. Studies of the morphology, chemistry, and electronic structure of the Si–SiO2 interface have been performed using two approaches. First, oxides are grown on Si substrates at aroung 1000 °C to thicknesses of around 1000 Å. Of interest here are oxidation kinetics, interface morphology and composition, interface electronic state density, and oxide impurity content. A microscopic understanding of these properties has been the goal of the second type of study performed, using the tools of surface science to investigate single-crystal surfaces. In this paper, we will review some of the important aspects of each of these two approaches. Finally, the relationship between them will be discussed and further studies to tie them together suggested.