Вероятность ионизации атомов, распыленных при бомбардировке поверхности металлов одно- и многозарядными ионами

The processes of ionization of atoms sputtered under bombardment of clean metal surface by singly and multiply charged ions with kinetic energy of several keV were studied. Within the framework of simple phenomenological model of ion formation, the relaxation of local electron excitation in metal was taking into account. Analytical expressions for estimation of ionization probability of sputtered atoms was obtain. It was shown, that in comparison with singly charged ions, bombardment of metals with multiply charged ions results to significant increase of ionization probability of sputtered atoms due to more efficient excitation of electrons and increase of relaxation time of this excitation.

The adsorption of silicon on an iridium surface ruling out silicene growth

We followed the adsorption of Si on the Ir(111) surface via high resolution core level photoelectron spectroscopy, starting from the clean metal surface up to a coverage exceeding one monolayer.

STUDIES OF CLEAN METAL SURFACE RELAXATION EXPERIMENT–THEORY DISCREPANCIES

A series of Low-Energy Electron Diffraction Intensity vs. Voltage (LEED I–V) measurements for Rh(001), W(110) and Ti(0001) have been undertaken in order to help resolve discrepancies between experiment and theory for the surface relaxations of certain transition metals. LEED measurements and analysis indicate the following results for the change of first (d12) and second (d23) interlayer spacings, relative to the bulk interlayer spacing d0: for Rh(001), Δ d12/d0=-1.4± 1.4% and Δ d23/d0=-0.6± 1.4%; for W(110), Δ d12/d0=-3.0± 1.3% and Δ d23/d0=+0.2± 1.3%; and for Ti(0001), Δ d12/d0=-4.9± 1.0% and Δ d23/d0=+1.4± 1.0%. In each case, the new measurements help to resolve the experiment–theory surface relaxation discrepancies. In addition, two of these surfaces [W(110) and Ti(0001)] show substantial contractions in the first interlayer spacing, d12. Large relaxations for close-packed surfaces lend support to the promotion–hybridization picture of surface relaxation put forth recently by P. J. Feibelman [P. J. Feibelman, Phys. Rev.B53, 13740 (1996).] In addition to making new experimental determinations of surface relaxations, a secondary goal of this work is to characterize sources of error associated with LEED I–V methodology that have traditionally not been fully appreciated.

Surface Absorption of Monolayers

When the first paper describing the formation of self-assembled monolayers (SAMs) of octadecyltrichlorosilane [CH3(CH2)17SCl3, or OTS] by adsorption on SiO2 was published, it could not have been predicted that this area of research would become so important in only one decade. Although Zisman was the first to discover that monolayers can be prepared by adsorption of a surfactant onto a clean metal surface, the real revolution in the field occurred when Nuzzo and Allara showed that SAMs of alkanethiolates on gold can be prepared by adsorption of di-n-alkyl disulfides from dilute solutions. A decrease in the use of moisture-sensitive alkyl trichlorosilanes and the increased use of crystalline gold surfaces were two important reasons for the success of these SAMs. Indeed, monolayers of alkanethiolates on gold are the most studied SAMs to date and thus deserve the most detailed discussion.SAMs have been intensively studied in the past few years because of their relevance to science and technology. Due to their dense and stable structure, SAMs have potential applications in corrosion prevention, wear protection, and biosensing, for example. The ability to tailor both head and tail groups of the constituent molecules makes them ideal for gaining a more fundamental understanding of phenomena affected by competing intermolecular, molecular-substrate, and molecule-solvent interactions like ordering and growth, wetting adhesion, lubrication, and corrosion.