Franz J. Himpsel

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The limits of pushing storage density to the atomic scale are explored with a memory that stores a bit by the presence or absence of one silicon atom. These atoms are positioned at lattice sites along self-assembled tracks with a pitch of five atom rows. The memory can be initialized and reformatted by controlled deposition of silicon. The writing process(More)
It has been a long-standing goal to create magnetism in a non-magnetic material by manipulating its structure at the nanoscale. Many structural defects have unpaired spins; an ordered arrangement of these can create a magnetically ordered state. In this article we predict theoretically that stepped silicon surfaces stabilized by adsorbed gold achieve this(More)
It has been proposed that the Si(557)-Au surface exhibits spin-charge separation in a one-dimensional electron liquid. Two narrowly spaced bands are found which exhibit a well-defined splitting at the Fermi level. That is incompatible with the assignment to a spinon-holon pair in a Luttinger liquid. Instead, we propose that the two bands are associated with(More)
DESCRIPTION. The Journal of Physics and Chemistry of Solids is a well established international medium for publication of research in condensed matter and materials science. Emphasis is placed on experimental and theoretical work which contributes to a basic understanding of and new insight into the properties and behavior of condensed matter. General areas(More)
Gold atom chains on vicinal Si(111) surfaces exhibit an unusual doublet of half-filled bands, whose origin has remained uncertain. The splitting is identified by angle-resolved photoemission as a spin splitting induced by the spin-orbit interaction (Rashba effect), in agreement with a theoretical prediction by Sánchez-Portal, Riikonen, and Martin. This(More)
A vicinal surface of silicon is found that exhibits an atomically accurate step pattern with a period of 5.73 nm, corresponding to 17 atomic rows per ͑111͒ terrace. It can be viewed as reconstructed Si͑557͒ surface, where a triple step is combined with a single Si͑111͒7ϫ7 unit. The driving forces for establishing regular step patterns are discussed.(More)
Highly regular arrays of steps are produced on vicinal Si͑111͒7ϫ7. The step edges are atomically straight for up to 2ϫ10 4 lattice sites. The terraces are single domain, which produces a minimum kink width of 2.3 nm ͑half a 7ϫ7 unit cell͒ and thus a high barrier for creating kinks. Criteria for obtaining optimum step arrays are established, such as the(More)
Polarization-dependent near edge X-ray absorption fine structure (NEXAFS) spectroscopy was used to determine the ordering of octadecyltrichlorosilane (OTS) molecules in self-assembled (SA) films on Si/SiOx. Coverages of adsorbed material for different SA films were determined by integration of the NEXAFS signal due entirely to the C 1s absorption. The(More)
Copper and zinc phthalocyanines and porphyrins are used in organic light emitting diodes and dye-sensitized solar cells. Using near edge x-ray absorption fine structure (NEXAFS) spectroscopy at the Cu 2p and Zn 2p edges, the unoccupied valence states at the Cu and Zn atoms are probed and decomposed into 3d and 4s contributions with the help of density(More)
The photodissociation of the amide bond by UV light and soft x-rays is investigated by x-ray absorption spectroscopy at the C, N, and O 1s edges. Irradiation leaves a clear and universal signature for a wide variety of amides, ranging from oligopeptides to large proteins and synthetic polyamides, such as nylon. As the π∗ peak of the amide bond shrinks, two(More)