Showing papers by "Harald Brune published in 1994"
TL;DR: In this article, a crossover from fractal to dendritic growth in two dimensions on the microscopic scale was observed in a Pt(lll) surface, and the authors suggest that the increasing importance of anisotropy of edge diffusion at higher flux is responsible for this crossover.
Abstract: THE similarity of many patterns formed in non-equilibrium growth processes in physics, chemistry and biology is conspicuous, and many attempts have been made to discover common mechanisms underlying their formation1. A central question is what causes some patterns to be dendritic (symmetrically branched, like snowflakes) and others fractal (randomly ramified). In general, the transition from fractal to dendritic growth is regarded as a manifestation of the predominance of anisotropy over random noise in the growth process. In electrochemical deposition, this transition is observed as the growth speed is varied2,3. Here we report a crossover from fractal to dendritic growth in two dimensions on the microscopic scale. We use the scanning tunnelling microscope to study diffusion-limited aggregation of silver atoms on a Pt(lll) surface. The transition occurs as the deposition flux is increased, and our observations suggest that the increasing importance of anisotropy of edge diffusion at higher flux is responsible for this crossover. We anticipate that a similar phenomenon may operate in three-dimensional crystal growth.
211 citations
TL;DR: The mechanism of strain relief for compressively stressed Ag layers epitaxially grown on Pt(111) is studied by scanning tunneling microscopy and the introduction of a phase shift of one set of domain walls allows the system to account for the energy difference of fee and hcp stacking.
Abstract: The mechanism of strain relief for compressively stressed Ag layers epitaxially grown on Pt(111) is studied by scanning tunneling microscopy. The strain in the compressed commensurate (1X1) Ag monolayer on Pt(111) is relieved in the bilayer by the formation of two weakly incommensurate structures: the metastable striped incommensurate phase, which converts into a trigonal network of domain walls upon annealing. This network is a general case for isotropic strain relief realized by the crossing of domain walls. The introduction of a phase shift of one set of domain walls allows the system to account for the energy difference of fee and hcp stacking. The stability of unidirectional via isotropic strain relief and the respective structures of domain walls is generally discussed for surface reconstructions and metal epitaxy of hexagonal-close-packed surfaces.
151 citations
TL;DR: The data show that dimers are stable nuclei for T less-than-or-equal-to 110 K, which facilitates quantitative comparison with rate equations from nucleation theory, and the migration barrier E(m) = 157 +/- 10 meV is determined for Ag adatoms on Pt(111) and compared with theoretical values.
Abstract: Nucleation has been studied on atomic scale for Ag deposition on a Pt(111) surface at low temperature (50-120 K) by means of variable-temperature scanning tunneling microscopy. From island density versus coverage data, the transition from the initial steps of nucleation to growth and coalescence has been studied as a function of temperature. The data show that dimers are stable nuclei for T less-than-or-equal-to 110 K, which facilitates quantitative comparison with rate equations from nucleation theory. The migration barrier E(m) = 157 +/- 10 meV is determined for Ag adatoms on Pt(111) and compared with theoretical values.
144 citations
TL;DR: The chiral stationary phase for Epitaxial Growth Reference LNS-ARTICLE-1994-001 shows good chiral recognition ability and the ability to reprogram the chiral assembly process for self-Assembly.
Abstract: Keywords: Nucleation ; Aggregation ; Self-Assembly ; Epitaxial Growth Reference LNS-ARTICLE-1994-001doi:10.1103/PhysRevLett.73.2143View record in Web of Science Record created on 2009-04-14, modified on 2017-05-12
13 citations