Conventional and manipulated growth of Cu-Cu(111)

Molecular beam epitaxy of Cu on Cu(111) was studied using thermal energy He scattering, in the temperature range between 100 and 450 K. Three-dimensional growth was observed in the whole temperature range. To determine the onset of various diffusion processes, submonolayer films formed by deposition at low temperature were annealed. Annealing proceeds in two steps. The first step is interpreted as a change in island shape, the second as Ostwald-ripening. A comparison with homoepitaxy on Pt(111) and Ag(111) is made. Growth manipulation was carried out by artificially increasing the island number density via intervention in the nucleation stage of each layer. The procedures applied were temperature reduction during nucleation as well as pulsed ion bombardment. These techniques enabled the convenient growth of good quality films consisting of a large number of monolayers. Finally, the use of oxygen as a surfactant modifying the growth mode was investigated. Under some growth conditions, pre-exposure of the surface to oxygen was found to induce weak He-intensity oscillations during deposition. The quality of the films grown in this way was, however, low

Manipulation of growth modes in heteroepitaxy: Ni-Cu(111)

Growth manipulation methods, which have been successfully used to improve the growth of homoepitaxialfilms, are applied to molecular beam epitaxy of the heteroepitaxial system Ni/Cu(111). The procedures applied are temperature reduction during nucleation and pulsed ion bombardment during deposition. While the first does not lead to smoother films, the ion beam assisted growth is successful in reducing the film roughness

Mixomicets quionofils

Presentem la descripció i caractéristiques diferencials de tres espècies de mixomicets quionòfils: Comatricba suksdorfii, Lamproderma sauteri i Diderma trevelyanii var. nivale, recol.lectades prop de la neu en fusió i en diferents localitats dels Pirineus catalans. Totes tres espècies són noves citacions per al catàleg micològic dels Països Catalans

Spontaneous formation of an ordered c(4x2)/(2x1) domain pattern on Ge(001)

Scanning-tunneling-microscopy measurements of Ge(001) reveal the presence of an ordered domain pattern consisting of c(4×2) and (2×1) domains arranged in stripes with a width of several dimer row spacings, oriented along the dimer rows. We suggest that the existence of a soft domain wall between the domains combined with a difference in the stress component along the dimer bond for the (2×1) and c(4×2) domains, respectively, can conspire to produce such an ordered domain phase. A simple model based on strain relaxation explains the observed size of the domain pattern