Metal nano clusters are of great importance in physical and chemical science. One simple method for obtaining metal clusters consists in the deposition of a metal film on an inert substrate followed ...by annealing at high temperature. After this procedure, the metal film reduces in small clusters, whose morphology depends on the annealing temperature and annealing time. In this work we present a grazing incidence small angle X-ray scattering (GISAXS) study carried out in situ to understand the nucleation and formation of Ni metal clusters. For this purpose uniform Ni metal films, of different thicknesses, were deposited onto an oxidized Si(0
0
1) substrate, and annealed at different temperatures in the range 400–800
K. Before annealing the samples were characterized by X-ray reflectivity measurements to exactly determine the values of the thickness and of the starting roughness. The GISAXS patterns show a surface roughness increase starting at about 600
K. By increasing the temperature the diffused intensity breaks in two lines around the reflectivity plane, indication of a characteristic length correlation of the roughness. This correlation length is maintained during the metal clusters formation.
In this work small angle coherent scattering data are presented for some biological tissues. The effect of low angle diffusion on the micro-beams dose distributions are assessed by means of a ...dedicated version of the EGS4 code. The atomic form factor tabulations were upgraded in EGS4 to include experimental values of compounds instead of obtaining the linear differential scattering coefficient from a simple weighted sum of the elemental components. In this manner, one includes the effects induced by both the large-scale arrangement of the sample structure and the molecular interference. It is shown that the inclusion of the measured form factors and cross-sections in the photon transport calculations induce not negligible effects in the dose deposited around the microbeams. The fact of not taking into account small angle scattering cross-sections may lead to underestimating the number of scattered photons reaching zones not directly illuminated. At the center of a microbeam planar array the effect can be as much as 100% for X-ray photons of 50
keV.
•Structural evolution of Co thin films upon intercalation under Graphene.•Identification of different contribution to the Co-Ir interface interaction.•Model of the Graphene effect on the Co film ...during the intercalation process.
Thin Co films intercalated between a Graphene capping layer and the Ir(111) surface are of interest for spintronics applications due to their peculiar magnetic properties and to their chemical stability. The structure, and then the magnetic properties, of the Co films depend on the intercalation process which is strongly influenced by the temperature, total amount of Cobalt and quality of the capping Graphene layer. In order to identify and disentangle the effects of these contributions, we report on the structural characterisation of four Co films as a function of thickness, annealing temperature, and Graphene capping. From the structural point of view, the deposition of Co on a hot Ir substrate mimics quite well the intercalation process proving the validity of the colander model describing the Graphene role during the process.
In this article, we present the current capabilities of the ID03 surface diffraction beamline for the characterisation of catalytic surfaces under reaction. The weak interaction of X-rays with matter ...makes it possible to design reactor set-ups which can sustain high temperatures and atmospheric pressures while probing the sample reactivity, structure and morphology with surface sensitive X-ray techniques. A few examples are presented as an illustration of the current capabilities.
The neutron optics package (NOP) is a collection of codes for the computation of reactor spectra, neutron reflectivity of crystals, mirrors and multilayers and other quantities as cross-sections, ...attenuation in materials and refractive index. These calculations rely on the use of a database of materials cross-sections and crystal structures. NOP is freely distributed as an extension of the X-ray package XOP (Sánchez del Rı́o, Dejus, SPIE Proceedings 3448 (1998) 340), from which it inherits the user interface and code structure. The NOP package can be used for estimating the reflectivity of optical elements as crystals and multilayers. The NOP output can also be used as an input for neutron instrument ray-tracing modules.
The attainment of ultrathin films of well ordered II–VI and III–V compound semiconductors is an active research area of the electrochemistry group at the University of Florence. The method employed ...is the electrochemical atomic layer epitaxy (ECALE) which is based on self limiting reactions such as underpotential deposition (UPD). Recently, the possibility of combining the electrodeposition at nanometer scale and the self assembly phenomena has been investigated. In particular, the ECALE method was used to deposit CdS on Ag(1
1
1) covered by a patterned hexadecanthiol (HDT) self assembled monolayer (SAM). In fact, the deposition of CdS only takes place on the uncovered silver substrate, whereas it is not possible on the thiols monolayers. The deposits have been characterized by electrochemical techniques and AFM measurements.
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