Dissociation of CH Species on Ni(111):A HREELS Study

The isothermal dissociation rate of CCH and CH on Ni(111) was measured by following, with HREEL spectroscopy, the intensity of the CH stretching peak as a function of time. By repeating the experiment at several different temperatures we obtained an activation energy of 8±3 kcal/mol for the CCH dissociation reaction and of 12±3 kcal/mol for the CH dissociation reaction. Pre-exponential factors were found to be 10^3±1 s-1 in both cases. Independent thermal desorption spectra show a feature at 470 K and a tail extending up to 600 K which can be assigned to the CCH dissociation and the CH dissociation respectively. The two experiments are quantitatively consistent

Surface structure of Pd(111) with less than half a monolayer of Zn

We have characterized the structural properties of submonolayer amounts of Zn on Pd(111) using scanning tunneling microscopy (STM) and spot-profile analysis low energy electron diffraction (SPA-LEED). Following room temperature deposition of E0.06 monolayers (ML) Zn onto Pd(111), we observe the substitution of Zn for Pd in the surface layer. At E0.20 ML of deposited Zn, STM reveals a locally ordered phase with a 2/sqrt3x2/sqrt3R30deg unit cell located near Zn substitutions; SPA-LEED patterns reveal the same periodicity. We attribute this phase to the metastable bonding of atoms or clusters predominantly in hollow sites surrounding Zn substitutions in the surface layer. At Therta=0.4 ML, STM images reveal local 2/sqrt3x2/sqrt3R30deg and (2x1) ordering on surfaces annealed to 350 K. At coverages near 0.5 ML, both STM and SPA-LEED show the onset of the formation of the (2x1) ordering associated with the Zn: Pd 1 : 1 alloy phase. At all coverages, the surface is dominated by island growth; the islands\u2019 size and density is shown to depend critically on annealing at temperatures as low as 350 K. These results provide insight into the structural features of a Zn/Pd(111) coverage regime that has been much debated in recent years

Kinetics of the C2H2 Dissociation on Ni(111): A HREELS Study

The C2H2 isothermal dissociation rate on Ni(111) was measured by following, with HREEL spectroscopy, the intensity of the CH stretching peak as a function of time. By repeating the experiment at several different temperatures we have obtained an activation energy of 1.2±0.1 eV/molecule and a pre-exponential factor of 10^14±1 s-1 for the first step of the C2H2 dissociation reaction.

CO dissociation on Ni(100) studied by Auger electron spectroscopy

Auger Electron Spectroscopy (AES) has been used to investigate the kinetics of CO dissociation on a Ni(100) single crystal surface. The coverages of carbidic carbon and oxygen on the surface have been monitored as a function of time for different sample temperatures (453 K ≤ T ≤ 573 K) and CO pressures (3 × 10−7 mbar ≤ PCO ≤ 3 × 10−6 mbar). The experimental data have been compared to the results of rate equations relative to different dissociation models. This procedure led to the identification of the probable reaction mechanism, whose most relevant step in this pressure range resulted to be the rupture of the CO bond. The activation energy of the process has been evaluated

Ferromagnetic Stoner excitations detected by electron-energy-loss spectroscopy

Spin-flip Stoner excitations have been detected in Fe80B15Si5 using simple electron-energy-loss spectroscopy via the strong energy dependence of the exchange process involved. The Stoner-excitation contribution, obtained as the difference between energy-loss spectra taken with low-energy and high-energy primary electrons, is in good agreement with the results of spin-polarized electron-energy-loss spectroscopy and with theoretical predictions

Patent number WO2015124595: Method for the catalyzed reduction of halogen oxyanions in aqueous solutions

Titolo brevetto italiano: metodo per la riduzione catalizzata di ossoanioni di alogeni in soluzioni acquose.; Domanda di brevetto in Italia n. 102014902234549 del 18/02/2014, pubblicata in data 19/08/201

Method for the catalyzed reduction of halogen oxyanions in aqueous solutions

A method for removing halogen oxyanions, in particular chlorine and bromine, by hydrogenation reduction catalysed with supported catalysts based on rhenium and noble metals of subgroup VIII of the Periodic Table of the Elements is herein disclosed. The combination of the noble metals with rhenium has proved to considerably increase the catalytic efficiency of such metals