Antonella Rossi - Academia.edu (original) (raw)

Uploads

Papers by Antonella Rossi

Surface and Interface Analysis, 2001

The surface chemical state and composition of natural and synthetic enargite samples were charact... more The surface chemical state and composition of natural and synthetic enargite samples were characterized with X‐ray photoelectron spectroscopy (XPS). Freshly cleaved, powdered and ‘as received’ samples were analysed at liquid nitrogen temperature. For the natural ‘as received’ samples as well as for the natural and synthetic powdered samples the binding energies of Cu 2p3/2, As 3d5/2 and S 2p are consistently found at 932.5 ± 0.2, 43.9 ± 0.2 and 162.2 ± 0.2 eV, respectively. A second component of S 2p at 163.9 ± 0.2 eV is present and may be assigned to elemental sulphur. Freshly cleaved enargite samples showed binding energies of 43.2 and 161.3 eV, respectively, for As 3d5/2 and S 2p3/2. At the surface of crystals ‘as received’, an additional signal at ∽169 eV, referable to sulphate sulphur, is also present, as well as additional signals for Cu 2p3/2 (∽934 eV), and As 3d5/2 (∽45.5 eV). The thickness and the composition of this outer oxidized layer together with the composition of the interface beneath the film are calculated on the basis of a model developed for this purpose, taking into account the attenuation of the photoelectrons due to the contamination and the oxidized layer. An oxidized film of ∽0.5 nm is present at the surface of the ‘as received’ crystals whose composition was found to be ∽45% copper, 24% arsenic and 31% sulphur; hence, the oxidized layer appears to be enriched in arsenic compared with the bulk composition. The composition of the material beneath the oxidized layer was found to be enriched in copper and depleted in sulphur with respect to the bulk analysis. Any further study of the interaction of natural enargite samples with the environment has to take into account the existence of this thin outer layer. Copyright © 2001 John Wiley & Sons, Ltd.

Tribology Letters, Sep 15, 2007

Combinatorial testing has been performed on zinc dialkyldithiophosphate (ZnDTP)-containing lubric... more Combinatorial testing has been performed on zinc dialkyldithiophosphate (ZnDTP)-containing lubricants, to investigate the effects of contact pressure on the formation of tribochemical films. Contact pressures ranging from 25 to 500 MPa were applied in ball-on-disc tribotests with oscillating load. Both the ball and the disc were investigated by means of small-area and imaging X-ray photoelectron spectroscopy (XPS). The thickness and the composition of the reaction layer were estimated from the XPS data. The thickness of the reaction layer in the tribologically stressed areas of the ball and of the disc increased with both temperature and contact pressure. The reaction layer mainly consisted of short-chain poly(thio)phosphates, shorter chains being observed at higher contact pressures. At high pressures, the presence of a thick, high-toughness short-chain poly(thio)phosphate layer can explain the lower friction and dimensional wear coefficients observed. On the ball, similar anti-wear film formation mechanisms were observed as on the disc, zinc sulphide being deposited in the post-contact region.

Tribology Letters, Oct 11, 2011

To investigate the chemical changes occurring at metal/lubricant interfaces under tribological co... more To investigate the chemical changes occurring at metal/lubricant interfaces under tribological conditions in the boundary-lubrication regime, an in situ system for conducting quantitative tribological measurements has been constructed by combining an attenuated total reflection Fourier-transform infrared (ATR/FT-IR) spectrometer with a reciprocating tribometer. By periodically acquiring ATR/FT-IR spectra during sliding, spectroscopic changes due to thermal and/or tribochemical reactions occurring at the metal/oil interface can be monitored and correlated with friction measurements. The usefulness of this tribological test system has been demonstrated by performing ATR tribological experiments in the presence of a poly-aolefin base oil at high temperature (423 K) on iron-coated germanium ATR crystals.

Fresenius Journal of Analytical Chemistry, Jul 3, 2000

A quantitative method based on FTIR has been developed to determine carbonate in synthetic apatit... more A quantitative method based on FTIR has been developed to determine carbonate in synthetic apatites. The method measures the evolved CO 2 after reaction of 50 mg apatite with 2 mL of hydrochloric acid (0.5 M) in a reaction vessel, heated to 40°C. The CO 2 evolved was swept by a carrier of nitrogen to a laboratory-made infrared gas cell of 39 mm pathlength and 490 µL volume. The signals were recorded as a function of time and the areas of the chemigram peaks obtained from the measurements in the wavenumber range of 2500-2150 cm-1 , were interpolated using a calibration curve. The method can be used to study apatites with carbonate contents below 0.2% with a sampling frequency of 8 h-1 .

Chemosphere, Jun 1, 2022

Low-cost and largely available industrial by-products such as calcite (CaCO3) have been considere... more Low-cost and largely available industrial by-products such as calcite (CaCO3) have been considered as sorbents to remediate wastewaters from toxic elements, such as lead, in compliance with the European circular economy strategy. To date few articles are reporting results on lead sorption at the calcite-water solution interface by X-ray photoelectron spectroscopy (XPS) and this investigation aims to clarifying the mechanism of the interaction of Pb2+ model solutions over a wide concentration range, from 0.1 μM to 80 mM, with commercial calcite. X-ray powder diffraction (XRPD), scanning electron microscopy (SEM, EDX) and XPS analysis indicate that when CaCO3 particles are soaked in Pb2+ 0.1 mM and 1 mM solutions, hexagonal platelets of hydrocerussite [(PbCO3)2 Pb(OH)2] precipitate on its surface. When the concentration of Pb2+ is equal or higher than 40 mM, prismatic acicula of cerussite [PbCO3] precipitate. Solution analysis by atomic emission spectroscopy (ICP-AES) and ICP-mass spectrometry (ICP-MS) indicate that Pb2+ removal efficiency is nearly 100%; when the initial Pb2+ concentration was equal to 0.1 μM it was below the limit of detection (LOD) and the efficiency could not be determined. The sorption capacity (qe) increases linearly with increasing initial Pb2+ concentration up to a value of 1680 (20) mg/g when the initial Pb2+concentration is 80 mM. These findings suggest that heterogeneous nucleation and surface co-precipitation occur and calcite can be well considered a very promising sorbent for Pb2+ removal from wastewaters within a wide initial concentration range.

Tribology Letters, Sep 30, 2006

The surface reactivity of tributyl thiophosphate on iron surfaces has been studied in situ by att... more The surface reactivity of tributyl thiophosphate on iron surfaces has been studied in situ by attenuated total reflection Fouriertransform infrared spectroscopy, X-ray photoelectron spectroscopy and temperature-programmed reaction and desorption spectroscopies. The results show that at temperatures lower than 373 K the molecule forms a physisorbed layer on the iron substrate. At 373 K a reaction takes place with the formation of an organic layer, together with iron polyphosphate and sulfate. At higher temperatures temperature-programmed desorption results suggest that the mechanism involves P-O bond scission to yield butoxy groups. This could be preceded by P=S bond scission to give tributyl phosphite, which then, in turn, undergoes P-O bond scission to produce butoxy groups. The results obtained following tribological testing are in agreement with those of thermal tests: evidence of polyphosphate and sulfate formation is found.

ACS Nano, Nov 24, 2021

A tripod molecule incorporating a C60 photocatalyst into a rigid scaffold with disulfide legs was... more A tripod molecule incorporating a C60 photocatalyst into a rigid scaffold with disulfide legs was designed and synthesized for the stable and robust attachment of C60 onto an Au-coated atomic force microscope (AFM) tip. The "tripod-C60" was immobilized onto the tip by forming S-Au bonds in the desired orientation and a dispersed manner, rendering it suitable for the oxidation and scission of single molecules on a countersurface, thereby functioning as "molecular shears". A DNA origami with a well-defined structure was chosen as the substrate for the tip-induced oxidation. The gold-coated, C60-functionalized AFM tip was used for both AFM imaging and oxidation of DNA origami upon visible-light irradiation. The localized and temporally controlled oxidative damage of DNA origami was successfully performed at the single-molecule level via singlet-oxygen (1O2) generation from the immobilized C60 on the AFM tip. This oxidative damage to DNA origami can be carried out under ambient conditions in a fluid cell at room temperature, rendering it well-suited for the manipulation of a variety of species on surfaces via a spatially and temporally controlled oxidation reaction triggered by 1O2 locally generated from the immobilized C60 on the AFM tip.

Materials and Corrosion-werkstoffe Und Korrosion, May 8, 2016

An electrochemical sensor has been tested on brass reference samples and applied on a mouthpiece ... more An electrochemical sensor has been tested on brass reference samples and applied on a mouthpiece of a historical brass instrument. Using a phosphate buffer solution pH 7 with 10−2, 10−3 and 10−4 M NaCl, the electrochemical response (open circuit potential, polarisation resistance) of the sensor corresponds to the results obtained in a traditional electrochemical cell. XPS surface analysis has shown that the brass surface composition after 7 min contact with the sensor is not altered when using 10−3 or 10−4 M NaCl. The sensor is fit for purpose and has already been applied in brass wind instruments.

Langmuir, Feb 17, 2000

Octadecylphosphoric acid ester is shown to self-assemble on amorphous/nanocrystalline tantalum ox... more Octadecylphosphoric acid ester is shown to self-assemble on amorphous/nanocrystalline tantalum oxide (Ta2O5) layers deposited by physical vapor deposition onto glass substrates. Three complementary surfaceanalytical techniques (angle-dependent X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, and atomic force microscopy in lateral force mode), showed that a 2.2 nm thick, "tailsup"-oriented adlayer is formed, which displays local near-hexagonal order, strong P-O-Ta bonding, and the presence of (-P-O-)2Ta species. A model for the binding and the structural organization of the octadecyl phosphate molecules on the tantalum oxide surface is proposed involving direct coordination of the terminal phosphate headgroup to Ta(V) cations forming a strong complexation bond, two types of bonding of the octadecyl phosphate with both monodentate and bidentate phosphate-Ta(V) coordinative interactions, and, locally, the formation of a coincidence lattice of approximately hexagonal structure defined by both the location of Ta(V) cation sites and an intermolecular spacing between the octadecyl phosphate ligands of approximately 0.5 nm. This is very similar to the self-assembled monolayer structure of long-chain alkanethiols on gold. The use of phosphoric acid ester derivatives is believed to have potential for designing specific interface architectures in sensor technology, in surface modification of oxide-passivated metallic biomaterials, and in composite metal (oxide)-polymer interfaces.

CRC Press eBooks, May 31, 2023

Surface and Interface Analysis, Jun 26, 2020