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See detailComputer Simulations of the Sputtering of Metallic, Organic, and Metal−Organic Surfaces with Bin and C60 Projectiles
Delcorte, Arnaud; Leblanc, Christophe ULg; Poleunis, Claude et al

in Journal of Physical Chemistry C: Nanomaterials, Interfaces, and Hard Matter (2013), 117

This study focuses on the microscopic modeling of 0–25 keV Bi1–3–5 and C60 cluster impacts on three different targets (Au crystal, adsorbed Au nanoparticle, and organic solid), using molecular dynamics ... [more ▼]

This study focuses on the microscopic modeling of 0–25 keV Bi1–3–5 and C60 cluster impacts on three different targets (Au crystal, adsorbed Au nanoparticle, and organic solid), using molecular dynamics simulations, and on the comparison of the calculated quantities with recent experimental results, reported in the literature or obtained in our laboratory. The sputtering statistics are reported, showing nonlinearity of the sputtering yields with the number of cluster atoms at the same incident velocity for Bi1–5 bombardment. They are compared to experiments (especially for the organic target), and the microscopic explanation of the observations is analyzed. The results show that the respective behaviors and performances of the different projectiles are strongly dependent on the target, with clusters of heavy Bi atoms being more efficient at sputtering gold and, conversely, fullerene clusters inducing the largest sputtering yields of the organic material (mass matching). For organic targets, some important and novel conclusions of this work are the following: (i) The increase of the sputtering yield when going from Bi atoms to Bi clusters is insufficient to explain the much larger increase of characteristic ion yields, suggesting a projectile-dependent ionization probability. (ii) The extent of molecular fragmentation follows the order of Bi > Bi3 > Bi5 > C60, that is, softer emission with larger clusters. (iii) Even 5–10 keV Bi atoms create collective molecular motions and craters in the polymeric solid, though the collision cascades are rather dilute. Finally, a second series of simulations performed at low energies predict that 0.1–1 keV Bin clusters should not provide better results for sputtering and depth profiling than isoenergetic single atoms. [less ▲]

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See detailComparison of functionalized carbon nanofibers and multi-walled carbon nanotubes as supports for Fe-Co nanoparticles
Vidick, Deborah; Herlitschke, Marcus; Poleunis, Claude et al

in Journal of Materials Chemistry A (2013), 1(6), 2050-2063

Multi-walled carbon nanotubes (MWCNT) and nanofibers (CNF) have been functionalized at their surfaces with chelating phosphine (PPh2) and ammonium (NMe3+) groups, as anchoring sites for metal complexes ... [more ▼]

Multi-walled carbon nanotubes (MWCNT) and nanofibers (CNF) have been functionalized at their surfaces with chelating phosphine (PPh2) and ammonium (NMe3+) groups, as anchoring sites for metal complexes. The surface functionalization has been monitored by XPS, elemental analyses, N-2 physisorption and/or SEM surface morphology analysis at each step. Bimetallic Fe-Co nanoparticles from two different starting cluster complexes, [HFeCo3(CO)(12)] (1) and (NEt4)[FeCo3(CO)(12)] (2), have been deposited onto the surfaces of the functionalized MWCNT and CNF as well as their pristine forms for comparison. The samples have been fully characterized before and after thermal treatment. The obtained nanoparticles were shown by TEM to be better dispersed and of smaller size on functionalized than on pristine supports. Magnetic characterization revealed blocked superparamagnetic Fe-Co nanoparticles together with paramagnetic ions on CNF as well as MWCNT. [less ▲]

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See detailElectrodeposition of mixed adherent thin films of poly(ethyl acrylate) and polyacrylonitrile onto nickel
Baute, Noëlle; Geskin, Victor M; Lazzaroni, Roberto et al

in e-Polymers (2004), (63), 1-20

Adherent thin polymer films have been prepared by sequential electrodeposition of ethyl acrylate (EA) and acrylonitrile (AN) onto nickel. Their composition has been studied by IR spectroscopy and time of ... [more ▼]

Adherent thin polymer films have been prepared by sequential electrodeposition of ethyl acrylate (EA) and acrylonitrile (AN) onto nickel. Their composition has been studied by IR spectroscopy and time of flight-secondary ion mass spectrometry. Morphology and thickness have been analyzed by atomic force microscopy and ellipsometry, respectively, and compared to single component films of PEA and PAN. No microphase separation was detected in the mixed PEA/PAN films. These show a granular morphology comparable to that of PAN films. The grains contain the two constitutive polymers, as confirmed by the selective thermal degradation of PEA. [less ▲]

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See detailChemical Recognition of Antioxidants and UV-light Stabilizers on the Surface of Polypropylene : Atomic Force Microscopy with Chemically Modified Tips
Duwez, Anne-Sophie ULg; Poleunis, Claude; Bertrand, Patrick et al

in Langmuir (2001), 17

We show in this paper that it is possible to locally detect additives on the surface of polypropylene with chemically modified atomic force microscopy (AFM) tips. Gold-coated AFM tips modified with methyl ... [more ▼]

We show in this paper that it is possible to locally detect additives on the surface of polypropylene with chemically modified atomic force microscopy (AFM) tips. Gold-coated AFM tips modified with methyl and hydroxyl terminated self-assembled alkanethiol monolayers were used to measure adhesion forces on a process-stabilizing agent (Irgafos 168), an antioxidant (Irganox 1010), and UV-light stabilizers (Tinuvin 770, Dastib 845, Chimassorb 944, and Hostavin N30). Pull-off force measurements carried out on these pure additive films have shown that it is possible to discriminate between antioxidants and UV-light stabilizers. We have evidenced a characteristic fingerprint for each additive, according to the functionality of the tip used and themediumwherein the force measurements are realized (water or nitrogen atmosphere). Similarly we have measured pull-off forces on a melt-pressed polypropylene sample stabilized with Irgafos 168, Irganox 1010, and Tinuvin 770. These adhesion force measurements show that the extreme surface of the polymer is mainly made of a layer of Tinuvin 770. These results have been compared to those obtained from time-of-flight secondary ion mass spectrometry measurements [less ▲]

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