In situ monitoring magnetism and resistance of nanophase platinum upon electrochemical oxidation

• Eva-Maria Steyskal,
• Stefan Topolovec,
• Stephan Landgraf,
• Heinz Krenn and
• Roland Würschum

Beilstein J. Nanotechnol. 2013, 4, 394–399, doi:10.3762/bjnano.4.46

• regime of electrooxidation. Fully reversible variations of the electrical resistance and the magnetic moment of 6% and 1% were observed upon the formation or dissolution of a subatomic chemisorbed oxygen surface layer, respectively. The increase of the resistance, which is directly correlated to the

Pure hydrogen low-temperature plasma exposure of HOPG and graphene: Graphane formation?

• Baran Eren,
• Dorothée Hug,
• Laurent Marot,
• Rémy Pawlak,
• Marcin Kisiel,
• Roland Steiner,
• Dominik M. Zumbühl and
• Ernst Meyer

Beilstein J. Nanotechnol. 2012, 3, 852–859, doi:10.3762/bjnano.3.96

• chemisorbed on the surface, and a small portion will be ionized (required energy Te: 13.6 eV). The atomic ion implantation may also hydrogenate the other side of the surface layer and even some other subsurface layers. The 3.5 eV plasma used in this work results in an ion impact energy (εi) of 12.6 eV on the

Imaging ultra thin layers with helium ion microscopy: Utilizing the channeling contrast mechanism

• Gregor Hlawacek,
• Vasilisa Veligura,
• Stefan Lorbek,
• Tijs F. Mocking,
• Antony George,
• Raoul van Gastel,
• Harold J. W. Zandvliet and
• Bene Poelsema

Beilstein J. Nanotechnol. 2012, 3, 507–512, doi:10.3762/bjnano.3.58

• surface layer of the relevant material (SiO2, PFS, or MS). As a consequence of the identical strip width for PFS and MS strips, we do not know a priori which stripe is which. However, we assign the bright structureless areas to the uncovered SiO2/Si substrate. It is understood that because of the

Functionalised zinc oxide nanowire gas sensors: Enhanced NO₂ gas sensor response by chemical modification of nanowire surfaces

• Eric R. Waclawik,
• Jin Chang,
• Andrea Ponzoni,
• Isabella Concina,
• Dario Zappa,
• Elisabetta Comini,
• Nunzio Motta,
• Guido Faglia and
• Giorgio Sberveglieri

Beilstein J. Nanotechnol. 2012, 3, 368–377, doi:10.3762/bjnano.3.43

• , which is comparable with the depth of the depletion region, the nanoparticles are likely to be fully depleted of electrons, different to the case of nanowires, which feature a depleted surface layer but also possess an unaltered “bulk” core due to their much larger diameter (about 50 nm, from Figure 1

Noncontact atomic force microscopy study of the spinel MgAl₂O₄(111) surface

• Morten K. Rasmussen,
• Kristoffer Meinander,
• Flemming Besenbacher and
• Jeppe V. Lauritsen

Beilstein J. Nanotechnol. 2012, 3, 192–197, doi:10.3762/bjnano.3.21

• triangular patches, the orientation and coverage of which are in agreement with the theoretical predictions for an oxygen-terminated surface with a certain percentage of the surface-layer atoms removed. Results and Discussion Figure 2a shows a large-scale NC-AFM image of the freshly prepared MgAl2O4(111

• in practice are considered as one single O surface layer [15]. As also indicated on the oxygen-terminated surface in Figure 1b, the primitive surface unit cell in the hexagonal representation, ahex, has a lattice constant of 5.72 Å. Considering that the crystal is prepared under an oxygen atmosphere

• parameter of 6√3·ahex = 5.9 nm, and the 30° orientation matches the experimentally observed structure. The amount of oxygen removed corresponds to 114 out of 432 per superstructure unit cell, leading to a total decrease in the initially O4 surface layer to O2.9, which is close to the theoretically predicted

Improvement of the oxidation stability of cobalt nanoparticles

• Celin Dobbrow and
• Annette M. Schmidt

Beilstein J. Nanotechnol. 2012, 3, 75–81, doi:10.3762/bjnano.3.9

• oxygen diffusion process across the oxidized surface layer [17]. From the initial susceptibility χini/χini,0 of the quasi-static magnetization curves we observe a similar trend as for Ms/Ms,0 (Figure 4), however, there is a significant deviation from the linear behavior for high magnetization-loss values

Size-dependent phase diagrams of metallic alloys: A Monte Carlo simulation study on order–disorder transitions in Pt–Rh nanoparticles

• Johan Pohl,
• Christian Stahl and
• Karsten Albe

Beilstein J. Nanotechnol. 2012, 3, 1–11, doi:10.3762/bjnano.3.1

• below 8 atom % at temperatures as low as 50 K, the excess platinum atoms do not dissolve inside the rhodium but they tend to stay at the surface and form a completely ordered surface layer (Figure 4, particles 1 and 2). This is a consequence of the preferred segregation of platinum atoms. The reason for

• interesting features for the two-phase equilibrium between the D022- and the pure rhodium phase in the particle. In Figure 4, for particle 3, we see that pyramid-shaped ordered D022-domains have formed below the (100) facets. The ordered surface layer of the (100) facet is compatible with D022-ordering. This

• concentration the surface platinum concentration increases again. At 60 atom % platinum concentration we find a completely 40-ordered particle with a surface layer of platinum (Figure 4, particle 9). The consequence of having the top layer entirely filled with platinum is that the 40-phase does not broaden its

Direct monitoring of opto-mechanical switching of self-assembled monolayer films containing the azobenzene group

• Einat Tirosh,
• Enrico Benassi,
• Silvio Pipolo,
• Marcel Mayor,
• Michal Valášek,
• Veronica Frydman,
• Stefano Corni and
• Sidney R. Cohen

Beilstein J. Nanotechnol. 2011, 2, 834–844, doi:10.3762/bjnano.2.93

• replicated to generate the starting conformation of the SAM is also shown as a black rectangle. It reproduces the periodicity of bright spots in the STM images of [3]. Only the Au atoms of the first surface layer are shown. (b) Snapshot from the MD simulation with the spherical probe (in green) upon the thio

The atomic force microscope as a mechano–electrochemical pen

• Christian Obermair,
• Andreas Wagner and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2011, 2, 659–664, doi:10.3762/bjnano.2.70

• chemical bonds mechanically [17][18]. As the experiments have been performed under environmental conditions, especially in the presence of oxygen, the formation of a surface layer on the gold substrate involving copper oxide/hydroxide and/or other compounds such as thiols is possible. The alternative

Nanoscaled alloy formation from self-assembled elemental Co nanoparticles on top of Pt films

• Luyang Han,
• Ulf Wiedwald,
• Johannes Biskupek,
• Kai Fauth,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2011, 2, 473–485, doi:10.3762/bjnano.2.51

• indicate a thin surface layer of Pt-rich CoxPt1−x alloy on top of the Pt (seen by the weaker absorption contrast). Note that this sample has not been covered by any protective layer. The left image shows the high angle annular dark-field (HAADF) image of the sample shown in Figure 8 using scanning TEM. EDX

Extended X-ray absorption fine structure of bimetallic nanoparticles

• Carolin Antoniak

Beilstein J. Nanotechnol. 2011, 2, 237–251, doi:10.3762/bjnano.2.28

• indicating that the volume diffusion is still inadequate in this method. For gas phase synthesised nanoparticles, a possible surface segregation of Pt has recently been discussed [82] as it is also known for thin FePt films [83]. In addition, an indication of a stronger lattice expansion towards the surface

• layer was found by analysis of transmission electron microscope (TEM) images [82]. However, since the particles were exposed to air before being transferred into the TEM, oxidation may also be responsible for the lattice expansion at the surface layers. In order to exclude the influences of oxidation

Preparation and characterization of supported magnetic nanoparticles prepared by reverse micelles

• Ulf Wiedwald,
• Luyang Han,
• Johannes Biskupek,
• Ute Kaiser and
• Paul Ziemann

Beilstein J. Nanotechnol. 2010, 1, 24–47, doi:10.3762/bjnano.1.5

• , the larger particles and the film gave similar results. These findings immediately suggest that in case of the film and the larger NPs, a Pt surface layer approximately one monolayer thick was formed which, in turn, strongly impedes further oxidation. For 4.9 nm FePt NPs (and smaller) this Pt surface

• layer is no longer complete and thereby loses its protecting effect. This latter behavior may have its origin in the strong compositional change within the interior of the particle induced by Pt segregation. As an example, for 4.9 nm NPs, a complete Pt shell with thickness of one monolayer segregated

Sensing surface PEGylation with microcantilevers

• Natalija Backmann,
• Natascha Kappeler,
• Thomas Braun,
• François Huber,
• Hans-Peter Lang,
• Christoph Gerber and
• Roderick Y. H. Lim

Beilstein J. Nanotechnol. 2010, 1, 3–13, doi:10.3762/bjnano.1.2

• reversible collapse when switching between good and poor solvent conditions, respectively. Keywords: AFM; cantilever sensor; polyethylene glycol; polymer brush; reversible collapse; static mode; Introduction Polyethylene glycol (PEG) is often used as a protein-resistant surface layer in biomedicine and