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Beilstein Journal of Nanotechnology

Azar Aliabadi, Bernd Büchner, Vladislav Kataev, Tobias Rüffer
For future molecular spintronic applications the possibility to modify and tailor the magnetic properties of transition-metal complexes is very promising. One of such possibilities is given by the countless derivatization offered by carbon chemistry. They allow for altering chemical structures and, in doing so, to tune magnetic properties of molecular spin-carrying compounds. With emphasis on the interplay of the spin density distribution of mononuclear and magnetic superexchange couplings of trinuclear bis(oxamato)-type complexes we review on efforts on such magneto-structural correlations...
2017: Beilstein Journal of Nanotechnology
Enrique A López-Guerra, Santiago D Solares
We explore the contact problem of a flat-end indenter penetrating intermittently a generalized viscoelastic surface, containing multiple characteristic times. This problem is especially relevant for nanoprobing of viscoelastic surfaces with the highly popular tapping-mode AFM imaging technique. By focusing on the material perspective and employing a rigorous rheological approach, we deliver analytical closed-form solutions that provide physical insight into the viscoelastic sources of repulsive forces, tip-sample dissipation and virial of the interaction...
2017: Beilstein Journal of Nanotechnology
Dieter Vollath, David Holec, Franz Dieter Fischer
Structure and properties of small nanoparticles are still under discussion. Moreover, some thermodynamic properties and the structural behavior still remain partially unknown. One of the best investigated nanoparticles is the Au55 cluster, which has been analyzed experimentally and theoretically. However, up to now, the results of these studies are still inconsistent. Consequently, we have carried out the present ab initio study of the Au55 cluster, using up-to-date computational concepts, in order to clarify these issues...
2017: Beilstein Journal of Nanotechnology
Meike Koenig, Joerg Lahann
No abstract text is available yet for this article.
2017: Beilstein Journal of Nanotechnology
Mónica Mendes, Khrystyna Regeta, Filipe Ferreira da Silva, Nykola C Jones, Søren Vrønning Hoffmann, Gustavo García, Chantal Daniel, Paulo Limão-Vieira
High-resolution vacuum ultraviolet photoabsorption measurements in the wavelength range of 115-320 nm (10.8-3.9 eV) have been performed together with comprehensive relativistic time-dependent density functional calculations (TDDFT) on the low-lying excited sates of tungsten hexacarbonyl, W(CO)6. The higher resolution obtained reveals previously unresolved spectral features of W(CO)6. The spectrum shows two higher-energy bands (in the energy ranges of 7.22-8.12 eV and 8.15-9.05 eV), one of them with clear vibrational structure, and a few lower-energy shoulders in addition to a couple of lower-energy metal-to-ligand charge-transfer (MLCT) bands reported in the literature before...
2017: Beilstein Journal of Nanotechnology
Jozef Lengyel, Peter Papp, Štefan Matejčík, Jaroslav Kočišek, Michal Fárník, Juraj Fedor
In this work, we probe anion production upon electron interaction with Fe(CO)5 clusters using two complementary cluster-beam setups. We have identified two mechanisms that lead to synthesis of complex anions with mixed Fe/CO composition. These two mechanisms are operative in distinct electron energy ranges. It is shown that the elementary decomposition mechanism that has received perhaps the most attention in recent years (i.e., dissociative electron attachment at energies close to 0 eV) becomes suppressed upon increasing aggregation of iron pentacarbonyl...
2017: Beilstein Journal of Nanotechnology
Christian Apostoli, Giovanni Giusti, Jacopo Ciccoianni, Gabriele Riva, Rosario Capozza, Rosalie Laure Woulaché, Andrea Vanossi, Emanuele Panizon, Nicola Manini
We introduce and study a minimal 1D model for the simulation of dynamic friction and dissipation at the atomic scale. This model consists of a point mass (slider) that moves over and interacts weakly with a linear chain of particles interconnected by springs, representing a crystalline substrate. This interaction converts a part of the kinetic energy of the slider into phonon waves in the substrate. As a result, the slider experiences a friction force. As a function of the slider speed, we observe dissipation peaks at specific values of the slider speed, whose nature we understand by means of a Fourier analysis of the excited phonon modes...
2017: Beilstein Journal of Nanotechnology
Takashi Yatsui, Hiroshi Saito, Katsuyuki Nobusada
The realization of flat surfaces on the angstrom scale is required in advanced devices to avoid loss due to carrier (electron and/or photon) scattering. In this work, we have developed a new surface flattening method that involves near-field etching, where optical near-fields (ONFs) act to dissociate the molecules. ONFs selectively generated at the apex of protrusions on the surface selectively etch the protrusions. To confirm the selective etching of the nanoscale structure, we compared near-field etching using both gas molecules and ions in liquid phase...
2017: Beilstein Journal of Nanotechnology
Alicja Mikolajczyk, Natalia Sizochenko, Ewa Mulkiewicz, Anna Malankowska, Michal Nischk, Przemyslaw Jurczak, Seishiro Hirano, Grzegorz Nowaczyk, Adriana Zaleska-Medynska, Jerzy Leszczynski, Agnieszka Gajewicz, Tomasz Puzyn
Titania-supported palladium, gold and bimetallic nanoparticles (second-generation nanoparticles) demonstrate promising photocatalytic properties. However, due to unusual reactivity, second-generation nanoparticles can be hazardous for living organisms. Considering the ever-growing number of new types of nanoparticles that can potentially contaminate the environment, a determination of their toxicity is extremely important. The main aim of presented study was to investigate the cytotoxic effect of surface modified TiO2-based nanoparticles, to model their quantitative nanostructure-toxicity relationships and to reveal the toxicity mechanism...
2017: Beilstein Journal of Nanotechnology
Krešimir Salamon, Maja Buljan, Iva Šarić, Mladen Petravić, Sigrid Bernstorff
Tantalum nitride nanoparticles (NPs) and cubic bixbyite-type Ta2N3 nanocrystals (NCs) were grown in (Ta-N+Al2O3)/Al2O3 periodic multilayers (MLs) after thermal treatment. The MLs were prepared by magnetron deposition at room temperature and characterized using grazing incidence small-angle X-ray scattering (GISAXS), X-ray reflectivity (XRR), grazing incidence X-ray diffraction (GIXRD), secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS). We found amorphous tantalum nitride NPs at 600-800 °C, with a high degree of ordering along the surface normal and short-range ordering within the layers containing tantalum (metallic layers)...
2017: Beilstein Journal of Nanotechnology
Dédalo Sanz-Hernández, Amalio Fernández-Pacheco
In this work, the continuum model for focused electron beam induced deposition (FEBID) is generalized to account for multilayer adsorption processes. Two types of adsorption energies, describing both physisorption and spontaneous chemisorption, are included. Steady state solutions under no diffusion are investigated and compared under a wide range of conditions. The different growth regimes observed are fully explained by relative changes in FEBID characteristic frequencies. Additionally, we present a set of FEBID frequency maps where growth rate and surface coverage are plotted as a function of characteristic timescales...
2017: Beilstein Journal of Nanotechnology
Nguyen T N Ha, Thiruvancheril G Gopakumar, Nguyen D C Yen, Carola Mende, Lars Smykalla, Maik Schlesinger, Roy Buschbeck, Tobias Rüffer, Heinrich Lang, Michael Mehring, Michael Hietschold
A chemical reaction (esterification) within a molecular monolayer at the liquid-solid interface without any catalyst was studied using ambient scanning tunneling microscopy. The monolayer consisted of a regular array of two species, an organic acid (trimesic acid) and an alcohol (undecan-1-ol or decan-1-ol), coadsorbed out of a solution of the acid within the alcohol at the interface of highly oriented pyrolytic graphite (HOPG) (0001) substrate. The monoester was observed promptly after reaching a threshold either related to the increased packing density of the adsorbate layer (which can be controlled by the concentration of the trimesic acid within the alcoholic solution via sonication or extended stirring) or by reaching a threshold with regards to the deposition temperature...
2017: Beilstein Journal of Nanotechnology
Perumal Kannappan, Nabiha Ben Sedrine, Jennifer P Teixeira, Maria R Soares, Bruno P Falcão, Maria R Correia, Nestor Cifuentes, Emilson R Viana, Marcus V B Moreira, Geraldo M Ribeiro, Alfredo G de Oliveira, Juan C González, Joaquim P Leitão
Mg doping of GaAs nanowires has been established as a viable alternative to Be doping in order to achieve p-type electrical conductivity. Although reports on the optical properties are available, few reports exist about the physical properties of intermediate-to-high Mg doping in GaAs nanowires grown by molecular beam epitaxy (MBE) on GaAs(111)B and Si(111) substrates. In this work, we address this topic and present further understanding on the fundamental aspects. As the Mg doping was increased, structural and optical investigations revealed: i) a lower influence of the polytypic nature of the GaAs nanowires on their electronic structure; ii) a considerable reduction of the density of vertical nanowires, which is almost null for growth on Si(111); iii) the occurrence of a higher WZ phase fraction, in particular for growth on Si(111); iv) an increase of the activation energy to release the less bound carrier in the radiative state from nanowires grown on GaAs(111)B; and v) a higher influence of defects on the activation of nonradiative de-excitation channels in the case of nanowires only grown on Si(111)...
2017: Beilstein Journal of Nanotechnology
Jilin Wang, Hejie Liao, Yuchun Ji, Fei Long, Yunle Gu, Zhengguang Zou, Weimin Wang, Zhengyi Fu
In this work, a reaction coupling self-propagating high-temperature synthesis (RC-SHS) method was developed for the in situ controlled synthesis of novel, high activity TiB2/(TiB2-TiN) hierarchical/heterostructured nanocomposites using TiO2, Mg, B2O3, KBH4 and NH4NO3 as raw materials. The as-synthesized samples were characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray energy dispersive spectroscopy (EDX), transition electron microscopy (TEM), high-resolution TEM (HRTEM) and selected-area electron diffraction (SAED)...
2017: Beilstein Journal of Nanotechnology
Soraya Sangiao, César Magén, Darius Mofakhami, Grégoire de Loubens, José María De Teresa
In this work, we present a detailed investigation of the magnetic properties of cobalt nanospheres grown on cantilever tips by focused electron beam induced deposition (FEBID). The cantilevers are extremely soft and the cobalt nanospheres are optimized for magnetic resonance force microscopy (MRFM) experiments, which implies that the cobalt nanospheres must be as small as possible while bearing high saturation magnetization. It was found that the cobalt content and the corresponding saturation magnetization of the nanospheres decrease for nanosphere diameters less than 300 nm...
2017: Beilstein Journal of Nanotechnology
Torsten Hahn, Tim Ludwig, Carsten Timm, Jens Kortus
The great potential of organic heterostructures for organic device applications is exemplified by the targeted engineering of the electronic properties of phthalocyanine-based systems. The transport properties of two different phthalocyanine systems, a pure copper phthalocyanine (CoPc) and a flourinated copper phthalocyanine-manganese phthalocyanine (F16CoPc/MnPc) heterostructure, are investigated by means of density functional theory (DFT) and the non-equilibrium Green's function (NEGF) approach. Furthermore, a master-equation-based approach is used to include electronic correlations beyond the mean-field-type approximation of DFT...
2017: Beilstein Journal of Nanotechnology
Bartosz Bartosewicz, Marta Michalska-Domańska, Malwina Liszewska, Dariusz Zasada, Bartłomiej J Jankiewicz
Core-shell nanostructures have found applications in many fields, including surface enhanced spectroscopy, catalysis and solar cells. Titania-coated noble metal nanoparticles, which combine the surface plasmon resonance properties of the core and the photoactivity of the shell, have great potential for these applications. However, the controllable synthesis of such nanostructures remains a challenge due to the high reactivity of titania precursors. Hence, a simple titania coating method that would allow better control over the shell formation is desired...
2017: Beilstein Journal of Nanotechnology
Alfredo J Diaz, Hanaul Noh, Tobias Meier, Santiago D Solares
Bioinspired design has been central in the development of hierarchical nanocomposites. Particularly, the nacre-mimetic brick-and-mortar structure has shown excellent mechanical properties, as well as gas-barrier properties and optical transparency. Along with these intrinsic properties, the layered structure has also been utilized in sensing devices. Here we extend the multifunctionality of nacre-mimetics by designing an optically transparent and electron conductive coating based on PEDOT:PSS and nanoclays Laponite RD and Cloisite Na(+)...
2017: Beilstein Journal of Nanotechnology
Giuseppe Foti, Héctor Vázquez
We study the role of an NH2 adsorbate on the current-induced heating and cooling of a neighboring carbene-based molecular circuit. We use first-principles methods of inelastic tunneling transport based on density functional theory and non-equilibrium Green's functions to calculate the rates of emission and absorbtion of vibrations by tunneling electrons, the population of vibrational modes and the energy stored in them. We find that the charge rearrangement resulting from the adsorbate gates the carbene electronic structure and reduces the density of carbene states near the Fermi level as a function of bias...
2017: Beilstein Journal of Nanotechnology
Colin K Curtis, Antonin Marek, Alex I Smirnov, Jacqueline Krim
This article reports a comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively (hydroxylated) or negatively (carboxylated) charged nanodiamonds (ND). Immersion in -ND suspensions resulted in a decrease in the macroscopic friction coefficients to values in the range 0.05-0.1 for both stainless steel and alumina, while +ND suspensions yielded an increase in friction for stainless steel contacts but little to no increase for alumina contacts...
2017: Beilstein Journal of Nanotechnology
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