Distinguishing magnetic and electrostatic interactions by a Kelvin probe force microscopy–magnetic force microscopy combination

• Miriam Jaafar,
• Oscar Iglesias-Freire,
• Luis Serrano-Ramón,
• Manuel Ricardo Ibarra,
• Jose Maria de Teresa and
• Agustina Asenjo

Beilstein J. Nanotechnol. 2011, 2, 552–560, doi:10.3762/bjnano.2.59

• the topography of organic and inorganic materials and to study chemical (composition), mechanical (including friction and stiffness, etc.), electrical (surface potential, work function), magnetic (domain structure) or biological (specific recognition) properties. A priori, the unknown contribution of

Tip-enhanced Raman spectroscopic imaging of patterned thiol monolayers

• Johannes Stadler,
• Thomas Schmid,
• Lothar Opilik,
• Phillip Kuhn,
• Petra S. Dittrich and
• Renato Zenobi

Beilstein J. Nanotechnol. 2011, 2, 509–515, doi:10.3762/bjnano.2.55

• properties (height, friction). One possible but very tedious way to distinguish the two thiols would have been to use high resolution STM (which is usually size limited to the nanometer range) to search for typical molecular patterns in the SAM structure. However, both thiols can assemble in several

Superhydrophobic surfaces of the water bug Notonecta glauca: a model for friction reduction and air retention

• Petra Ditsche-Kuru,
• Erik S. Schneider,
• Jan-Erik Melskotte,
• Martin Brede,
• Alfred Leder and
• Wilhelm Barthlott

Beilstein J. Nanotechnol. 2011, 2, 137–144, doi:10.3762/bjnano.2.17

• ecological interest because an air film can reduce friction of solid bodies sliding through the water. This opens perspectives for biomimetic applications such as low friction fluid transport or friction reduction on ship hulls. For such applications the durability of the air film is most important. While

• relevant for this outstanding ability. Besides high air film persistence, the observation of a considerable fluid velocity directly at the air–water interface indicates the ability to reduce friction significantly. The combination of these two abilities makes these hierarchically structured surfaces

• extremely interesting as a biomimetic model for low friction fluid transport or drag reduction on ship hulls. Keywords: air film; aquatic insects; backswimmer; drag reduction; superhydrophobic surfaces; Introduction Superhydrophobic surfaces are of great economic interest because of their amazing

Manipulation of gold colloidal nanoparticles with atomic force microscopy in dynamic mode: influence of particle–substrate chemistry and morphology, and of operating conditions

• Samer Darwich,
• Karine Mougin,
• Akshata Rao,
• Enrico Gnecco,
• Shrisudersan Jayaraman and
• Hamidou Haidara

Beilstein J. Nanotechnol. 2011, 2, 85–98, doi:10.3762/bjnano.2.10

• microscopy techniques and quantitative information on interfacial friction was extracted from the lateral manipulation of these nanoparticles [17]. These particles were first pushed on a graphite surface by the AFM tips and then manipulated by placing the AFM tip on top of the particles. Above a certain

• lateral force threshold, particle sliding was observed, which has allowed the transition from static to kinetic friction to be quantified [18]. A compromise between the contact and non-contact AFM techniques is the intermittent mode, the so called tapping mode. In this mode the phase shift of the

• of the dynamical processes occurring during manipulation, i.e., collisions between probing tips and particles, friction between particles and substrates, electrostatic interactions among all of them, etc. For this reason, colloidal particles have appeared as model nano-objects because they can be

Biomimetics inspired surfaces for drag reduction and oleophobicity/philicity

• Bharat Bhushan

Beilstein J. Nanotechnol. 2011, 2, 66–84, doi:10.3762/bjnano.2.9

• the flow velocity obtained from flow rate Q divided by cross section area of the channel, and f is the friction factor which specifies the loss in pressure required to impel a flow over the surface or through the channel. The friction factor is generally a function of Reynolds number, surface

• roughness, and the geometry of the surface. DH is the hydraulic diameter which is proportional to four times the flow area divided by the perimeter of the surface containing the flow. For the rectangular channel, the hydraulic diameter is The friction factor for laminar flow is inversely proportional to the

• with flow velocity. k is the friction coefficient which can be found by the solution of Poisson’s equation over the cross section as [55] From Equation 5, the friction coefficient is dependent only on the shapes of the cross section and independent of the surface roughness. To improve the calculation

Switching adhesion forces by crossing the metal–insulator transition in Magnéli-type vanadium oxide crystals

• Bert Stegemann,
• Matthias Klemm,
• Siegfried Horn and
• Mathias Woydt

Beilstein J. Nanotechnol. 2011, 2, 59–65, doi:10.3762/bjnano.2.8

• integrity, allows for relating frictional and electronic material properties at the nano scale. This behavior makes the vanadium Magnéli phases interesting candidates for technology, e.g., as intelligent devices or coatings where switching of adhesion or friction is desired. Keywords: adhesion force

• and micro-electro-mechanical systems (MEMS). In this context, a great technological challenge in advancing miniaturization is to overcome the strong adhesive attractions between nanoscopic tribo-elements in order to realize technical systems with low friction [12][13]. The atomic force microscope (AFM

• applications where switching of adhesion or friction is desired, such as intelligent devices or coatings. At the nanoscale, these adhesion measurements displayed a lower adhesion force in the metallic state than in the non-metallic, ceramic state, which is in contrast to the macroscopic experience in tribology

Review of "Contact Mechanics and Friction: Physical Principles and Applications" by Valentin L. Popov

• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2011, 2, 57–58, doi:10.3762/bjnano.2.7

• Stanislav N. Gorb Department of Functional Morphology and Biomechanics, Zoological Institute at the University of Kiel, Am Botanischen Garten 1–9, D-24098 Kiel, Germany 10.3762/bjnano.2.7 Keywords: adhesion; capillarity; contact mechanics; continuum mechanics; friction; lubrication; materials

• science; structural mechanics; system dynamics; tribology; Popov, V. L. Contact Mechanics and Friction: Physical Principles and Applications, 1st ed. Springer-Verlag: Berlin, Heidelberg, 2010. XV, 362 pages, ISBN 978-3-642-10802-0 (Print), 978-3-642-10803-7 (Online). doi:10.1007/978-3-642-10803-7 The

• book “Contact Mechanics and Friction: Physical Principles and Applications” is written by a theoretical physicist but from the point of view of an engineer. It covers an amazingly broad spectrum of topics ranging from atomic scale friction, continuum and structural mechanics, materials science

Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

• Thomas König,
• Georg H. Simon,
• Lars Heinke,
• Leonid Lichtenstein and
• Markus Heyde

Beilstein J. Nanotechnol. 2011, 2, 1–14, doi:10.3762/bjnano.2.1

• quantum mechanics [10][11]. Furthermore magnetic forces, friction forces, capillary forces etc. can in principle occur in NC-AFM. These forces are not relevant in this paper, since, e.g., a magnetic tip is necessary to detect magnetic forces, or non conservative forces have to be measured to determine

• friction forces. The forces relevant in this work are described below. Coulomb forces are a result of interacting charges and can be stronger than most chemical binding forces [9]. The Coulomb potential ECoulomb between two charges Q1 and Q2 is given by where ε0 is the permittivity constant, ζ is the

Tip-sample interactions on graphite studied using the wavelet transform

• Giovanna Malegori and
• Gabriele Ferrini

Beilstein J. Nanotechnol. 2010, 1, 172–181, doi:10.3762/bjnano.1.21

• spectrum. This thermal force induces cantilever displacements from the equilibrium position, that show a marked amplitude enhancement in correspondence of the flexural eigenfrequencies. Since the cantilever is subjected also to dissipative friction forces, the amplitude response of the cantilever around a

The description of friction of silicon MEMS with surface roughness: virtues and limitations of a stochastic Prandtl–Tomlinson model and the simulation of vibration-induced friction reduction

• W. Merlijn van Spengen,
• Viviane Turq and
• Joost W. M. Frenken

Beilstein J. Nanotechnol. 2010, 1, 163–171, doi:10.3762/bjnano.1.20

• cedex 9, France Leiden University, LION, Niels Bohrweg 2, 2333CA, Leiden, The Netherlands 10.3762/bjnano.1.20 Abstract We have replaced the periodic Prandtl–Tomlinson model with an atomic-scale friction model with a random roughness term describing the surface roughness of micro-electromechanical

• systems (MEMS) devices with sliding surfaces. This new model is shown to exhibit the same features as previously reported experimental MEMS friction loop data. The correlation function of the surface roughness is shown to play a critical role in the modelling. It is experimentally obtained by probing the

• sidewall surfaces of a MEMS device flipped upright in on-chip hinges with an AFM (atomic force microscope). The addition of a modulation term to the model allows us to also simulate the effect of vibration-induced friction reduction (normal-force modulation), as a function of both vibration amplitude and

A collisional model for AFM manipulation of rigid nanoparticles

• Enrico Gnecco

Beilstein J. Nanotechnol. 2010, 1, 158–162, doi:10.3762/bjnano.1.19

• and r' is the first derivative of r(φ) with respect to φ (Figure 1b). In contact mode the tip hits the particle along the x direction and the force F can be oriented as in tapping mode only if the static friction force f between tip and particle is high enough to prevent sliding along the island profile

• (Figure 1c). Assuming that friction between island and substrate is also high enough to prevent any slippage of the island after a collision with the tip, Equation 1 and Equation 2 can be averaged over the short collision time Δt (in the order of 1/ f , with f ~ 105 Hz being the oscillation frequency of

• , where a ‘mean free path’ d of the nanoparticles was introduced. If the friction force between particle and substrate decreases, and consequently the distance d increases, then the pathway of the nanoparticle fluctuates more and more, but the form of the function θ(b) remains essentially unchanged [8

Scanning probe microscopy and related methods

• Ernst Meyer

Beilstein J. Nanotechnol. 2010, 1, 155–157, doi:10.3762/bjnano.1.18

• . Scanning probe microscopy (SPM) uses probing tips to map properties, such as topography, local adhesive forces, elasticity, friction or magnetic properties. In the emerging fields of nanoscience and nanotechnology these types of microscopes help to characterize the nanoworld. In addition, local probes can

• molecules on surfaces. AFM has evolved considerably in the last few years, where new operation modes, such as non-contact force microscopy (nc-AFM), Kelvin probe force microscopy (KPFM) or friction force microscopy (FFM), were developed. One main focus is the high resolution capabilities of nc-AFM, which

• gives insight into fascinating phenomena, such as metal-superconductor transitions or metal-insulator transitions. Another important development is related to nanomechanics, where phenomena, such as friction, wear, elasticity and plasticity are studied on an atomic scale. Atomic friction has been

Review and outlook: from single nanoparticles to self-assembled monolayers and granular GMR sensors

• Alexander Weddemann,
• Inga Ennen,
• Anna Regtmeier,
• Camelia Albon,
• Annalena Wolff,
• Katrin Eckstädt,
• Nadine Mill,
• Michael K.-H. Peter,
• Jochen Mattay,
• Carolin Plattner,
• Norbert Sewald and
• Andreas Hütten

Beilstein J. Nanotechnol. 2010, 1, 75–93, doi:10.3762/bjnano.1.10

• order [49]. Additionally, friction and shear forces can arise between the particles on the one hand and between particles and substrate on the other hand [57][58]. In the latter case, the forces strongly depend on the surface properties such as structure and roughness. Thus, the choice of substrate is