Dissipation signals due to lateral tip oscillations in FM-AFM

• Michael Klocke and
• Dietrich E. Wolf

Beilstein J. Nanotechnol. 2014, 5, 2048–2057, doi:10.3762/bjnano.5.213

• neglect this kind of coupling, as it is an intrinsic feature of the cantilever and should not be sensitive to the surface potential (we also neglect any kind of direct coupling between different lateral modes [22]). Based on this assumption, we present a simple two-dimensional model for surface-induced

Current state of laser synthesis of metal and alloy nanoparticles as ligand-free reference materials for nano-toxicological assays

• Christoph Rehbock,
• Jurij Jakobi,
• Lisa Gamrad,
• Selina van der Meer,
• Daniela Tiedemann,
• Ulrike Taylor,
• Wilfried Kues,
• Detlef Rath and
• Stephan Barcikowski

Beilstein J. Nanotechnol. 2014, 5, 1523–1541, doi:10.3762/bjnano.5.165

• a systematic evaluation of adverse effects of less noble metals and metal oxide nanoparticles [154], their applicability to AuAg alloys may still be possible. The driving forces in this context were identified to be the surface potential and oxidation state of the nanoparticles, both potentially

The study of surface wetting, nanobubbles and boundary slip with an applied voltage: A review

• Yunlu Pan,
• Bharat Bhushan and
• Xuezeng Zhao

Beilstein J. Nanotechnol. 2014, 5, 1042–1065, doi:10.3762/bjnano.5.117

• liquid ρe can be written as: Then the potential ψ can be expressed by the Poisson equation [88]: where ε is the relative dielectric constant of the liquid, ε0 is the permittivity of vacuum. The boundary conditions of Poisson equation are where ξ is the surface potential at the boundary, called zeta

Methods for rapid frequency-domain characterization of leakage currents in silicon nanowire-based field-effect transistors

• Tomi Roinila,
• Xiao Yu,
• Jarmo Verho,
• Tie Li,
• Pasi Kallio,
• Matti Vilkko,
• Anran Gao and
• Yuelin Wang

Beilstein J. Nanotechnol. 2014, 5, 964–972, doi:10.3762/bjnano.5.110

• , in which the back-gate contact is used to control the conductivity of the SiNW with the box layer. The molecules (detection targets) vary the surface potential of the transistor surface oxide. The leakage currents in those oxide layers affect the current between the source and drain. Recent studies

Single-asperity contact mechanics with positive and negative work of adhesion: Influence of finite-range interactions and a continuum description for the squeeze-out of wetting fluids

• Martin H. Müser

Beilstein J. Nanotechnol. 2014, 5, 419–437, doi:10.3762/bjnano.5.50

• potentials with zero slope at g = 0 make the results move toward the DMT limit. In contrast to the ac(FN) dependence, the normal displacement curve d(FN) predominantly depends on the Tabor coefficient. Now, all μT = 1 curves resemble each other closely, independent of the slope of the surface potential at

Effect of contaminations and surface preparation on the work function of single layer MoS₂

• Oliver Ochedowski,
• Kolyo Marinov,
• Nils Scheuschner,
• Artur Poloczek,
• Benedict Kleine Bussmann,
• Janina Maultzsch and
• Marika Schleberger

Beilstein J. Nanotechnol. 2014, 5, 291–297, doi:10.3762/bjnano.5.32

• caused by the processing on the surface potential of MoS2. It is shown that the charge transfer from the substrate is able to change the work function of MoS2 by about 40 meV. Our findings suggest two things. First, the necessity to properly clean devices after processing as contaminations have a great

• impact on the surface potential. Second, that by choosing appropriate materials the work function can be modified to reduce contact resistance. Keywords: KPFM; MoS2; NC-AFM; surface potential; work function; Introduction Due to their unique properties which can differ a lot compared to bulk materials

• and KPFM measurements the sample was introduced to the UHV system. Before the data collection the sample was heated in situ to 200 °C for 30 min to remove any adsorbates from ambience. In Figure 3a and Figure 3c the NC-AFM topography and the corresponding surface potential map are shown, respectively

The role of surface corrugation and tip oscillation in single-molecule manipulation with a non-contact atomic force microscope

• Christian Wagner,
• Norman Fournier,
• F. Stefan Tautz and
• Ruslan Temirov

Beilstein J. Nanotechnol. 2014, 5, 202–209, doi:10.3762/bjnano.5.22

• the sliding of the molecule across the corrugated surface potential. On the methodological side, the important message of this work is to demonstrate that the force-field modeling of single-molecule manipulation can be successful in explaining precise details of the NC-AFM junction mechanics. However

• result in the lower end of the molecule sliding through a corrugated surface potential during the lifting of the tip. The lateral displacement of the molecule over the corrugated surface will be induced by the retraction of the tip as well as by the vibration of the qPlus sensor. As a result, the

Noise performance of frequency modulation Kelvin force microscopy

• Heinrich Diesinger,
• Dominique Deresmes and
• Thierry Mélin

Beilstein J. Nanotechnol. 2014, 5, 1–18, doi:10.3762/bjnano.5.1

• and optimizing around randomly chosen key values. Keywords: dynamic; frequency noise; Kelvin force microscopy; noise performance; phase noise; thermal excitation; Introduction Surface potential imaging in combination with atomic force microscopy in ultrahigh vacuum is based on the measurement of

• the probe–sample capacity is used, it is expected to be more sensitive to the very extremity of the tip [4], or because the use of probes with an increased fundamental resonance frequency makes the use of higher harmonics for simultaneous surface potential imaging inaccessible to the bandwidth of the

• tip retraction at 3fc is −24 dB below the sum of the constant terms, or 6%. The constant tip retraction can be thought to be less troublesome because it introduces only an offset in the topography image while the retraction from varying surface potential introduces a real artifact. Nevertheless, it is

Routes to rupture and folding of graphene on rough 6H-SiC(0001) and their identification

• M. Temmen,
• O. Ochedowski,
• B. Kleine Bussmann,
• M. Schleberger,
• M. Reichling and
• T. R. J. Bollmann

Beilstein J. Nanotechnol. 2013, 4, 625–631, doi:10.3762/bjnano.4.69

• mechanically exfoliated under ambient conditions on 6H-SiC(0001) are modified by (i) swift heavy ion (SHI) irradiation, (ii) by a force microscope tip and (iii) by severe heating. The resulting surface topography and the surface potential are investigated with non-contact atomic force microscopy (NC-AFM) and

• region as the dashed box in Figure 3b after heating to 700 K. The onset of the heating effect is found at about 500 K. Discriminating graphene stackings by their surface potential Next, we investigate the graphene layer, its rupture, foldings and stacking in more detail by Kelvin compensated NC-AFM

Kelvin probe force microscopy of nanocrystalline TiO₂ photoelectrodes

• Alex Henning,
• Gino Günzburger,
• Res Jöhr,
• Yossi Rosenwaks,
• Biljana Bozic-Weber,
• Catherine E. Housecroft,
• Edwin C. Constable,
• Ernst Meyer and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2013, 4, 418–428, doi:10.3762/bjnano.4.49

• with a tunable illumination system. A comparison of the surface potentials for TiO2 photoelectrodes sensitized with two different dyes, i.e., the standard dye N719 and a copper(I) bis(imine) complex, reveals an inverse orientation of the surface dipole. A higher surface potential was determined for an

• N719 photoelectrode. The surface potential increase due to the surface dipole correlates with a higher DSC performance. Concluding from this, microscopic surface potential variations, attributed to the complex nanostructure of the photoelectrode, influence the DSC performance. For both bare and

• ]. Although a DSC photoelectrode consists of a nanostructured TiO2, there are few microscopic studies [17]. Surface photovoltage (SPV) spectroscopy is a non-destructive and sensitive method for determining surface potential changes upon illumination, identifying surface states, and extracting material

Probing three-dimensional surface force fields with atomic resolution: Measurement strategies, limitations, and artifact reduction

• Mehmet Z. Baykara,
• Omur E. Dagdeviren,
• Todd C. Schwendemann,
• Harry Mönig,
• Eric I. Altman and
• Udo D. Schwarz

Beilstein J. Nanotechnol. 2012, 3, 637–650, doi:10.3762/bjnano.3.73

• ) for most tip–sample distances (Figure 6a). At very close separations, however, the atomically sharp tip apex employed in the simulations experiences a larger attractive force on the site of the minima of the surface potential (the hollow sites). This force contrast flip causes a crossing of the ∆f(z

Drive-amplitude-modulation atomic force microscopy: From vacuum to liquids

• Miriam Jaafar,
• David Martínez-Martín,
• Mariano Cuenca,
• John Melcher,
• Arvind Raman and
• Julio Gómez-Herrero

Beilstein J. Nanotechnol. 2012, 3, 336–344, doi:10.3762/bjnano.3.38

• for obvious reasons: As the amplitude grows the tip finds the sample surface at a lower z-scanner position. When the tip approaches the surface it encounters a potential well that is the combination of the harmonic potential of the cantilever plus the surface potential. In order to maintain the

• oscillation we have to provide a total energy to the cantilever that is high enough that the tip is not trapped by the surface potential. Since the system is not conservative this total energy varies with time. The energy dissipated by a cantilever over one period in vacuum is, as a consequence of the tip

Dipole-driven self-organization of zwitterionic molecules on alkali halide surfaces

• Laurent Nony,
• Franck Bocquet,
• Franck Para,
• Frédéric Chérioux,
• Eric Duverger,
• Frank Palmino,
• Vincent Luzet and
• Christian Loppacher

Beilstein J. Nanotechnol. 2012, 3, 285–293, doi:10.3762/bjnano.3.32

• following one-dimensional model for the cases of KBr (i.e., 10 cmsps for 11 substrate distances) and NaCl (i.e., 9 cmsps for 11 substrate distances) along both molecular axis directions as depicted in Figure 4. First, we assume that the adsorption energy Eads varies laterally following the Madelung surface

• potential of the substrate, i.e., a sinusoidal potential, and we position the molecules according to the two coincidences (Figure 5a and Figure 5d). Along the short molecular axes, each molecular protrusion corresponds to an anchoring site (i.e., the dipolar end with the pyridine ring and its positive

Modeling noncontact atomic force microscopy resolution on corrugated surfaces

• Kristen M. Burson,
• Mahito Yamamoto and
• William G. Cullen

Beilstein J. Nanotechnol. 2012, 3, 230–237, doi:10.3762/bjnano.3.26

• obtaining this “point atom” potential, one can then integrate over the tip volume to obtain the tip–surface potential. We first obtain results for a flat surface with boundary at z = 0, initially for the “point atom” and then for a spherical tip body. This allows a check of the numerical integration scheme

• by comparison with analytical results. We then apply the method to a corrugated surface. As an intermediate result, we discuss the tip–surface potential and its z dependence since we find a different scaling from the sphere–plane result generally assumed. Finally, to simulate NC-AFM imaging, we

• tip–surface) is obtained pairwise by integration of this potential. 1 Atom–surface potential We first consider a “point atom” interacting with a flat, semi-infinite substrate with density ρS (number/volume). The integration may be written as As shown in [25], this has an analytic solution. For a

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

• scanning the surface. The surface potential, measured after annealing the crystal, was generally quite high, often in the range 4–8 V. Therefore, the voltage applied between the surface and the tip, Ubias, was monitored and adjusted regularly to minimize the electrostatic forces arising from the contact

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

• ↔trans switching have been demonstrated for SAMs. These include mechanical testing, as mentioned above, as well as changes in the local surface potential [13][14], UV–vis spectroscopy [10], wettability [15], and direct molecular-resolution imaging by scanning tunneling microscopy [10]. These methods vary

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

• ., they exhibit large surface potential differences causing heterogeneous electrostatic interaction between the tip and the sample that could be interpreted as a magnetic interaction. To distinguish clearly the origin of the tip–sample forces we propose to use a combination of Kelvin probe force

• 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

• based materials [10][11]. In general, these materials present low magnetic moment at room temperature. In addition, since the substrate and the nanomagnets present quite different electronic behavior, the sample can exhibit large surface potential differences, which cause heterogeneous electrostatic

Characterization of protein adsorption onto FePt nanoparticles using dual-focus fluorescence correlation spectroscopy

• Pauline Maffre,
• Karin Nienhaus,
• Faheem Amin,
• Wolfgang J. Parak and
• G. Ulrich Nienhaus

Beilstein J. Nanotechnol. 2011, 2, 374–383, doi:10.3762/bjnano.2.43

• . For apoA-I, there is only a weak area of positive surface potential (Figure 3b), consistent with the low affinity toward the NPs. For HSA binding to FePt NPs, we have previously reported a Hill coefficient n < 1 [11], which is indicative of anti-cooperative binding, meaning that the binding affinity

The role of the cantilever in Kelvin probe force microscopy measurements

• George Elias,
• Thilo Glatzel,
• Ernst Meyer,
• Alex Schwarzman,
• Amir Boag and
• Yossi Rosenwaks

Beilstein J. Nanotechnol. 2011, 2, 252–260, doi:10.3762/bjnano.2.29

• inhomogeneous sample surface potential. Both the probe and the sample were divided into boundary elements in order to calculate their surface charge density. Unlike our previous work [7], where the probe was divided into conical and spherical elements, here we used commercial software (MSC/Patran®) in order to

• the probe boundary elements divided by 2εo, and (d) the vector , which is a discrete representation of the surface potential, corresponding to a probe centered at r = (x,y,z). Matrices G, D, B and vector were previously defined in [7] and are explained again in the Appendix section. The probe–sample

• system was solved by dividing the mutual interactions into homogeneous and inhomogeneous parts. The homogeneous part represents a system with a probe above an infinite earthed plane, while the inhomogeneous part accounts for the contribution of the sample surface potential to the electrostatic force

Single-pass Kelvin force microscopy and dC/dZ measurements in the intermittent contact: applications to polymer materials

• Sergei Magonov and
• John Alexander

Beilstein J. Nanotechnol. 2011, 2, 15–27, doi:10.3762/bjnano.2.2

• interactions can be performed in the intermittent contact regime in different environments. Such combination provides sensitive detection of the surface potential and capacitance gradient with nanometer-scale spatial resolution as it was verified on self-assemblies of fluoroalkanes and a metal alloy. The KFM

• selective swelling of components. Keywords: atomic force microscopy; fluoroalkanes; Kelvin force microscopy; surface potential; Introduction Atomic force microscopy (AFM) applications include high-resolution imaging, probing of local materials properties and compositional mapping of heterogeneous

• enable measurements of electrical properties (surface potential, dielectric permittivity, capacitance, etc.) at a tip–sample junction. Here we will demonstrate that single-pass Kelvin force microscopy (KFM) studies based on sensing of an electrostatic force gradient can be performed in the intermittent

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

• . The simultaneously measured frequency shift Δf and tunneling current It give insight into the local surface potential as well as into the local electronic structure. The corresponding results of such an experiment are shown in Figure 7, where the tip scanned across an F0 defect. The three stacked