Laser-processed antiadhesive bionic combs for handling nanofibers inspired by nanostructures on the legs of cribellate spiders

• Sebastian Lifka,
• Kristóf Harsányi,
• Erich Baumgartner,
• Lukas Pichler,
• Dariya Baiko,
• Karsten Wasmuth,
• Johannes Heitz,
• Marco Meyer,
• Anna-Christin Joel,
• Jörn Bonse and
• Werner Baumgartner

Beilstein J. Nanotechnol. 2022, 13, 1268–1283, doi:10.3762/bjnano.13.105

• because nanofibers strongly adhere to any surface due to van der Waals forces [9]. For a cylindrical fiber with radius R interacting with the plane surface of a semi-infinite body, the energy per unit length due to van der Waals interaction is given as [9]: with the Hamaker constant AH, which is according

• parameters and some constants such as the Hamaker constant and the elastic modulus of the fiber. These free parameters are the amplitude a and the spatial period Λ = 2λ of the sinusoidal surface, as well as the bending stiffness and the radius of the fiber in the case of S = 0. While finding the minimum of

• the total energy is cumbersome when trying to find an analytical solution, the slope of the total energy can be calculated as Thus, if the fiber will adhere well as the energy directly decreases from x0 = 0. The results are shown in Figure 4 for E = 80 MPa, a Hamaker constant AH = 7.5·10−2, and for

Colloidal particle aggregation: mechanism of assembly studied via constructal theory modeling

• Scott C. Bukosky,
• Sukrith Dev,
• Monica S. Allen and
• Jeffery W. Allen

Beilstein J. Nanotechnol. 2021, 12, 413–423, doi:10.3762/bjnano.12.33

• dielectric constant, respectively. Conversely, the attractive van der Waals force is given by [14]: where the characteristic energy scale is set by the Hamaker constant, A. It is noted that Equation 1 and Equation 2 assume spherical particles of equal radius and a sufficiently small separation distance (a

Analysis of catalyst surface wetting: the early stage of epitaxial germanium nanowire growth

• Owen C. Ernst,
• Felix Lange,
• David Uebel,
• Thomas Teubner and
• Torsten Boeck

Beilstein J. Nanotechnol. 2020, 11, 1371–1380, doi:10.3762/bjnano.11.121

• leads to a wide spectrum of different values. Furthermore, only the nonretarded interactions are considered; however, at higher thicknesses (>10 nm) the retarded interactions become more relevant. Nevertheless, all essential effects and values occur for thickness values below 1 nm. Since the Hamaker

• constant is a critical value for the models shown here, its wide range can lead to difficulties in obtaining reliable values for the free energy of a system, especially for the fully theoretical model, which focuses on van der Waals interactions. However, the theoretical predictions for gold on silicon fit

Influence of the magnetic nanoparticle coating on the magnetic relaxation time

• Mihaela Osaci and
• Matteo Cacciola

Beilstein J. Nanotechnol. 2020, 11, 1207–1216, doi:10.3762/bjnano.11.105

• , we considered the case in which a colloid is electrostatically stabilised. The system is composed of water-dispersed spherical magnetite nanoparticles whose sizes follow a lognormal distribution. The Hamaker constant for magnetite in water is given as a reference value [20]. The system parameter

Stochastic excitation for high-resolution atomic force acoustic microscopy imaging: a system theory approach

• Edgar Cruz Valeriano,
• José Juan Gervacio Arciniega,
• Christian Iván Enriquez Flores,
• Susana Meraz Dávila,
• Joel Moreno Palmerin,
• Martín Adelaido Hernández Landaverde,
• Yuri Lizbeth Chipatecua Godoy,
• Aime Margarita Gutiérrez Peralta,
• Rafael Ramírez Bon and
• José Martín Yañez Limón

Beilstein J. Nanotechnol. 2020, 11, 703–716, doi:10.3762/bjnano.11.58

• perpendicular to the cantilever and f(t) is the interaction force between the cantilever and the surface expressed by the Derjaguin–Muller–Toporov (DMT) model [1] as Here, H is the Hamaker constant, R is the tip radius, E* is the reduced elastic modulus between the tip and the sample, a0 is the interatomic

Evolution of Ag nanostructures created from thin films: UV–vis absorption and its theoretical predictions

• Robert Kozioł,
• Marcin Łapiński,
• Paweł Syty,
• Damian Koszelow,
• Wojciech Sadowski,
• Józef E. Sienkiewicz and
• Barbara Kościelska

Beilstein J. Nanotechnol. 2020, 11, 494–507, doi:10.3762/bjnano.11.40

• type of dewetting [19][20][21]. If dewetting is of the spinodal type, then the above parameters are related in the following way: where f(θ) is a geometric factor based on the particle contact angle θ, γ is the surface tension of the metal and A is the Hamaker constant. This is valid for the

Current measurements in the intermittent-contact mode of atomic force microscopy using the Fourier method: a feasibility analysis

• Berkin Uluutku and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2020, 11, 453–465, doi:10.3762/bjnano.11.37

• with a flat surface [42]. The imaging parameters are selected to resemble day-to-day large-amplitude experiments. The cantilever properties are similar to those of commercial cantilevers (e.g., BudgetSensors, ElectriMulti75-G conductively coated KPFM cantilevers). The Hamaker constant is chosen within

In situ characterization of nanoscale contaminations adsorbed in air using atomic force microscopy

• Jesús S. Lacasa,
• Lisa Almonte and
• Jaime Colchero

Beilstein J. Nanotechnol. 2018, 9, 2925–2935, doi:10.3762/bjnano.9.271

• function of tip–sample voltage and tip–sample distance, we are able to determine the contact potential, the Hamaker constant and the effective thickness of the dielectric layer within the tip–sample system. All these properties depend strongly on the contamination within the tip–sample system. We propose

• to access the state of contamination of real surfaces under ambient conditions using advanced atomic force microscopy techniques. Keywords: atomic force microscopy; cantilever; contact potential; electrostatic forces; force spectroscopy; Hamaker constant; Kelvin probe microscopy; surface

• ) = πε0R/d2. Then, the total frequency-shift induced by the tip–sample interaction is: where the first term containing the Hamaker constant A describes the van der Waals interaction and the second term describes the electrostatic interaction. We note that the chemical composition of the sample will

The role of ligands in coinage-metal nanoparticles for electronics

• Ioannis Kanelidis and
• Tobias Kraus

Beilstein J. Nanotechnol. 2017, 8, 2625–2639, doi:10.3762/bjnano.8.263

• , and only remain stable in dispersion if ligands reduce their attractive interactions [85]. The lower Hamaker constant of the ligand shell, its entropic behavior, and its ω-functionalities can make nanoparticles colloidally stable in organic or aqueous environments. Ligands such as citric acid [86

Material property analytical relations for the case of an AFM probe tapping a viscoelastic surface containing multiple characteristic times

• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2017, 8, 2230–2244, doi:10.3762/bjnano.8.223

• excitation suddenly imposed during the impact. The third term is the relaxation modulus, and the fourth term is the adhesive portion of the van der Waals (vdW) interaction, in which HA is the Hamaker constant, R is the radius of the cylindrical punch, and a0 is the interatomic distance (ca. 0.2 nm) [39]. In

Functional dependence of resonant harmonics on nanomechanical parameters in dynamic mode atomic force microscopy

• Federico Gramazio,
• Matteo Lorenzoni,
• Francesc Pérez-Murano,
• Enrique Rull Trinidad,
• Urs Staufer and
• Jordi Fraxedas

Beilstein J. Nanotechnol. 2017, 8, 883–891, doi:10.3762/bjnano.8.90

• such parameters [6][7][8][9][10]. The DMT model, which will be used in this work, has the following expression in the repulsive regime: where H is the Hamaker constant, a0 the intermolecular distance, d the tip–sample gap (related to z) and E* the reduced Young modulus, which includes the contribution

Measuring adhesion on rough surfaces using atomic force microscopy with a liquid probe

• Juan V. Escobar,
• Cristina Garza and
• Rolando Castillo

Beilstein J. Nanotechnol. 2017, 8, 813–825, doi:10.3762/bjnano.8.84

• ., atomic contact, using Wadh = −AR1R2/6D(R1 + Rs) [37]. Here, A is the Hamaker constant that can be evaluated with the same method as the interaction energy between two flat surfaces of unit area, at the same separation D, using the Dupré equation w = A/12πD2 = γ(1 + cos θc). For this calculation, we use

Correlative infrared nanospectroscopic and nanomechanical imaging of block copolymer microdomains

• Benjamin Pollard and
• Markus B. Raschke

Beilstein J. Nanotechnol. 2016, 7, 605–612, doi:10.3762/bjnano.7.53

• or capillary forces). It can reflect variations in the Hamaker constant of the van der Waals interaction, surface charges, or hydrophilicity [32]. It has been observed in PS-b-PMMA that PS preferentially adsorbs onto a gold surface compared to PMMA [33]. Thus, the higher attractive forces over PS

A simple and efficient quasi 3-dimensional viscoelastic model and software for simulation of tapping-mode atomic force microscopy

• Santiago D. Solares

Beilstein J. Nanotechnol. 2015, 6, 2233–2241, doi:10.3762/bjnano.6.229

• extract properties such as the Young’s modulus, which describes the bulk stress–strain relation of the material, or the Hamaker constant, which describes the dispersion forces between the tip and the sample. In the case of a viscoelastic surface the extraction of material ‘properties’ is difficult for a

Optimization of phase contrast in bimodal amplitude modulation AFM

• Mehrnoosh Damircheli,
• Amir F. Payam and
• Ricardo Garcia

Beilstein J. Nanotechnol. 2015, 6, 1072–1081, doi:10.3762/bjnano.6.108

• tip–surface force (Hamaker constant and Young modulus) and the operational values of the microscope are summarized in Table 1 and Table 2. For trimodal AFM simulations we have used the parameters shown in Table 3. To minimize some complex non-linear dynamic effects we restrict our study to situations

• has a higher Hamaker constant. The power dissipated by the 2nd mode also shows a maximum with A1/A01 near 0.2 (Figure 4c). A discussion about the energy transfer among different modes is presented by Solares and co-workers [48]. The data plotted in Figure 3 and Figure 4 has been obtained by using the

• first and the second modes. Bimodal AM in the attractive regime. (a) Phase shift dependence on the amplitude ratio of the first mode for different values of A02. The value of the Hamaker constant is set for the Au–air–Si interface. (b) Phase shift dependence on the amplitude ratio of the first mode for

Capillary and van der Waals interactions on CaF₂ crystals from amplitude modulation AFM force reconstruction profiles under ambient conditions

• Annalisa Calò,
• Oriol Vidal Robles,
• Sergio Santos and
• Albert Verdaguer

Beilstein J. Nanotechnol. 2015, 6, 809–819, doi:10.3762/bjnano.6.84

• van der Waals interactions used in Equation 7, we estimated a value for the Hamaker constant of (7.3 ± 0.4) · 10−20 J. Although this value has not to be taken as an accurate measurement of the Hamaker constant, it is in the range of the experimental and theoretical values reported in the literature

• for: 1) One where van der Waals (vdW) forces are present in the long range and repulsive forces are present in the short range. Long-range conservative vdW forces have been modeled, as it is customary in dynamic AFM theory [14][27][30][51], as: where H is the Hamaker constant. Viscosity in the short

• been considered also and modeled simply as a difference in the Hamaker constant H during tip retraction relative to tip approach. In particular, Hretraction = 1.5·Happroach. This term accounts for long-range dissipation in Figure 3b and could be identified with dissipation due to contact between the

Dynamic force microscopy simulator (dForce): A tool for planning and understanding tapping and bimodal AFM experiments

• Horacio V. Guzman,
• Pablo D. Garcia and
• Ricardo Garcia

Beilstein J. Nanotechnol. 2015, 6, 369–379, doi:10.3762/bjnano.6.36

• resulting expressions. van der Waals The van der Waals interaction between a sphere and a half-space is calculated by [46] where Rt is the tip radius, H is the Hamaker constant, d is the distance between the tip’s apex the sample surface and a0 is the intermolecular distance (0.165 nm). Derjaguin–Landau

• mode is the observable used in heterogeneous samples to separate regions of different material properties. Figure 7 shows the dependence of the phase shift as a function of the set-point amplitude and the material properties (changes in the Hamaker constant). The phase shift (attractive regime) has a

Modeling viscoelasticity through spring–dashpot models in intermittent-contact atomic force microscopy

• Enrique A. López-Guerra and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 2149–2163, doi:10.3762/bjnano.5.224

• tip modulus (Et) of 150 GPa, Poisson’s ratio of tip and sample (υt and υs, respectively) of 0.3, tip radius of curvature (R) of 10 nm, Hamaker constant of 2 × 10−19 J. For (a) a viscosity (η) value of 400 N·s/m2 was used. For (b) a dissipation coefficient (γ0) of 3 × 10−7 kg/s, and a characteristic

Dynamic calibration of higher eigenmode parameters of a cantilever in atomic force microscopy by using tip–surface interactions

• Stanislav S. Borysov,
• Daniel Forchheimer and
• David B. Haviland

Beilstein J. Nanotechnol. 2014, 5, 1899–1904, doi:10.3762/bjnano.5.200

• exponentially dependent on the tip position [36] where h is a reference height. Its conservative part, Fcon, has four phenomenological parameters: the intermolecular distance a0 = 0.3 nm, the Hamaker constant H = 7.1 × 10−20 J, the effective modulus E* = 1.0 GPa and the tip radius R = 10 nm. The dissipative

Probing viscoelastic surfaces with bimodal tapping-mode atomic force microscopy: Underlying physics and observables for a standard linear solid model

• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 1649–1663, doi:10.3762/bjnano.5.176

• cases as a SLS (Figure 1a), except for the result of Figure 1c, which uses the combination of a Hertzian contact model with a depth dependent dissipation constant [34][42]. Long-range attractive interactions were included for a tip radius of curvature of 10 nm and a Hamaker constant of 2 × 10−19 J. In

Multi-frequency tapping-mode atomic force microscopy beyond three eigenmodes in ambient air

• Santiago D. Solares,
• Sangmin An and
• Christian J. Long

Beilstein J. Nanotechnol. 2014, 5, 1637–1648, doi:10.3762/bjnano.5.175

• -range attractive interactions were included via the Hamaker equation [24] for a tip radius of curvature of 10 nm and a Hamaker constant of 2 × 10−9 J. Disclaimer Certain commercial equipment, instruments or materials are identified in this document. Such identification does not imply recommendation or

Trade-offs in sensitivity and sampling depth in bimodal atomic force microscopy and comparison to the trimodal case

• Babak Eslami,
• Daniel Ebeling and
• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 1144–1151, doi:10.3762/bjnano.5.125

• ] having force constants of 7.5 N/m for the two linear springs and a dashpot constant of 1 × 10−5 Ns/m. The long-range attractive interactions were included through the Hamaker equation [14] for a tip radius of curvature of 10 nm and a Hamaker constant of 2 × 10−19 J. (a) and (b) topography and phase

Direct observation of microcavitation in underwater adhesion of mushroom-shaped adhesive microstructure

• Lars Heepe,
• Alexander E. Kovalev and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 903–909, doi:10.3762/bjnano.5.103

• results we may consider the following two limiting cases in the underwater adhesion of MSAMS. In the first case, a thin water layer separates the glass–MSAMS contact. Then the van der Waals interaction strength, described by the Hamaker constant between glass and MSAMS, is expected to be reduced by about

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

• recently [19]. The VDW model might approximate the long-range van der Waals interactions in a way that Δγ reflects the Hamaker constant. Depending on the confined system in question, other effective interactions might be possible. However, all models represent the feature that surfaces repel upon close

Uncertainties in forces extracted from non-contact atomic force microscopy measurements by fitting of long-range background forces

• Adam Sweetman and
• Andrew Stannard

Beilstein J. Nanotechnol. 2014, 5, 386–393, doi:10.3762/bjnano.5.45

• + b)c + d to fit the long-range part of the curve (using the standard curve fitting toolbox in MATLAB), assuming the tip–surface configuration can be modelled as a simple geometric shape positioned above a plane. Here a is related to the Hamaker constant of the material and size of the tip, b