Tunable longitudinal modes in extended silver nanoparticle assemblies

• Serene S. Bayram,
• Klas Lindfors and
• Amy Szuchmacher Blum

Beilstein J. Nanotechnol. 2016, 7, 1219–1228, doi:10.3762/bjnano.7.113

• to transverse and longitudinal plasmon resonances, respectively (see numerical simulations and Figure 2). The red shift in the longitudinal plasmon is due to plasmonic coupling between extremely closely spaced particles enhanced by the short length of the ligands (0.7–1 nm). The appearance of a well

Experimental and simulation-based investigation of He, Ne and Ar irradiation of polymers for ion microscopy

• Lukasz Rzeznik,
• Yves Fleming,
• Tom Wirtz and
• Patrick Philipp

Beilstein J. Nanotechnol. 2016, 7, 1113–1128, doi:10.3762/bjnano.7.104

• ions and the samples. Numerical simulations are one tool which can provide important information about particle–surface interactions, both for inorganic [12][13][14][15] and organic samples [16][17][18][19]. For the analysis of organic matter, information on preferential sputtering and the modification

• Ne+ bombardment will be compared to Ar+ bombardment for several polymers and several impact energies. The objective is to identify possible artefacts related to the sputter process and to control them. The study relies on experimental work and numerical simulations making use of the SD_TRIM_SP [25

• and why the behaviour of polymers under rare gas irradiation differs from inorganic materials, numerical simulations have been carried out to study the diffusion behaviour of these species in polymers, the degradation of polymers under rare gas ion bombardment as a function of fluence and the

The influence of phthalocyanine aggregation in complexes with CdSe/ZnS quantum dots on the photophysical properties of the complexes

• Irina V. Martynenko,
• Anna O. Orlova,
• Vladimir G. Maslov,
• Anatoly V. Fedorov,
• Kevin Berwick and
• Alexander V. Baranov

Beilstein J. Nanotechnol. 2016, 7, 1018–1027, doi:10.3762/bjnano.7.94

• transfer efficiency in the case of PcS4 demonstrates the opposite dependence on n when compared to that for the original mixture. Numerical simulations show that the experimental dependencies of QY of phthalocyanine PL on n are well fitted with a curve calculated using Equation 11 from the model with α

A terahertz-vibration to terahertz-radiation converter based on gold nanoobjects: a feasibility study

• Kamil Moldosanov and
• Andrei Postnikov

Beilstein J. Nanotechnol. 2016, 7, 983–989, doi:10.3762/bjnano.7.90

• separated (at ca. 2.4 and ca. 4.2 THz, respectively), as it was discussed by Bayle et al. [3] (see Figure 2). Credible numerical simulations comply quite well, even quantitatively, with such a neat separation of the vibration spectrum of gold into two peaks, in what concerns nanoparticles [9] as well as the

An adapted Coffey model for studying susceptibility losses in interacting magnetic nanoparticles

• Mihaela Osaci and
• Matteo Cacciola

Beilstein J. Nanotechnol. 2015, 6, 2173–2182, doi:10.3762/bjnano.6.223

• Numerical simulations We considered a system with spherical nanoparticles made of uncoated magnetite, with the following characteristics: density ρ = 5180 kg/m3 [3]; saturation magnetization Ms = 4.46·105 A/m [3]; uniaxial magnetic anisotropy with anisotropy constant Keff = 25·103 J/m3 [3]; random

Thermoelectricity in molecular junctions with harmonic and anharmonic modes

• Bijay Kumar Agarwalla,
• Jian-Hua Jiang and
• Dvira Segal

Beilstein J. Nanotechnol. 2015, 6, 2129–2139, doi:10.3762/bjnano.6.218

• temperature T =300 K for the harmonic and anharmonic-mode junctions. In the numerical simulations below the phononic contribution to the thermal conductance is ignored, assuming it to be small compared to its electronic counterpart. A quantitative analysis of the contribution of the phononic thermal

• nontrivial order) in the electron phonon coupling g. This is evident from the structure of the rate constants in Equation 10, as electron transfer is facilitated by the absorption/emission of a single quantum ω0. In numerical simulations we typically employed g = 0.01 eV and ω0 = 0.02 eV. This value for g

Magnetic reversal dynamics of a quantum system on a picosecond timescale

• Nikolay V. Klenov,
• Alexey V. Kuznetsov,
• Igor I. Soloviev,
• Sergey V. Bakurskiy and
• Olga V. Tikhonova

Beilstein J. Nanotechnol. 2015, 6, 1946–1956, doi:10.3762/bjnano.6.199

• pulse duration can lead to demagnetization in the system, which is confirmed by the results of the numerical simulations. It is important to pay attention to this profound analogy between the quantum and the classical results in order to separate the macroscopic and quantum modes in mesoscopic systems

Attenuation, dispersion and nonlinearity effects in graphene-based waveguides

• Almir Wirth Lima Jr.,
• João Cesar Moura Mota and
• Antonio Sergio Bezerra Sombra

Beilstein J. Nanotechnol. 2015, 6, 1221–1228, doi:10.3762/bjnano.6.125

• supported in graphene when and , respectively. By numerical simulations it was proved that energy is absorbed or dissipated when . However, if we consider a fixed graphene chemical potential, the temperature increase causes a finite damping, which is smaller for TM vs TE modes. This is because the real

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

• different parameters we have used numerical simulations. For this we consider that bimodal AFM is characterized by the simultaneous excitation of two cantilever resonant frequencies, usually the lowest flexural eigenmodes [42]. The total driving force is expressed as Then, the cantilever–tip ensemble will

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

• –Jarvis–Katan formalism in numerical simulations (see Experimental section). The results of the simulations are shown in Figure 3, in which simulated Fts curves (Figure 3b and Figure 3d) are compared with the experimental curves (Figure 3a and Figure 3c). Forces such as those in Equation 10 and Equation

• this case or, equivalently, that the distances of formation and rupture of the capillary bridge are similar. In Figure 4 normalized force curves reconstructed on CaF2 crystals in dry conditions (Figure 4a), are compared with the results of numerical simulations (Figure 4b). Both panels include Ediss

Production, detection, storage and release of spin currents

• Michele Cini

Beilstein J. Nanotechnol. 2015, 6, 736–743, doi:10.3762/bjnano.6.75

• –orbit interaction in the ring. Results: Such a magnetic current is even under time reversal and produces an electric field instead of the usual magnetic field. Numerical simulations show that one can use magnetizable bodies as storage units to concentrate and save the magnetization in much the same way

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

• simulations. Finally, the accuracy of dForce has been tested against numerical simulations performed during the last 18 years. Keywords: bimodal AFM; dynamic AFM; nanomechanics; numerical simulations; tapping mode AFM; Introduction Numerical simulations have played a pivotal role to advance the

• dissipated in the sample [8][9][10]. Numerical simulations have provided critical insight to understand the subtle nonlinear dynamics aspects present in AM-AFM, such as the existence of multiple interaction regimes [11][12][13] or the presence of chaotic tip motion [14]. Similarly, simulations have linked

• excitation methods have been analyzed by simulations [21][22][23]. The tip–surface force controls the cantilever motion, however, the force itself is not an observable. Numerical simulations have been used to derive parametric approximations [24], scaling laws [25] and insights about the role of different

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

• between observables and sample properties. Furthermore, the extraction of sample properties becomes especially challenging when studying viscoelastic materials. Despite the obstacles, analytical and numerical simulations have been performed as an attempt to estimate quantities such the sample loss tangent

• developed [21]. Methods Numerical simulations of the cantilever dynamics were performed for most of the cases according to single-eigenmode tapping mode AFM, unless otherwise indicated. To model the dynamics of the cantilever we included the contribution of the first three flexural modes of the cantilever

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

• cycle in z with vx = v0 cos(ωxt) and , which yields If we just consider one oscillation cycle in our numerical simulations, we start at the upper turning point of the normal oscillation but the lateral excitations set in at the lower turning point. Thus the dissipation values will be just half of the

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

• , [Amin,e; Amax,e], where Amax = max A(t) = max z(t). As numerical simulations have shown, the error function does not have a well-defined global minimum and it is highly sensitive to reconstruction errors. An alternative approach is to minimize a mean square error function in real space which in most

• unknown parameters using the measured difference spectrum Ve − Vf. If the exact expression for F is unknown, ImAFM provides enough information to reconstruct it in a generic form, e.g., as power series (Equation 5). As numerical simulations have shown, a more realistic model gives better calibration with

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

• viscoelastic surfaces. Methods The numerical simulations of the cantilever dynamics were carried out including three eigenmodes of the AFM cantilever as in previous studies [24][42]. Active eigenmodes, as indicated throughout the paper, were driven at their natural frequency. The surface was modeled in most

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

• PTFE pipe thread seal tape (nominal thickness ca. 0.1 mm) stretched onto the back of single-sided scotch tape, which was adhered sticky side down onto a metal substrate. This type of polymer sample was chosen in order to obtain high contrast in the phase signals. Computational For the numerical

• simulations five eigenmodes of the AFM cantilever were modeled by using individual equations of motion for each, coupled through the tip–sample interaction forces as in previous studies [8][20]. Driven eigenmodes were excited through a sinusoidal tip force of constant amplitude, and frequency equal to the

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

• experiments on Nafion® proton exchange membranes and numerical simulations illustrating the trade-offs between the optimization of compositional contrast and the modulation of tip indentation depth in bimodal atomic force microscopy (AFM). We focus on the original bimodal AFM method, which uses amplitude

• container. During the experiments reported in this paper, the air in the AFM chamber was monitored to be at 23 °C and 17% relative humidity. Computational For the numerical simulations the first three eigenmodes of the AFM cantilever were modeled by using individual equations of motion for each, coupled

• cases was 17 nm, with an amplitude setpoint of 80% for attractive regime imaging and 50% for repulsive regime imaging. Simulations of maximum indentation and peak force (see section Methods below for details on the numerical simulations of the cantilever dynamics as well as the tip–sample force model

Classical molecular dynamics investigations of biphenyl-based carbon nanomembranes

• Andreas Mrugalla and
• Jürgen Schnack

Beilstein J. Nanotechnol. 2014, 5, 865–871, doi:10.3762/bjnano.5.98

• by up to three Ångstroms from their equilibrium position in a phenyl. For larger displacements the respective bonds can be considered as broken. As will be discussed later, our numerical simulations strongly suggest that initial states with broken bonds are the only ones that yield two-dimensionally

The optimal shape of elastomer mushroom-like fibers for high and robust adhesion

• Burak Aksak,
• Korhan Sahin and
• Metin Sitti

Beilstein J. Nanotechnol. 2014, 5, 630–638, doi:10.3762/bjnano.5.74

• . Description of the cohesive zone model and numerical simulations are included in sections “Cohesive zone model” and “Numerical simulations”, respectively. After that, the results of the finite element simulations are presented, and in the subsequent section the detachment behavior of individual fibers, the

• . Numerical simulations Simulations are performed for a mushroom-like fiber illustrated in Figure 2 by using the analysis software COMSOL MultiPhysics 4.3 FE. It is assumed that the fiber is in full friction contact with a rigid smooth surface, which is in line with our observations during experiments with

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

• Tabor coefficient, allowing one to estimate if a contact is closer to DMT or to JKR theory. He actually recognized that DMT and JKR describe the opposite limits of long- and short-range forces, respectively. This had not been known before but was soon confirmed in numerical simulations by Muller

Challenges and complexities of multifrequency atomic force microscopy in liquid environments

• Santiago D. Solares

Beilstein J. Nanotechnol. 2014, 5, 298–307, doi:10.3762/bjnano.5.33

• questions that require further attention within multifrequency AFM. Methods For the numerical simulations three eigenmodes of the AFM cantilever were modeled using individual equations of motion for each, coupled through the tip–sample interaction forces as in previous studies [9][38]. Driven eigenmodes

Charge and spin transport in mesoscopic superconductors

• M. J. Wolf,
• F. Hübler,
• S. Kolenda and
• D. Beckmann

Beilstein J. Nanotechnol. 2014, 5, 180–185, doi:10.3762/bjnano.5.18

• nonlocal conductance according to Equation 2 in Figure 2a. For large bias, the experimental data (both gnl and ) deviate downward from the fits. Full numerical simulations that include cooling, with the characteristic inelastic scattering time τE as the only remaining fit parameter, are shown as solid

Peak forces and lateral resolution in amplitude modulation force microscopy in liquid

• Horacio V. Guzman and
• Ricardo Garcia

Beilstein J. Nanotechnol. 2013, 4, 852–859, doi:10.3762/bjnano.4.96

• Horacio V. Guzman Ricardo Garcia Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juan Ines de la Cruz 3, 28049 Madrid, Spain 10.3762/bjnano.4.96 Abstract The peak forces exerted on soft and rigid samples by a force microscope have been modeled by performing numerical simulations of the

• tip motion in liquid. The forces are obtained by using two contact mechanics models, Hertz and Tatara. We present a comparison between the numerical simulations and three analytical models for a wide variety of probe and operational parameters. In general, the forces derived from analytical

• , the use of force inversion methods has not been generalized in AM-AFM because the accuracy of some of the above methods is still under study. On the other hand, numerical simulations have been used to determine the maximum repulsive interaction forces, which are referred to as peak forces hereafter

Size-dependent characteristics of electrostatically actuated fluid-conveying carbon nanotubes based on modified couple stress theory

• Mir Masoud Seyyed Fakhrabadi,
• Abbas Rastgoo and
• Mohammad Taghi Ahmadian

Beilstein J. Nanotechnol. 2013, 4, 771–780, doi:10.3762/bjnano.4.88

• because of the higher costs of experimentation and less elaborated fabrication technologies for nanotechnology. Thus, numerical simulations that include discrete and continuum modeling techniques are conducted more often. In spite of the higher accuracy of discrete modeling approaches such as molecular