On the frequency dependence of viscoelastic material characterization with intermittent-contact dynamic atomic force microscopy: avoiding mischaracterization across large frequency ranges

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

Beilstein J. Nanotechnol. 2020, 11, 1409–1418, doi:10.3762/bjnano.11.125

• methods have found niches of application and have provided physical insight into a wide variety of materials. In keeping with the above trajectory in the development of new AFM methods for viscoelastic materials, in recent years we have focused on the application of linear viscoelasticity within quasi

• cantilevers used to properly characterize it. However, one should be surprised to see hardly any hysteresis in the force trajectory of material 2 despite its obvious viscoelastic nature depicted in Figure 2. One must therefore consider whether the cantilever stiffness used is appropriate, since the force

• the cantilever stiffness over the sample stiffness. Figure 5b compares the force trajectory during impact for both values of the force constant, and indeed, we observe significantly greater indentation and repulsive forces for the stiffer cantilever. Furthermore, the force trajectory now shows an

Thermophoretic tweezers for single nanoparticle manipulation

• Jošt Stergar and
• Natan Osterman

Beilstein J. Nanotechnol. 2020, 11, 1126–1133, doi:10.3762/bjnano.11.97

• trapping potential was characterized using the standard procedure for optical tweezers calibration [33]: from the recorded trajectory of the particle positions, the probability density ρ(x) distribution was obtained. Although the discussed process is a non-equilibrium process one can still define the

• a delta-correlated stationary Gaussian process with zero-mean, satisfying ⟨R(t)R(t’)⟩ = δ(t – t’). The equation was solved with a finite difference method with a time step of 100 µs. The particle trajectory for a duration of 1000 s was simulated for each combination of parameters. Figure 3 presents

• for a single 200 nm particle. (a) 2D histogram of particle positions. (b) Cross section of the effective potential in x- and y-directions. Manipulation of a 200 nm nanoparticle in water. (a) The trajectory of the particle. (b) Time dependence of x- and y-position of the particle during 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

• dynamic current measurements, this manuscript discusses three different cases: (i) a noncontact dynamic current measurement where the cantilever follows an ideal sinusoidal trajectory, (ii) a similar case, but considering a more realistic trajectory where the tip oscillation is perturbed by the presence

• trajectory Consider an AFM tip oscillating over a surface with a perfect cosine trajectory, without impacting the surface (Figure 1). In this case the distance between the AFM tip and the surface can be written as where d is the instantaneous tip–sample distance, h is the equilibrium tip position, A is the

• analyse the result, we take the Fourier transform of the series in Equation 7: We will return to this expression in order to analyse and visualize it in the Results section. Case 2: Dynamic noncontact current measurement with realistic tip trajectory A real AFM tip trajectory exhibits perturbations due to

Understanding nanoparticle flow with a new in vitro experimental and computational approach using hydrogel channels

• Armel Boutchuen,
• Dell Zimmerman,
• Abdollah Arabshahi,
• John Melnyczuk and
• Soubantika Palchoudhury

Beilstein J. Nanotechnol. 2020, 11, 296–309, doi:10.3762/bjnano.11.22

• related to flow of NPs such as the quantity of NPs lost during transport and flow trajectory greatly affect the clinical efficiency of NP drug delivery systems. Currently, there is little knowledge of the physical mechanisms dominating NP flow inside the human body due to the limitations of available

• vivo methods for a more efficient and reliable evaluation of NP drugs [12]. However, many variables such as the size, surface chemistry, and interaction of the NPs with different biological compounds within the body influence the trajectory of NPs in vivo [13][14][15]. This makes it challenging to

• trajectory of NPs. In the case of soft hydrogel-based flow channels constructed to mimic vascular networks, the larger sized NPs moved slower than the smaller NPs, similar to trends seen in macroscale objects. This phenomenon could be explained in terms of two factors, a dominance of Brownian forces over

Long-term entrapment and temperature-controlled-release of SF₆ gas in metal–organic frameworks (MOFs)

• Hana Bunzen,
• Andreas Kalytta-Mewes,
• Leo van Wüllen and
• Dirk Volkmer

Beilstein J. Nanotechnol. 2019, 10, 1851–1859, doi:10.3762/bjnano.10.180

• extracted from the previous force field scan trajectory and all atomic positions were allowed to relax during subsequent optimization steps, except for the position of the sulfur atom of SF6, which was fixed at the corresponding c/N coordinate of the transition path. The PW-DFT+D calculations were performed

Choosing a substrate for the ion irradiation of two-dimensional materials

• Egor A. Kolesov

Beilstein J. Nanotechnol. 2019, 10, 531–539, doi:10.3762/bjnano.10.54

• assumed in [16]. The overall most pronounced effect is naturally observed for the copper substrate, with the results for Al2O3 being remarkably close. While inelastic collisions with the electronic sea naturally do not change the ion trajectory, the maxima in Figure 2 correspond to the strongest relative

Intuitive human interface to a scanning tunnelling microscope: observation of parity oscillations for a single atomic chain

• Sumit Tewari,
• Jacob Bakermans,
• Christian Wagner,
• Federica Galli and
• Jan M. van Ruitenbeek

Beilstein J. Nanotechnol. 2019, 10, 337–348, doi:10.3762/bjnano.10.33

• to the motion control system that provides a continuous visual feedback to the operator during atomic manipulation. This allows the operator to become a part of the experiment and to make any adaptable tip trajectory that could be useful for atomic manipulation in three dimensions. The strength of

• ]. Therefore, the knowledge about the structure of the junction at the atomic scale is critical to the understanding of these transport measurements. The system that we have developed addresses this problem. We have added a 3D motion control system to our STM that helps in making any required tip trajectory

• then choose to make a desired trajectory for better control of the manipulation process. This is especially important in the case of 3D manipulation of single molecules and atomic chains, as there are no predefined accurate trajectories [5][6] that one can set to do those manipulations. Therefore an

Investigation of CVD graphene as-grown on Cu foil using simultaneous scanning tunneling/atomic force microscopy

• Majid Fazeli Jadidi,
• Umut Kamber,
• Oğuzhan Gürlü and
• H. Özgür Özer

Beilstein J. Nanotechnol. 2018, 9, 2953–2959, doi:10.3762/bjnano.9.274

• images of a graphene surface are shown in Figure 1. In this experiment, the forward scan was performed in constant current mode and the backward scan in constant height mode, for a proper extraction of the tip–sample force, which might have been potentially affected by the varying tip trajectory. STM

• ) and constant-height (CH) scans. The force corrugation contrast between carbon and hollow sites is found to be about 0.1 nN for both CC and CH modes. Thus, as far as the force is concerned the tip trajectory in CC mode does not have a considerable influence on the measurement of the oscillation

Time-resolved universal temperature measurements using NaYF₄:Er³⁺,Yb³⁺ upconverting nanoparticles in an electrospray jet

• Kristina Shrestha,
• Arwa A. Alaulamie,
• Ali Rafiei Miandashti and
• Hugh H. Richardson

Beilstein J. Nanotechnol. 2018, 9, 2916–2924, doi:10.3762/bjnano.9.270

• Taylor cone angle. The sampling time reduces to 2 μs at the tip. (B) A plot of temperature calculated along the trajectory of a Taylor cone at room temperature (296 K) and at elevated temperature (306 K). The sampling time at a given distance is indicated in the figure. A schematic illustration for a

Disorder in H⁺-irradiated HOPG: effect of impinging energy and dose on Raman D-band splitting and surface topography

• Lisandro Venosta,
• Noelia Bajales,
• Sergio Suárez and
• Paula G. Bercoff

Beilstein J. Nanotechnol. 2018, 9, 2708–2717, doi:10.3762/bjnano.9.253

• domain size by considering the intensity ratio ID/IG. Likewise, Ferrari [9] proposed that the evolution of Raman spectra can be fitted by a phenomenological model in agreement with the amorphization trajectory for graphitic nanocrystallites. The authors pointed out that the ID/IG intensity ratio depends

The inhibition effect of water on the purification of natural gas with nanoporous graphene membranes

• Krzysztof Nieszporek,
• Tomasz Pańczyk and
• Jolanta Nieszporek

Beilstein J. Nanotechnol. 2018, 9, 1906–1916, doi:10.3762/bjnano.9.182

• illustration of the clustering of water molecules in the NN nanopore can be seen in Figure 10. The picture has been extracted from the simulation trajectory at a time of 5 ns. In Figure 7 (right panel, red curve) an attentive reader can see a decrease of the number of water molecules in the permeate area at a

• . The extracted frame from the simulation trajectory of the separation of CH4 + N2 + 200 H2O with an NN nanopore at a time of 5 ns. Green, blue and red molecules are methane, nitrogen and water, respectively. The temperature influence on the number of molecules passing across the pore as a function of

• ). The right plot presents the time dependence of the distance between the center of nanopore and that plane. Data were determined from the simulation trajectory of CH4 + N2 + 200 H2O at 300 K. Time evolution of the second kind of deviation. Data were determined from the simulation trajectory of CH4 + N2

Tunable fractional Fourier transform implementation of electronic wave functions in atomically thin materials

• Daniela Dragoman

Beilstein J. Nanotechnol. 2018, 9, 1828–1833, doi:10.3762/bjnano.9.174

• coordinate x and the tangent θ to the ray/quantum trajectory at a y = const. plane and the same parameters (indexed by 0) at the y = 0 plane [15]: In Equation 5, valid when or , one has in optics and in the case of Schrödinger electrons. Whether the results above regarding Schrödinger electrons are not

• of the spinorial wave function satisfy the equation which is similar to Equation 2 if , , . As a result, the FrFT of order α is achieved after a propagation distance in graphene equal to and the trajectory of charge carriers in graphene is also periodic and described by Equation 5, with . Again, the

• implements a FrFT for negative UG potentials, while that in Figure 1b implements it for positive UG values. Figure 1a and Figure 1b depict also the trajectory of a ballistic electron. From Equation 4 and Equation 8 it follows that the last configuration implements a FrFT with a given α in a shorter distance

Atomistic modeling of tribological properties of Pd and Al nanoparticles on a graphene surface

• Alexei Khomenko,
• Miroslav Zakharov,
• Denis Boyko and
• Bo N. J. Persson

Beilstein J. Nanotechnol. 2018, 9, 1239–1246, doi:10.3762/bjnano.9.115

• one of a large number of available thermostats is used. Velocity rescaling by a constant factor, which corresponds to the desired temperature, is the simplest way to maintain the necessary temperature. Here we use the Berendsen thermostat [16][17] that does not give the trajectory of the true

Thermoelectric current in topological insulator nanowires with impurities

• Sigurdur I. Erlingsson,
• Jens H. Bardarson and
• Andrei Manolescu

Beilstein J. Nanotechnol. 2018, 9, 1156–1161, doi:10.3762/bjnano.9.107

• for quadratic dispersion (Schrödinger) where the Lorentz force always bends the electron trajectory towards the line of vanishing radial component of the magnetic field [27][28][29][30]. In fact, this is a classical effect known in the two-dimensional electron gas in inhomogeneous magnetic fields with

Imaging of viscoelastic soft matter with small indentation using higher eigenmodes in single-eigenmode amplitude-modulation atomic force microscopy

• Miead Nikfarjam,
• Enrique A. López-Guerra,
• Santiago D. Solares and
• Babak Eslami

Beilstein J. Nanotechnol. 2018, 9, 1116–1122, doi:10.3762/bjnano.9.103

• 1 (Figure S1). The contact mechanics described by Equation 4 are strictly only valid for the approach portion of the indenter trajectory. A generalized approach has been derived by Ting, which is applicable for any arbitrary (a priori) known loading history [21]. In our simulations, where a priori

• eigenmode, and bimodal AFM using the first two eigenmodes. In all cases, the product(s) kiAi of the active eigenmode(s) was/were kept constant. Figure 2a presents the peak force observed during the cantilever trajectory as a function of the setpoint ratio of the modulated amplitude. Figure 2b presents the

Dynamics and fragmentation mechanism of (C₅H₄CH₃)Pt(CH₃)₃ on SiO₂ surfaces

• Kaliappan Muthukumar,
• Harald O. Jeschke and
• Roser Valentí

Beilstein J. Nanotechnol. 2018, 9, 711–720, doi:10.3762/bjnano.9.66

• originally bonded to Pt, fragments and bonds to the adjacent vacant site, as observed in the 3 × 3 × 4 cell (see Figure 2d and Figure 3e). These DFT relaxed structures (as shown in Figure 3b–e) are considered as starting point for molecular dynamics simulations. The trajectory of the MD simulations for the

• four considered cases are shown in Figure 4. The analysis of the trajectory indicates that on the fully hydroxylated surfaces (Figure 4a) the molecule exhibits significant changes in orientation and a drift similar as we found for carbonyl precursors [11]. The Pt–Cp ring and Pt–methyl bonds fluctuate

• with a maximum of 5% and 1%, respectively. Apart from this, in the simulation window, we do not observe any further indications of the dissociation of the precursor molecules. The trajectory of MD simulations and arising configurations of (C5H4CH3)Pt(CH3)3 on the (25% and 50%) partially dehydroxylated

The nanofluidic confinement apparatus: studying confinement-dependent nanoparticle behavior and diffusion

• Stefan Fringes,
• Felix Holzner and
• Armin W. Knoll

Beilstein J. Nanotechnol. 2018, 9, 301–310, doi:10.3762/bjnano.9.30

• mean squared displacement (MSD) in one of the orthogonal directions x or y. For the x-direction and a time interval Δt, the MSD is given by where signifies the ensemble average, N is the number of observed positions per trajectory, Kα is a generalized diffusion coefficient and α is the anomalous

Material discrimination and mixture ratio estimation in nanocomposites via harmonic atomic force microscopy

• Weijie Zhang,
• Yuhang Chen,
• Xicheng Xia and
• Jiaru Chu

Beilstein J. Nanotechnol. 2017, 8, 2771–2780, doi:10.3762/bjnano.8.276

• are neglected. R is the tip radius and E* is the reduced modulus where v Poisson’s ratio. Combining Equation 2 and Equation 3 and utilizing numerical methods such as Runge–Kutta algorithms, the real-time oscillation trajectory of the tip can be achieved. The above contact model is based on the main

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

• sinusoidal trajectory. From the rheological viewpoint, the characterization of viscoelastic materials has been classically performed by applying a well-defined input excitation (either stress or sample strain) to elicit a response, which is then measured. The measured output response and the well-defined

• classical rheology, we regard tapping-mode AFM as a non-standard excitation of a viscoelastic sample, and exploit the fact that the near sinusoidal nature of the tip deflection in this technique implies that the sample necessarily experiences a portion of that sinusoidal trajectory during the contact period

• tip trajectory for an AFM cantilever interacting with a viscoelastic surface in tapping-mode AFM (simulation details are provided in the figure caption). The instantaneous tip–sample distance, taking as reference the undeformed sample surface, is approximately given by: where Zeq refers to the average

Bi-layer sandwich film for antibacterial catheters

• Gerhard Franz,
• Florian Schamberger,
• Hamideh Heidari Zare,
• Sara Felicitas Bröskamp and
• Dieter Jocham

Beilstein J. Nanotechnol. 2017, 8, 1982–2001, doi:10.3762/bjnano.8.199

• layer, which had been coated by PPX-N (1650 and 2240 nm). According to the equivalent circuit in Figure 11, the intersection of the graph with the real axis close to the origin is related to the serial ohmic resistance RΩ of the NaOH solution. The semi-circle trajectory, which approaches the shape of a

Optical techniques for cervical neoplasia detection

• Tatiana Novikova

Beilstein J. Nanotechnol. 2017, 8, 1844–1862, doi:10.3762/bjnano.8.186

• –Chipman decomposition implies a sequential order of elementary polarimetric properties along the trajectory of the probing beam, whereas these polarimetric properties can be mixed within the volume of tissue. Nevertheless, these effective values of depolarization and retardance are found to be the

High-speed dynamic-mode atomic force microscopy imaging of polymers: an adaptive multiloop-mode approach

• Juan Ren and
• Qingze Zou

Beilstein J. Nanotechnol. 2017, 8, 1563–1570, doi:10.3762/bjnano.8.158

• +feedforward) applied to the z-piezo actuator (i.e., Uff+fb,k(jω) = Uff,k(jω) + Ufb,k(jω), see Figure 9), and the z-piezo displacement measured on the k-th scan line, respectively, and Hffd,k+1(·) denotes the desired trajectory that the z-piezo needs to track at the (k+1)-th scanline. Note that the ratio 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

• , represented by the force field Fts, between the cantilever tip and the surface [1]. Thus, the time dependent trajectory a(t) of the cantilever tip, which can be expressed in the harmonic limit by a(t) = A1cos(2πft), is transformed into a Fourier series with harmonic oscillations of amplitudes An and

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

• follows a different trajectory than during the approach (4–4′ in Figure 5b) giving rise to force–displacement curve hysteresis. The two discontinuities in the force values are called jump-to-contact in the approach curve and jump-off-contact in the withdrawal curve. It is important to mention that this

First examples of organosilica-based ionogels: synthesis and electrochemical behavior

• Andreas Taubert,
• Ruben Löbbicke,
• Barbara Kirchner and
• Fabrice Leroux

Beilstein J. Nanotechnol. 2017, 8, 736–751, doi:10.3762/bjnano.8.77

• thermostats (parameters as in [41]) for 5 ps. After this the simulation was done in an NVT ensemble to provide 2.5 ps production trajectory at 450 K which was analyzed with the software TRAVIS [43]. A forthcoming publication will provide more details and longer simulation times. Figure 1 shows the simulation

• increases the intramolecular bond to approximately 150 pm either a cation SO3 group or one of the tosylate anions is close. A very large O–H distance of a former intramolecular O–H group can correlate with both, a short O–H anion or cation distance. Moreover, inspection of the trajectory clearly shows that