Bio-inspired micro-to-nanoporous polymers with tunable stiffness

• Julia Syurik,
• Ruth Schwaiger,
• Prerna Sudera,
• Stephan Weyand,
• Siegbert Johnsen,
• Gabriele Wiegand and
• Hendrik Hölscher

Beilstein J. Nanotechnol. 2017, 8, 906–914, doi:10.3762/bjnano.8.92

• overall damping capability of the material. All tests were conducted at room temperature (25.5 °C) under ambient conditions. The measurements were performed at 20 different positions arranged in an array of 5 by 4 (see below in Figure 2b). Results and Discussion Porous PMMA films were produced via a

• thickness. The damping capability at room temperature is dominated rather by the material than the structure. Similar findings were reported for nanoporous PMMA with a relative density of 40% and pore sizes of approx. 200 nm and approx. 300 nm [21]. The mechanical properties of a foam usually depend on the

• foam, as can be seen in Figure 5a. This results in a loss factor that does not depend on the pore size, but rather reflects the damping capability of PMMA (Figure 5b). The decreasing storage modulus might also be caused by a partial damage of PMMA material and the shortening of the polymeric chains. In

Optimizing qPlus sensor assemblies for simultaneous scanning tunneling and noncontact atomic force microscopy operation based on finite element method analysis

• Omur E. Dagdeviren and
• Udo D. Schwarz

Beilstein J. Nanotechnol. 2017, 8, 657–666, doi:10.3762/bjnano.8.70

• values used for Young’s modulus E, the density ρ, Poisson’s ratio υ, and the damping coefficient η for all materials considered in the modeling, with values for quartz, epoxy glue, and Macor chosen as in [26] while the ones for gold and tungsten were taken from the material library of the simulation

• software [27]. Also note that (i) due to the comparatively low internal damping occurring inside Macor, gold, and tungsten, we do not assign a damping coefficient to any of these materials to speed up the calculations, and that (ii) the sensor is oscillating in vacuum; for experimentation in air, we would

• have to expect considerable additional viscous damping [28]. The model setup used for the FEM calculations is illustrated in Figure 1a. As in the earlier model of [26], boundary conditions for determining spring constant, quality factor, resonance frequency, and perturbation of the ideal vertical

Multimodal cantilevers with novel piezoelectric layer topology for sensitivity enhancement

• Steven Ian Moore,
• Michael G. Ruppert and
• Yuen Kuan Yong

Beilstein J. Nanotechnol. 2017, 8, 358–371, doi:10.3762/bjnano.8.38

• was shown that these higher modes can be more sensitive to material properties such as elastic modulus and damping coefficients [17][18][19]. Additionally, stiff cantilevers have proven to provide high resolution imaging in ambient and liquid environments using quartz resonators [20][21]. Traditional

Optical and photocatalytic properties of TiO₂ nanoplumes

• Viviana Scuderi,
• Massimo Zimbone,
• Maria Miritello,
• Giuseppe Nicotra,
• Giuliana Impellizzeri and
• Vittorio Privitera

Beilstein J. Nanotechnol. 2017, 8, 190–195, doi:10.3762/bjnano.8.20

• reflectance spectrum of the titanium layer before the chemical etching. We assumed that the functional form for the dielectric constant of the metallic film is given by the “Drude free carrier” expression [26]: where ω, ωP, γ and ε∞ are, respectively, the light frequency, the plasma frequency, the damping

• using a Forouhi–Bloomer (FB) functional form for amorphous samples [27][28][29]: where and Θ(ω − ωg) is a step function, ωg is the energy gap of the amorphous material, n∞, A, ω0, Γ are the “low-frequency” refractive index, the amplitude, the position, and the damping constant of the FB oscillator

Tunable plasmons in regular planar arrays of graphene nanoribbons with armchair and zigzag-shaped edges

• Cristian Vacacela Gomez,
• Michele Pisarra,
• Mario Gravina and
• Antonello Sindona

Beilstein J. Nanotechnol. 2017, 8, 172–182, doi:10.3762/bjnano.8.18

• in energy, with the zeroes of the real permittivity being hidden by the Landau damping mechanism, associated to single-particle excitation processes [25][46][47][48]. In 11AGNR the same modes strongly interfere and largely dominate with respect to single-particle excitations. A similar interplay was

• ). The energy region ω ≤ 1 eV is explored at a fixed incident momentum q = 0.011 Å−1 parallel to ΓX (Figure 2g), with a negative doping level ΔEF of −0.1 eV. The black arrows mark the positions where the real permittivity has a zero value (a–c) or a minimum (d), which reflects a Landau damping mechanism

Electron energy relaxation under terahertz excitation in (Cd_1−xZn_x)₃As₂ Dirac semimetals

• Alexandra V. Galeeva,
• Ivan V. Krylov,
• Konstantin A. Drozdov,
• Anatoly F. Knjazev,
• Alexey V. Kochura,
• Alexander P. Kuzmenko,
• Vasily S. Zakhvalinskii,
• Sergey N. Danilov,
• Ludmila I. Ryabova and
• Dmitry R. Khokhlov

Beilstein J. Nanotechnol. 2017, 8, 167–171, doi:10.3762/bjnano.8.17

• that such behavior is attributed to a strong damping of the interelectron interaction in the Dirac semimetal phase compared to the trivial semiconductor, which may be due to the formation of surface electron states with a spin texture in Dirac semimetals. Keywords: Dirac semimetal; photo

Dynamic of cold-atom tips in anharmonic potentials

• Tobias Menold,
• Peter Federsel,
• Carola Rogulj,
• Hendrik Hölscher,
• József Fortágh and
• Andreas Günther

Beilstein J. Nanotechnol. 2016, 7, 1543–1555, doi:10.3762/bjnano.7.148

• distribution, the dephasing will thus lead to a broadening of the distribution function, a decrease of the peak density and a damping of the center-of-mass oscillation. Finally, the atoms will be spread over the whole oscillation region, with no center-of-mass oscillation remaining. The density distribution

• are identical as before, while the anharmonic trap has been extended in the transversal direction by a harmonic confinement with frequency ωy/z = 2π × 500 Hz. For comparison, Figure 3 includes the result for noninteracting particles, showing a reduced damping. Following Equation 12, the damping time

• harmonic results (black line) are shown. The oscillation of the tip and the damping due to dephasing are clearly visible in the anharmonic data. As expected, the damping is strongest for the data including particle collisions. Experiments Our experimental setup is based on a cold-atom apparatus, the same

Localized surface plasmons in structures with linear Au nanoantennas on a SiO₂/Si surface

• Ilya A. Milekhin,
• Sergei A. Kuznetsov,
• Ekaterina E. Rodyakina,
• Alexander G. Milekhin,
• Alexander V. Latyshev and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2016, 7, 1519–1526, doi:10.3762/bjnano.7.145

• frequency, and νp ≈ 72500 cm−1 and νc ≈ 216 cm−1 are the linear plasma frequency and the damping frequency, respectively [39]. In the simulations, the width b and the height t of the nanoantennas were assumed to be 50 nm with an the axial gap of a = 100 nm (see Figure 5a) as it was imposed by our

Electric field induced structural colour tuning of a silver/titanium dioxide nanoparticle one-dimensional photonic crystal

• Eduardo Aluicio-Sarduy,
• Simone Callegari,
• Diana Gisell Figueroa del Valle,
• Andrea Desii,
• Ilka Kriegel and
• Francesco Scotognella

Beilstein J. Nanotechnol. 2016, 7, 1404–1410, doi:10.3762/bjnano.7.131

• initial carrier density (N), such that NE > N. The Drude model can be used to predict the behaviour of the plasmonic response in the photonic crystal [19]. The frequency-dependent complex dielectric function of silver can be written as where and with Γ representing the free carrier damping [20]. The

• surrounding, however, also largely influences the position of the plasmon resonance [29]. In addition, doping occurs only in a thin layer at the nanoparticle surface. These two effects also ultimately impact on the carrier damping, which in our estimation was kept constant. Studies on the accumulation of

• charges in an ITO film by applying a constant voltage demonstrated that besides an increase in carrier density, other Drude parameters such as the damping constant and the high frequency dielectric constant are altered through the introduction of additional carriers [30]. Thus, a deeper study of the

Functional diversity of resilin in Arthropoda

• Jan Michels,
• Esther Appel and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2016, 7, 1241–1259, doi:10.3762/bjnano.7.115

• resilin due to its low stiffness, high resilience, large and reversible extensibility, long fatigue time and ability of elastic energy storage and damping. One of these flight system elements is a sausage-like swollen thoracic dragonfly tendon, which consists of virtually pure resilin and connects the

• stiffness and to improve the damping properties of the vein as well as to delay Brazier ovalisation and to enhance the load-bearing capacity under large deformations [79][88]. By artificially stiffening single flexible, resilin-bearing vein joints in bumblebee wings through the application of micro-splints

• the resistance of the teeth to mechanical damages. Additional structures with large resilin proportions, located in the central and proximal parts of the gnathobases, are assumed to have a damping function that makes the whole gnathobases resilient and further reduces the risk of mechanical damage of

Reasons and remedies for the agglomeration of multilayered graphene and carbon nanotubes in polymers

• Rasheed Atif and
• Fawad Inam

Beilstein J. Nanotechnol. 2016, 7, 1174–1196, doi:10.3762/bjnano.7.109

• in 1994 by Ajayan et al. [140]. Tomohiro et al. modified carbon-fiber reinforced epoxy composite with length-controlled cup-stacked CNTs and determined the mechanical properties [141]. Auad et al. produced SWNT–epoxy elastomers and showed that the nanocomposites had superior damping capacity in an

• [132]. The z-axis properties of laminated nanocomposites can also be improved by CNTs through direct reinforcement of the polymer matrix, toughening effect and fiber bridging [142]. The influence of MLG and CNTs on the mechanical, thermal, electrical, and damping properties is discussed in the

Manufacturing and investigation of physical properties of polyacrylonitrile nanofibre composites with SiO₂, TiO₂ and Bi₂O₃ nanoparticles

• Tomasz Tański,
• Wiktor Matysiak and
• Barbara Hajduk

Beilstein J. Nanotechnol. 2016, 7, 1141–1155, doi:10.3762/bjnano.7.106

• following form [38]: where n is the concentration of the atoms in the sample, e and m are charge and mass of the electron, ε0 is the electrical transmittance of vacuum, γ is the damping coefficient, ω0 and ω are, respectively, the frequency of the electron and the electromagnetic radiation. The above

Multiwalled carbon nanotube hybrids as MRI contrast agents

• Nikodem Kuźnik and
• Mateusz M. Tomczyk

Beilstein J. Nanotechnol. 2016, 7, 1086–1103, doi:10.3762/bjnano.7.102

• elimination of the radiation damping problem, have all been adapted by spectroscopists and thus have only a marginal effect on the results [60]. Relaxation acceleration is observed along with increasing temperature within the room–body temperature range [61]. However, the temperature decreases the viscosity

Advanced atomic force microscopy techniques III

• Thilo Glatzel and
• Thomas Schimmel

Beilstein J. Nanotechnol. 2016, 7, 1052–1054, doi:10.3762/bjnano.7.98

• Eva Roblegg and co-workers [20]. The local elastic stiffness and damping of individual phases in a titanium alloys was measured by using atomic force acoustic microscopy (AFAM) and mapping of contact-resonance spectra [21]. Another alloy, namely a Pt containing metallic glass, was characterized by AFM

Signal enhancement in cantilever magnetometry based on a co-resonantly coupled sensor

• Julia Körner,
• Christopher F. Reiche,
• Thomas Gemming,
• Bernd Büchner,
• Gerald Gerlach and
• Thomas Mühl

Beilstein J. Nanotechnol. 2016, 7, 1033–1043, doi:10.3762/bjnano.7.96

• oscillator model for both subsystems of our sensor approach, the simple model of a coupled harmonic oscillating system is derived as depicted in Figure 1. It consists of a spring, a mass and a damping element for each subsystem. Furthermore, there are an additional spring k3 and a damping element d3

• = k1,2/(2πf1,2)2. Equation 5 neglects any damping effects but this is a justified approximation since all our measurements are carried out under high vacuum, limiting damping to intrinsic effects due to the bending of the oscillating structures [9]. This was futhermore confirmed by comparison between the

• oscillators, each represented by a mass (m1, m2), a sping (k1, k2) and a damping element (d1, d2). The system is excited to oscillations by a periodic force with the driving angular frequency ωD = 2πfD applied to the first subsystem. Interactions between the system and external influences are modeled by an

Generalized Hertz model for bimodal nanomechanical mapping

• Aleksander Labuda,
• Marta Kocuń,
• Waiman Meinhold,
• Deron Walters and
• Roger Proksch

Beilstein J. Nanotechnol. 2016, 7, 970–982, doi:10.3762/bjnano.7.89

• , oscillation amplitude and drive amplitude. This section derives a general equation that makes no assumption about which of these variables is held fixed upon interaction with the sample. The response of a freely vibrating cantilever with effective stiffness kc, mass mc, and damping bc can be described by the

• imaginary components of both equations and solving for the driving force: In the presence of some interaction, the cantilever impedance is subject to a time-averaged change in stiffness Δk and a time-averaged change in damping Δb, such that the interaction impedance The interaction impedance is inferred

High-resolution noncontact AFM and Kelvin probe force microscopy investigations of self-assembled photovoltaic donor–acceptor dyads

• Benjamin Grévin,
• Pierre-Olivier Schwartz,
• Laure Biniek,
• Martin Brinkmann,
• Nicolas Leclerc,
• Elena Zaborova and
• Stéphane Méry

Beilstein J. Nanotechnol. 2016, 7, 799–808, doi:10.3762/bjnano.7.71

• lamellae consisting of edge-on co-oligomers (Figure 2 and Figure 5d). We note that the higher level of damping recorded over the standing domains may be reasonably attributed to the influence of the lateral alkyl side groups, which point out of the surface in the case of the edge-on oligomers (see Figure 2

• , the similarity between the damping and TEM images is remarkable when comparing Figure 4c and Figure 4d. Actually, XRD and TEM investigations [19][21] have shown that these other domains consist of flat-on lamellae (see Figure 2) and that their proportion in the film is inversely proportional to the

• length of the donor blocks. This last result is consistent with the surface morphology probed by nc-AFM (compare Figure S1a and Figure S1b in Supporting Information File 1). In the case of the longer AD3 dyad, a statistical analysis performed on large-scale damping images (by using the “flooding” tool of

Magnetic switching of nanoscale antidot lattices

• Ulf Wiedwald,
• Joachim Gräfe,
• Kristof M. Lebecki,
• Maxim Skripnik,
• Felix Haering,
• Gisela Schütz,
• Paul Ziemann,
• Eberhard Goering and
• Ulrich Nowak

Beilstein J. Nanotechnol. 2016, 7, 733–750, doi:10.3762/bjnano.7.65

• anisotropy and the exchange stiffness at 0 K for the particular material. A realistic value for the micromagnetic damping constant is in the range of 0.1 [36][37]. In case one is not interested in the dynamics but only in the equilibrium state of the system, the damping can be increased to 1. Magnetic

Coupled molecular and cantilever dynamics model for frequency-modulated atomic force microscopy

• Michael Klocke and
• Dietrich E. Wolf

Beilstein J. Nanotechnol. 2016, 7, 708–720, doi:10.3762/bjnano.7.63

• cantilever. It gives new insight into the correlation between the experimentally monitored frequency shift and cantilever damping due to the interaction between tip atoms and scanned surface. Applying the model to ionic crystals with rock salt structure two damping mechanisms are investigated, which occur

• . When the long range ionic interaction is switched off, the two damping mechanisms occur with a completely different pattern, which is explained by the energy landscape for the apex atom of the tip. In this case the adhesion hysteresis is always associated with a distinct lateral displacement of the tip

• . It is shown how this may lead to a systematic shift between the periodic patterns obtained from the frequency and from the damping signal, respectively. Keywords: atomic force microscopy; frequency-modulated atomic force microscopy (FM-AFM); energy dissipation; Introduction The physical background

Finite-size effect on the dynamic and sensing performances of graphene resonators: the role of edge stress

• Chang-Wan Kim,
• Mai Duc Dai and
• Kilho Eom

Beilstein J. Nanotechnol. 2016, 7, 685–696, doi:10.3762/bjnano.7.61

• affect the Q-factor of a graphene resonator. In order to understand the effect of edge stress on the Q-factor of a graphene resonator [29], the theoretical model described in this work has to be modified by including the intrinsic damping factors such as clamping or support loss [47][48][49] and

• thermoelastic damping loss [50], which will be considered in our future work. In conclusion, our work sheds light on the influence of edge stress on the resonant frequency and sensing performance of a graphene resonator, which allows for an insight into design rules for the effective development of graphene

Active multi-point microrheology of cytoskeletal networks

• Tobias Paust,
• Tobias Neckernuss,
• Lina Katinka Mertens,
• Ines Martin,
• Michael Beil,
• Paul Walther,
• Thomas Schimmel and
• Othmar Marti

Beilstein J. Nanotechnol. 2016, 7, 484–491, doi:10.3762/bjnano.7.42

• [5][6][7]. By exciting a particle with an oscillating force, the shear modulus at a specific frequency can be determined by measuring the response of the particle. The motion of the particle also includes information about the damping and the viscosity of the surrounding medium. This method is known

Charge and heat transport in soft nanosystems in the presence of time-dependent perturbations

• Alberto Nocera,
• Carmine Antonio Perroni,
• Vincenzo Marigliano Ramaglia and
• Vittorio Cataudella

Beilstein J. Nanotechnol. 2016, 7, 439–464, doi:10.3762/bjnano.7.39

• -dependent memory-friction kernel of the oscillator [80]. In the regime for all the modes, can be approximated as real and independent of frequency, providing the damping rate . [80] If not specified, we consider the symmetric configuration: γL = γR = γ/2. In this review, we assume that the electronic and

• always gets larger with increasing the electron–vibration coupling EP. Actually, the electron–oscillator coupling gives rise to an additional damping rate on the vibrational dynamics whose effect is to enhance the thermal conductivity . In a certain sense, due to the electron–vibration coupling, the

Length-extension resonator as a force sensor for high-resolution frequency-modulation atomic force microscopy in air

• Hannes Beyer,
• Tino Wagner and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2016, 7, 432–438, doi:10.3762/bjnano.7.38

• of frequency shift, excitation and dew point [22] over time while the sensor is retracted from the surface and Z-feedback is disabled. Frequency shift and damping correlate with environmental conditions. The resonance frequency decreases whereas the damping increases when the dew point rises. Reasons

• a long time constant (τ ≈ (1 min)), which still allows us to determine damping properties of the sample with the much faster regular amplitude-controller (τ ≈ 5 ms). The slow controller applies an offset to the Δf-signal in order to maintain the excitation setpoint and thus compensates for slow

High-bandwidth multimode self-sensing in bimodal atomic force microscopy

• Michael G. Ruppert and
• S. O. Reza Moheimani

Beilstein J. Nanotechnol. 2016, 7, 284–295, doi:10.3762/bjnano.7.26

• into account varying cross-sections but system identification based on parameter optimization must be employed to reduce modeling errors [26]. In order to arrive at a system-based model and to use frequency domain system identification, a damping term is added to Equation 13 and taking the Laplace

Determination of Young’s modulus of Sb₂S₃ nanowires by in situ resonance and bending methods

• Liga Jasulaneca,
• Raimonds Meija,
• Alexander I. Livshits,
• Juris Prikulis,
• Subhajit Biswas,
• Justin D. Holmes and
• Donats Erts

Beilstein J. Nanotechnol. 2016, 7, 278–283, doi:10.3762/bjnano.7.25

• –frequency curve is plotted for a typical single-clamped Sb2S3 NW with Q = 418. Damping ratios in resonance experiments for all NWs were in the range of 0.001–0.003, hence their contribution to the observed resonance frequencies and consequently calculated Young’s modulus values was negligible. The resonance