Nanoscale mapping of dielectric properties based on surface adhesion force measurements

• Ying Wang,
• Yue Shen,
• Xingya Wang,
• Zhiwei Shen,
• Bin Li,
• Jun Hu and
• Yi Zhang

Beilstein J. Nanotechnol. 2018, 9, 900–906, doi:10.3762/bjnano.9.84

• sample in the height image. In addition, by comparing Figure 2a and Figure 2e, we can see the RGO sheet was not damaged by the biased AFM tip. This is because the increase of adhesion caused by the applied tip bias is no more than 20 nN, which is about two orders of magnitude lower than the threshold

Effect of ferroelectric BaTiO₃ particles on the threshold voltage of a smectic A liquid crystal

• Abbas R. Imamaliyev,
• Mahammadali A. Ramazanov and
• Shirkhan A. Humbatov

Beilstein J. Nanotechnol. 2018, 9, 824–828, doi:10.3762/bjnano.9.76

• ferroelectric BaTiO3 particles on the planar–homeotropic transition threshold voltage in smectic A liquid crystals consisting of p-nitrophenyl p-decyloxybenzoate and 4-cyano-4′-pentylbiphenyl were studied by using capacitance–voltage (C–V) measurements. It was shown that the BaTiO3 particles significantly

• reduce the threshold voltage. The obtained result is explained by two factors: an increase of dielectric anisotropy of the liquid crystals and the formation of a strong electric field near polarized particles of BaTiO3. It was shown that the role of the second factor is dominant. The explanations of some

• features observed in the C–V characteristics are given. Keywords: colloidal systems; dielectric permittivity; ferroelectric BaTiO3 particles; smectic A liquid crystals; threshold voltage; Introduction Interest in liquid crystals (LC) as a unique state of matter arises not only from a scientific point of

Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces

• Sven Oras,
• Sergei Vlassov,
• Marta Berholts,
• Rünno Lõhmus and
• Karine Mougin

Beilstein J. Nanotechnol. 2018, 9, 660–670, doi:10.3762/bjnano.9.61

• meniscus and Fadh = Fss. From a certain threshold humidity a single meniscus forms giving rise to a larger but constant adhesion force. Although AFM tip in our experiments constantly moves relative to Au NPs, the velocities of the tip are not high enough to completely exclude the formation of capillary

Towards 3D crystal orientation reconstruction using automated crystal orientation mapping transmission electron microscopy (ACOM-TEM)

• Aaron Kobler and
• Christian Kübel

Beilstein J. Nanotechnol. 2018, 9, 602–607, doi:10.3762/bjnano.9.56

• above a given threshold. This can be visualized in an inverse pole figure containing the cross-correlation indices of all simulated orientations with one experimental diffraction pattern (Figure 1a, dark areas indicate high cross-correlation indices). It has been shown that the template matching result

Electron interactions with the heteronuclear carbonyl precursor H₂FeRu₃(CO)₁₃ and comparison with HFeCo₃(CO)₁₂: from fundamental gas phase and surface science studies to focused electron beam induced deposition

• Ragesh Kumar T P,
• Paul Weirich,
• Lukas Hrachowina,
• Marc Hanefeld,
• Ragnar Bjornsson,
• Helgi Rafn Hrodmarsson,
• Sven Barth,
• D. Howard Fairbrother,
• Michael Huth and
• Oddur Ingólfsson

Beilstein J. Nanotechnol. 2018, 9, 555–579, doi:10.3762/bjnano.9.53

• the threshold energy for the individual processes at the PBE0 [74][75] /ma-def2 TZVP [76][77] level of theory. We have previously compared the performance of PB86 to that of PBE0 for threshold calculations in DEA to HFeCo3(CO)12 [39] and found that while PB86 reproduced the structural parameters from

• the X-ray diffraction (XRD) measurements very well, this functional overestimated the threshold energies significantly, PBE0, on the other hand delivered threshold energies in good agreement with our experimental appearance energies. We thus use the threshold energies calculated at the PBE0 level of

• ]− and [M − Fe(CO)2]− with appreciable intensity on the [M − Fe(CO)3]− fragment. Charge retention on the remaining Ru3(CO)n base plane moiety is also observed along with further CO loss, up to 11 CO in total, as shown in Figure 4. Based on our threshold calculations we attribute these channels to the

Dynamic behavior of nematic liquid crystal mixtures with quantum dots in electric fields

• Emil Petrescu,
• Cristina Cirtoaje and
• Octavian Danila

Beilstein J. Nanotechnol. 2018, 9, 399–406, doi:10.3762/bjnano.9.39

• than the Fréedericksz transition threshold [18][19] is applied transversely to a planar liquid crystal cell, the molecules change their orientation tending to align their director in parallel to the field. This reorientation is illustrated by an intensity variation of a laser beam crossing through the

• -based device parameters. Theoretical Background When a nematic liquid crystal with positive dielectric anisotropy is exposed to an electric field, and if the intensity of the field is higher than the Fréedericksz transition threshold, the molecular director changes its orientation, trying to align in

• threshold, the deviation angle is very small and the free energy caused by the elastic forces is: where K1 and K3 are the splay and bent elastic constants and θz = ∂θ/∂z. Due to the presence of the QDs, the electric properties of the mixture change. Hence, instead of perpendicular dielectric permittivity

Electron interaction with copper(II) carboxylate compounds

• Michal Lacko,
• Peter Papp,
• Iwona B. Szymańska,
• Edward Szłyk and
• Štefan Matejčík

Beilstein J. Nanotechnol. 2018, 9, 384–398, doi:10.3762/bjnano.9.38

• discussed COOH+ ion that is assumed to be formed via interaction of residual water molecules with the sample. Dissociation of first carboxylate ligand from [Cu2(µ-O2CC2F5)4] molecule was detected with AE1615 = 11.4 eV and with a second threshold at AE2615 = 15.7 eV. Dissociation of second ligand occurs with

• AE1452 = 9.7 eV and again with a second threshold at AE2452 = 15.2 eV. Dissociation of third ligand starts at AE289 = 11.9 eV without any other distinguishable threshold. The origin of the second threshold can be a) an energetically higher excited state of the same fragment, b) a different stoichiometric

• eV, respectively. Thus dissociation does not follow a simple one by one ligand loss mechanism. The similar values of AE615 and AE289 may be explained only in the case, that while the formation of Cu2(O2CC2F5)3+ ion occur as a dissociation process from the parent cation, the second threshold at 15.2

Review: Electrostatically actuated nanobeam-based nanoelectromechanical switches – materials solutions and operational conditions

• Liga Jasulaneca,
• Jelena Kosmaca,
• Raimonds Meija,
• Jana Andzane and
• Donats Erts

Beilstein J. Nanotechnol. 2018, 9, 271–300, doi:10.3762/bjnano.9.29

• controlling the electrical current. NEM switches have attracted attention as low-power [1] devices, demonstrating abrupt on/off switching characteristics and minimized sub-threshold swing, as well as reduced leakage currents leading to improved on/off ratios [2]. In the context of existing

Dynamic behavior of a nematic liquid crystal with added carbon nanotubes in an electric field

• Emil Petrescu and
• Cristina Cirtoaje

Beilstein J. Nanotechnol. 2018, 9, 233–241, doi:10.3762/bjnano.9.25

• molecules and align themselves parallel with the long axis of the nematic [12][13][14]. Under the action of an external magnetic or electric field above a critical threshold, nematic molecules collectively change their orientation. This is called the Fréedericksz transition [15][16] and the molecular

• -cyano-4’-pentylbiphenyl (5CB) liquid crystal (LC). Theoretical Background When a liquid crystal with positive dielectric anisotropy is exposed to an external electric field higher than the critical Fréedericksz transition threshold, its molecules have a tendency to orient their director parallel to the

• Dierking and co-workers [13][14] proved an alignment of CNTs parallel to the liquid crystal molecules, so we may assume that the anchoring angle α is neglectable. Thus, Equation 11 becomes: When exposed to an external electric field higher than the critical Fréedericksz transition threshold the molecules

Comparative study of post-growth annealing of Cu(hfac)₂, Co₂(CO)₈ and Me₂Au(acac) metal precursors deposited by FEBID

• Marcos V. Puydinger dos Santos,
• Aleksandra Szkudlarek,
• Artur Rydosz,
• Carlos Guerra-Nuñez,
• Fanny Béron,
• Kleber R. Pirota,
• Stanislav Moshkalev,
• José Alexandre Diniz and
• Ivo Utke

Beilstein J. Nanotechnol. 2018, 9, 91–101, doi:10.3762/bjnano.9.11

• . In particular, the size of the metal agglomerates of all deposits was estimated from high-magnification SEM images (see Figure 1), using ImageJ software applying a fast Fourier transform (FFT) bandpass filter to enhance grain boundaries and a contrast-threshold algorithm to calculate the agglomerate

Electron-driven and thermal chemistry during water-assisted purification of platinum nanomaterials generated by electron beam induced deposition

• Ziyan Warneke,
• Markus Rohdenburg,
• Jonas Warneke,
• Janina Kopyra and
• Petra Swiderek

Beilstein J. Nanotechnol. 2018, 9, 77–90, doi:10.3762/bjnano.9.10

• of CH4 which is supported by the very small amount of C2H6 production as also observed here. The latter would be expected to result from recombination of CH3 radicals that have dissociated from the precursor. When electron irradiation is performed at E0 well above the ionization threshold, as in the

• data for DEA and EI of MeCpPtMe3 as well as a detailed understanding of the fragmentation mechanisms following EI do not exist to the best of our knowledge. Furthermore, neutral dissociation (ND), a non-resonant process with a threshold comparable to EI and leading to the formation of uncharged

• when the electron beam is switched on in the presence of H2O. Electron exposure of condensed H2O and clusters of H2O at E0 above the ionization threshold is known to induce the following proton transfer [27] and thereby yields OH radicals. As MeCpPtMe3 tends to lose its cyclopentadienyl ligand when

Response under low-energy electron irradiation of a thin film of a potential copper precursor for focused electron beam induced deposition (FEBID)

• Leo Sala,
• Iwona B. Szymańska,
• Céline Dablemont,
• Anne Lafosse and
• Lionel Amiaud

Beilstein J. Nanotechnol. 2018, 9, 57–65, doi:10.3762/bjnano.9.8

• irradiation by different processes. The most efficient process at high energy is the dissociative ionization (DI), above the ionization threshold. It produces a neutral fragment and a cation, which can be eventually neutralized. At lower energy, and above the electronic excitation threshold, the most

A robust AFM-based method for locally measuring the elasticity of samples

• Alexandre Bubendorf,
• Stefan Walheim,
• Thomas Schimmel and
• Ernst Meyer

Beilstein J. Nanotechnol. 2018, 9, 1–10, doi:10.3762/bjnano.9.1

• third phase, the tip geometry and the increase of the indentation depth result in a larger increase in the contact area than that produced by the applied normal force, thus decreasing the stress on the sample surface. When the stress decreases below a threshold value, σ0, the sample starts deforming

• stress. When the σ is below a threshold value, the surface begins to deform elastically. The elastic phase is characterized by a linear relation between the frequency shifts Δf1 and Δf2 and the Z-displacement of the piezoelectric scanner. A linear relation between the measured normal force FN,meas and

• below a threshold value σ0, the deformation becomes elastic. The red area of the tip apex describes the contact area of the tip. The striped area shows the region of the sample plastically deformed during indentation. The arrow at the tip apex represents the applied normal force FN; the arrows on the

Magnetic field induced orientational transitions in liquid crystals doped with carbon nanotubes

• Danil A. Petrov,
• Pavel K. Skokov and
• Alexander N. Zakhlevnykh

Beilstein J. Nanotechnol. 2017, 8, 2807–2817, doi:10.3762/bjnano.8.280

• , one should expect decreasing of the threshold field of the magnetic Fréedericksz transition, which is confirmed by experiment [18][19], as well as a decrease in the electric field of the Fréedericksz transition [11][14][20][21][22]. Along with this, there are experimental studies devoted to the

• Fréedericksz transition threshold in comparison with the pure NLC. These two mechanisms of the field influence on the suspension prove to be interdependent due to the orientational interaction of CNTs with the LC matrix. In the framework of continuum theory, the equilibrium state of the suspension corresponds

• threshold value hc, a transition to the angular phase occurs (Figure 2b) with distorted orientational structures of n and m. By analogy with pure LCs this transition can be called the Fréedericksz transition. The distortions of the orientational structure are small [, ] in the vicinity of hc, and the

Electro-optical characteristics of a liquid crystal cell with graphene electrodes

• Nune H. Hakobyan,
• Hakob L. Margaryan,
• Valeri K. Abrahamyan,
• Vladimir M. Aroutiounian,
• Arpi S. Dilanchian Gharghani,
• Amalya B. Kostanyan,
• Timothy D. Wilkinson and
• Nelson Tabirian

Beilstein J. Nanotechnol. 2017, 8, 2802–2806, doi:10.3762/bjnano.8.279

• (high voltage, V >> Vth) and slow switching (the voltage is close to the threshold, V < 5Vth). In the fast switching mode (Figure 7), under the influence of a strong electric field, the bulk and boundary layers of the LC are involved in the reorientation process. This reduces the relaxation time due to

Thermo- and electro-optical properties of photonic liquid crystal fibers doped with gold nanoparticles

• Agata Siarkowska,
• Miłosz Chychłowski,
• Daniel Budaszewski,
• Bartłomiej Jankiewicz,
• Bartosz Bartosewicz and
• Tomasz R. Woliński

Beilstein J. Nanotechnol. 2017, 8, 2790–2801, doi:10.3762/bjnano.8.278

• properties of LCs as they can influence, for example, the LC response time and decrease the Freedericksz threshold voltage [6][7][8]. Promising results were reported for metallic (mostly gold and silver), ferroelectric and dielectric NPs [9][10][11][12]. It appeared that NP/LC molecule size matching can

• nematic–isotropic phase transition temperature [21][22], but with a specific surface coating, the effect can be reversed [23]. The presence of Au NPs in an LC has proven to influence the response time and lower the threshold voltage [24][25][26][27][28]. In this paper we compare four different

• transition temperature and threshold voltage. The latter effect also confirms our observations. As can be seen in Table 2, where the presence of metallic NPs reduced the threshold voltage needed to reorient the LC molecules. For undoped PLCFs, the molecules start switching above 2.4 V/µm and for Au-doped LCs

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

• threshold of approximately 0.24, the amplitude difference starts to decrease. Such a characteristic has also been noted in a previous publication. The higher harmonics were found to have an inverted U-shape dependence on the tip–sample gap [32]. Despite the deviation in the quantitative values, the

The rational design of a Au(I) precursor for focused electron beam induced deposition

• Ali Marashdeh,
• Thiadrik Tiesma,
• Niels J. C. van Velzen,
• Sjoerd Harder,
• Remco W. A. Havenith,
• Jeff T. M. De Hosson and
• Willem F. van Dorp

Beilstein J. Nanotechnol. 2017, 8, 2753–2765, doi:10.3762/bjnano.8.274

• . While four molecules in the unit have strong aurophilic interactions, two molecules have Au–Au distances of more than 4.0 Å. These two should basically be considered monomeric. We observe that the threshold for desorption is relatively low for these more loosely bound molecules. As some of the MeAuPMe3

Exploring wear at the nanoscale with circular mode atomic force microscopy

• Olivier Noel,
• Aleksandar Vencl and
• Pierre-Emmanuel Mazeran

Beilstein J. Nanotechnol. 2017, 8, 2662–2668, doi:10.3762/bjnano.8.266

• proportional to the applied load. For small applied loads, the wear rate is almost zero and it is necessary to reach a threshold load (of approximately 50 nN) to get a significant wear volume. Conclusion This paper reported on an original approach for generating and quantitatively measuring nanoscale wear

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

• NPs affects the percolation threshold, the critical volume fraction of particles required to provide metallic behavior in layers [60][61]. Surface ligands have been tailored to provide interactions that foster organization into structures with sufficient connectivity and provide conductive pathways

• the copper seeds and favored the crystal growth of the high-surface-energy ends of the rods [21]. Table 1 summarizes important ligands that have been used to direct the shape of metal nanoparticles. The geometry of metal nanostructures can affect the percolation threshold and, thus, the conductivity

• ligands affect the sintering process. In one example, the conductivity of films prepared from silver nanoparticles with dodecylamine began to rise significantly at 108 °C, whereas dodecylthiol led to an onset at 238 °C [126]. The weaker Ag–amine bond may explain the lower temperature threshold

Interactions of low-energy electrons with the FEBID precursor chromium hexacarbonyl (Cr(CO)₆)

• Jusuf M. Khreis,
• João Ameixa,
• Filipe Ferreira da Silva and
• Stephan Denifl

Beilstein J. Nanotechnol. 2017, 8, 2583–2590, doi:10.3762/bjnano.8.258

• molecules were performed with proposed fragmentation pathways and determined threshold energies for the formed cationic species [17]. Electronic energy levels of metal carbonyls and metal cyanides were described by Gray and Beach [18], and the molecular orbitals were calculated by Johnson and Klemperer

• electron energy is higher than the ionization threshold of the molecule, electron ionization and dissociation is energetically possible. The formation of both positive and negative ions, from the molecular ion as well as from intermediate ions formed, may also occur in a slow reaction extending to the

Robust nanobubble and nanodroplet segmentation in atomic force microscope images using the spherical Hough transform

• Yuliang Wang,
• Tongda Lu,
• Xiaolai Li,
• Shuai Ren and
• Shusheng Bi

Beilstein J. Nanotechnol. 2017, 8, 2572–2582, doi:10.3762/bjnano.8.257

• . By applying image flattening, an AFM image with improved contrast can be obtained, as shown in Figure 1b. Today, the most widely applied segmentation method is the thresholding method [19][26] in which the choice of threshold value is a matter of great concern due to the uneven background of AFM

• images. A too small threshold value will cause over-segmentation, while a too large one will cause under-segmentation and thus the under-estimation of the NB/ND height and volume. For the image shown in Figure 1a, the segmentation result using the thresholding method is unsatisfactory. Only NBs in the

• higher region are detected, while the rest are all ignored. For these kind of images, they must be flattened to get improved segmentation result in the thresholding method (Figure 1b). For the flattened images, if proper threshold values are applied, they can be correctly detected, as shown in the left

Amplified cross-linking efficiency of self-assembled monolayers through targeted dissociative electron attachment for the production of carbon nanomembranes

• Sascha Koch,
• Christopher D. Kaiser,
• Paul Penner,
• Michael Barclay,
• Lena Frommeyer,
• Daniel Emmrich,
• Patrick Stohmann,
• Tarek Abu-Husein,
• Andreas Terfort,
• D. Howard Fairbrother,
• Oddur Ingólfsson and
• Armin Gölzhäuser

Beilstein J. Nanotechnol. 2017, 8, 2562–2571, doi:10.3762/bjnano.8.256

• well below 10 eV is significant at threshold (i.e., close to 0 eV), and has a high energy tail, the extension of which depends on the energy of the primary irradiation and the nature of the substrate (see, e.g., [18][19][20] and references therein). For both silver and copper at a primary electron

• energy of 30 eV, the secondary electron yield peaks below 1 eV with a full-width half-maximum (FWHM) of about 3.4 and 5.6 eV, respectively. This is considered to be a significant contribution at threshold and a tail at higher energy [21]. The situation may be expected to be similar as that of gold [22

• fragment (X) exceeds the respective bond dissociation energy (BDE(M−X)); Here ΔHrxn is the reaction enthalpy for the bond rupture, which is approximately equal to the respective threshold energy (Eth). For the higher halogens Cl, Br and I, the BDE(C6H5−X) in the respective halo-benzenes decreases

Ferrocholesteric–ferronematic transitions induced by shear flow and magnetic field

• Dmitriy V. Makarov,
• Alexander A. Novikov and
• Alexander N. Zakhlevnykh

Beilstein J. Nanotechnol. 2017, 8, 2552–2561, doi:10.3762/bjnano.8.255

• parameter. Phase diagrams of ferrocholesteric–ferronematic transition and the pitch of the ferrocholesteric helix as functions of the material and the governing parameters are calculated. We find out that imposing a shear flow leads to a shift of the magnetic field threshold. The value of the critical

• begins to increase strongly when the critical values hc or uc are approached. Finally, the values of the pitch diverge. As can be seen in the phase diagram in Figure 5, the threshold values hc < hc0 and uc < uc0. Here, hc0 is the critical value of the magnetic field strength of the cholesteric–nematic

PTFE-based microreactor system for the continuous synthesis of full-visible-spectrum emitting cesium lead halide perovskite nanocrystals

• Chengxi Zhang,
• Weiling Luan,
• Yuhang Yin and
• Fuqian Yang

Beilstein J. Nanotechnol. 2017, 8, 2521–2529, doi:10.3762/bjnano.8.252

• different precursor ratios of Br/I. In general, the emission wavelength for the PL peak increases with increasing reaction temperature, showing a red shift for all the prepared alloyed CsPbBrxI3−x QDs. For the QDs with the Br/I ratio of 2:1, 3:1, and 1:2, there is a threshold temperature whereby the further

• :2, there was a threshold temperature at which a further increase in the reaction temperature had no effect on the emission wavelength for the corresponding PL peak. A slight blue shift was found for the QDs with the Br/I ratio of 1:3 for reaction temperatures larger than 100 °C. Increasing the