Reorientation of single-wall carbon nanotubes in negative anisotropy liquid crystals by an electric field

• Amanda García-García,
• Ricardo Vergaz,
• José F. Algorri,
• Gianluigi Zito,
• Teresa Cacace,
• Antigone Marino,
• José M. Otón and
• Morten A. Geday

Beilstein J. Nanotechnol. 2016, 7, 825–833, doi:10.3762/bjnano.7.74

• along the long axis (which roughly matches the director orientation) or perpendicular to the long axis. They are customarily classified as positive and negative LCs according to their dielectric anisotropy [6]. In a positive LC material, the dielectric constant along the director is larger than the

• degenerate dielectric constant perpendicular to the director. Consequently, the molecules tend to align with an applied electrical field. In a negative LC material the opposite is the case. Thus, a homogenously aligned, positive LC sandwiched between two electrodes will reorient when a sufficiently large

• LC), it may be described in impedance terms as a capacitor, where capacitance depends on the dielectric constant of the LC. The presence of SWCNTs (being conductive nanoparticles) in the LC media may change the impedance of the system. Their reorientation from planar to the substrate (i.e., the

Antibacterial activity of silver nanoparticles obtained by pulsed laser ablation in pure water and in chloride solution

• Brunella Perito,
• Emilia Giorgetti,
• Paolo Marsili and
• Maurizio Muniz-Miranda

Beilstein J. Nanotechnol. 2016, 7, 465–473, doi:10.3762/bjnano.7.40

• (blue line). In the latter case, the plasmon resonance appears blue-shifted in both ps and ns samples. Such a shift could be attributed either to a change in the dielectric constant of the liquid environment or, more reasonably, to the different oxidation grade of the NP surfaces, where the NPs obtained

Mismatch detection in DNA monolayers by atomic force microscopy and electrochemical impedance spectroscopy

• Maryse D. Nkoua Ngavouka,
• Pietro Capaldo,
• Elena Ambrosetti,
• Giacinto Scoles,
• Loredana Casalis and
• Pietro Parisse

Beilstein J. Nanotechnol. 2016, 7, 220–227, doi:10.3762/bjnano.7.20

• ), where A is the area of the electrode, d the thickness of the ssDNA layer, and ε0 and ε are the dielectric constant of vacuum and ssDNA layer, respectively. When we insert a complementary strand in the electrochemical cell, the molecular recognition between the two strands will cause a change in the

Dependence of lattice strain relaxation, absorbance, and sheet resistance on thickness in textured ZnO@B transparent conductive oxide for thin-film solar cell applications

• Kuang-Yang Kou,
• Yu-En Huang,
• Chien-Hsun Chen and
• Shih-Wei Feng

Beilstein J. Nanotechnol. 2016, 7, 75–80, doi:10.3762/bjnano.7.9

• oxide; textured ZnO; Introduction Thin-film solar cells require a transparent conductive oxide (TCO) to allow light to reach the absorber layers and create the electrical current. Due to its superior characteristics, including a wide band gap, high dielectric constant, high exciton binding energy (60

Charge injection and transport properties of an organic light-emitting diode

• Peter Juhasz,
• Juraj Nevrela,
• Michal Micjan,
• Miroslav Novota,
• Jan Uhrik,
• Lubica Stuchlikova,
• Jan Jakabovic,
• Ladislav Harmatha and
• Martin Weis

Beilstein J. Nanotechnol. 2016, 7, 47–52, doi:10.3762/bjnano.7.5

• trapping mechanism. At voltages higher than 3 V the rise of current density slows down to J V3 and follows two-carrier space-charge limited conditions (2C-SCLC), where ε is the dielectric constant of the organic film, μe and μh are electron and hole mobilities, respectively, and τ is carrier lifetime [13

Effects of electronic coupling and electrostatic potential on charge transport in carbon-based molecular electronic junctions

• Richard L. McCreery

Beilstein J. Nanotechnol. 2016, 7, 32–46, doi:10.3762/bjnano.7.4

• structures should include such electrostatic effects, including local dipoles and Mulliken charges. As an indication of the magnitude of the effect, Guerrero et al. have provided an expression for predicting the vacuum level shift, Δ, from the charge transferred, Q, the dielectric constant, ε, and an

Effects of spin–orbit coupling and many-body correlations in STM transport through copper phthalocyanine

• Benjamin Siegert,
• Andrea Donarini and
• Milena Grifoni

Beilstein J. Nanotechnol. 2015, 6, 2452–2462, doi:10.3762/bjnano.6.254

• dielectric constant εr = 2.2 in order to account for screening by frozen orbitals [12]. A table with the numerically evaluated interaction constants is found in Supporting Information File 2. Spin–orbit interaction (SOI) in the frontier orbitals basis A perturbative contribution to the bare one-body

• . Transport characteristics In this work, a tip–molecule distance of 5 Å was used and simulations were done at the temperature T = 1 K. We assumed a renormalization of the single particle energies δi = δ =1.83 eV (cf. Equation 3), an image-charge renormalization δic = 0.32 eV and a dielectric constant εr

Self-organization of gold nanoparticles on silanated surfaces

• Htet H. Kyaw,
• Salim H. Al-Harthi,
• Azzouz Sellai and
• Joydeep Dutta

Beilstein J. Nanotechnol. 2015, 6, 2345–2353, doi:10.3762/bjnano.6.242

• physical properties such as enthalpy, mechanical modulus, dielectric constant and specific volume [31]. The migration of AuNPs observed here was due to the changes in its physical properties. Upon annealing under vacuum, sample substrates reached to transition temperature, though due to the absence of

Electroviscous effect on fluid drag in a microchannel with large zeta potential

• Dalei Jing and
• Bharat Bhushan

Beilstein J. Nanotechnol. 2015, 6, 2207–2216, doi:10.3762/bjnano.6.226

• is the characteristic thickness of EDL, and is given by [5], where ε is the dielectric constant of the electrolyte, ε0 is the vacuum permittivity, kB is the Boltzmann constant, T is the absolute temperature, n0 is the bulk ionic concentration of the symmetric electrolyte, z is the valence of the ions

Kelvin probe force microscopy for local characterisation of active nanoelectronic devices

• Tino Wagner,
• Hannes Beyer,
• Patrick Reissner,
• Philipp Mensch,
• Heike Riel,
• Bernd Gotsmann and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2015, 6, 2193–2206, doi:10.3762/bjnano.6.225

• devices, such as gate oxides, not only the local dielectric constant changes, but because of their thickness also a limit is put on the minimum approachable distance in Figure 1. As a result, deliberately slow feedback settings to ensure stable operation are common practice. In this paper, we describe a

Nonlinear optical properties of near-infrared region Ag₂S quantum dots pumped by nanosecond laser pulses

• Li-wei Liu,
• Si-yi Hu,
• Yin-ping Dou,
• Tian-hang Liu,
• Jing-quan Lin and
• Yue Wang

Beilstein J. Nanotechnol. 2015, 6, 1781–1787, doi:10.3762/bjnano.6.182

• produced the lowest absorption intensity. Ag2S exhibited stronger absorption compared with CHCl3 as the pump energy increased. This can be explained by the fact that there are many impurities and electron–hole pairs in QDs. Also, when the laser interacts with QDs the dielectric constant of the medium

Radiation losses in the microwave K_u band in magneto-electric nanocomposites

• Talwinder Kaur,
• Sachin Kumar,
• Jyoti Sharma and
• A. K. Srivastava

Beilstein J. Nanotechnol. 2015, 6, 1700–1707, doi:10.3762/bjnano.6.173

• ″) and to the dielectric constant (ε′). The unsaturated coordination on the surface, nano-sized hexaferrite, the dangling bond atoms, and the enhanced surface area lead to multiple scattering resulting in the loss of radiation. Quantum size effects generate a separation among energy levels. Upon

Current–voltage characteristics of manganite–titanite perovskite junctions

• Benedikt Ifland,
• Patrick Peretzki,
• Birte Kressdorf,
• Philipp Saring,
• Andreas Kelling,
• Michael Seibt and
• Christian Jooss

Beilstein J. Nanotechnol. 2015, 6, 1467–1484, doi:10.3762/bjnano.6.152

• binding energy can be high due to the low dielectric constant of the organic semiconductors and can exceed 1 eV. Charge separation is typically hindered by a high exciton binding energy, however, it can be facilitated at a heterojunction due to formation of a more loosely bound exciton–polaron pair, which

• pairs, which are separated in the SCR. The voltage dependence of the polaron pair generation as well as the bias dependent drop of EB can both give rise to a rate r > 1. For PCMO, exciton binding energies can be neglected because of the high dielectric constant of ε = 30 [63]. By lowering the

Influence of size, shape and core–shell interface on surface plasmon resonance in Ag and Ag@MgO nanoparticle films deposited on Si/SiO_x

• Sergio D’Addato,
• Daniele Pinotti,
• Maria Chiara Spadaro,
• Guido Paolicelli,
• Vincenzo Grillo,
• Sergio Valeri,
• Luca Pasquali,
• Luca Bergamini and
• Stefano Corni

Beilstein J. Nanotechnol. 2015, 6, 404–413, doi:10.3762/bjnano.6.40

• presented in Supporting Information File 1, which reveals very similar shapes of the SDR curves. Therefore, the choice of this embedding medium dielectric constant, provided it is in the reasonable range of 1 to 1.77, is not decisive to reproduce the experimental trends (see Supporting Information File 1

• custom-written Fortran code. The optical properties of the involved media were inferred by employing either dispersive, dissipative dielectric functions () or dielectric constant (ε). In particular, the dielectric function of the substrate () and of the MgO covering layer () were obtained by a cubic

• nanometers, we additionally corrected the fit with a mean free path correction used for spheres [40]. The medium in contact with the incident radiation is assumed to be vacuum (ε1 = 1), whereas, over the range of frequencies in the selected calculations, the dielectric constant for water εH2O = 1.77 is taken

Tunable white light emission by variation of composition and defects of electrospun Al₂O₃–SiO₂ nanofibers

• Jinyuan Zhou,
• Gengzhi Sun,
• Hao Zhao,
• Xiaojun Pan,
• Zhenxing Zhang,
• Yujun Fu,
• Yanzhe Mao and
• Erqing Xie

Beilstein J. Nanotechnol. 2015, 6, 313–320, doi:10.3762/bjnano.6.29

• elements [5][6][7][8][9]. Among those materials, Al2O3 is one of the most important materials in the history of ceramics, and has been extensively applied in catalysts, coatings, microelectronics and various devices, due to its excellent physical and chemical stability, high dielectric constant, wide band

Tunable light filtering by a Bragg mirror/heavily doped semiconducting nanocrystal composite

• Ilka Kriegel and
• Francesco Scotognella

Beilstein J. Nanotechnol. 2015, 6, 193–200, doi:10.3762/bjnano.6.18

• : where ε(ω) is the bulk dielectric function at the optical frequency ω and εm is the dielectric constant of the surrounding medium. The optical extinction of ultra-small particles is dominated by absorption, but a first order correction to the quasi-static approximation should be included to account for

• composite material and to average the medium dielectric function according to the multiple values of the constituents of the composite material. The effective dielectric function (εeff) of a film of ITO NCs can be described by the MG-EMA as follows: where εm is the medium dielectric constant, εi is the

Intake of silica nanoparticles by giant lipid vesicles: influence of particle size and thermodynamic membrane state

• Florian G. Strobl,
• Florian Seitz,
• Christoph Westerhausen,
• Armin Reller,
• Adriano A. Torrano,
• Christoph Bräuchle,
• Achim Wixforth and
• Matthias F. Schneider

Beilstein J. Nanotechnol. 2014, 5, 2468–2478, doi:10.3762/bjnano.5.256

• , following [33] and assuming interaction at constant potential (high salt limit), an upper limit for the double layer interaction gdl can be approximated by the Hogg–Healy–Fuerstenau equation: Here, d is the distance from the silica surface, ε0εr the dielectric constant of the medium and l the Debye length

Liquid-phase exfoliated graphene: functionalization, characterization, and applications

• Mildred Quintana,
• Jesús Iván Tapia and
• Maurizio Prato

Beilstein J. Nanotechnol. 2014, 5, 2328–2338, doi:10.3762/bjnano.5.242

• , good conductivity, recyclability, and the high dielectric constant of ionic liquids induce the exfoliation of graphite by weakening the π–π stacking interactions. Indeed, the use of ionic liquids is considered a highly versatile and industrially scalable method for the preparation of graphene

Effect of channel length on the electrical response of carbon nanotube field-effect transistors to deoxyribonucleic acid hybridization

• Hari Krishna Salila Vijayalal Mohan,
• Jianing An,
• Yani Zhang,
• Chee How Wong and
• Lianxi Zheng

Beilstein J. Nanotechnol. 2014, 5, 2081–2091, doi:10.3762/bjnano.5.217

• capacitance per unit length of the nanotube, (when modeled as a cylinder on a planar substrate) is given by where ε0 is the permittivity of free space (8.8542 × 10−12 Fm−1), εr is the dielectric constant of the SiO2 gate insulator (≈3.9), tox is the SiO2 thickness, r is the radius of the nanotube, and L is

Optical properties and electrical transport of thin films of terbium(III) bis(phthalocyanine) on cobalt

• Peter Robaschik,
• Pablo F. Siles,
• Daniel Bülz,
• Peter Richter,
• Manuel Monecke,
• Michael Fronk,
• Svetlana Klyatskaya,
• Daniel Grimm,
• Oliver G. Schmidt,
• Mario Ruben,
• Dietrich R. T. Zahn and
• Georgeta Salvan

Beilstein J. Nanotechnol. 2014, 5, 2070–2078, doi:10.3762/bjnano.5.215

• of the organic film, ε is the relative dielectric constant, ε0 is the permittivity of free space, µ is the charge carrier mobility and V is the applied voltage. From the ohmic-like regime (see Figure 7b) we obtained parameters of σ/L equal to 1.38 and 0.97 kA/cm2 V for the samples of 20 and 80 nm

• , respectively. For the dielectric constant we consider a minimum value of ε = 4.5, which is the real part of the dielectric function at the lowest photon energy (1.3 eV) used in our ellipsometry experiment (see Figure 2). As a maximum value for the dielectric constant we used ε = 13, which was previously

• and the dielectric constant considered. The AFM-based approach implemented here allows important transport properties such as current density homogeneity and the local charge carrier mobility to be quantified. The nanoscale resolution achieved here for the characterization of organic systems such as

Experimental techniques for the characterization of carbon nanoparticles – a brief overview

• Wojciech Kempiński,
• Szymon Łoś,
• Mateusz Kempiński and
• Damian Markowski

Beilstein J. Nanotechnol. 2014, 5, 1760–1766, doi:10.3762/bjnano.5.186

• on the dielectric constant of the separator [4][8] and in ACFs its value seems to be influenced by the existence of guest molecules inside the pores. It has been shown that the T0 parameter increases with the value of the dipole moment of the guest molecules adsorbed within the ACF pores [44]. This

Controlling the dispersion of supported polyoxometalate heterogeneous catalysts: impact of hybridization and the role of hydrophilicity–hydrophobicity balance and supramolecularity

• Gijo Raj,
• Colas Swalus,
• Eglantine Arendt,
• Pierre Eloy,
• Michel Devillers and
• Eric M. Gaigneaux

Beilstein J. Nanotechnol. 2014, 5, 1749–1759, doi:10.3762/bjnano.5.185

• Langmuir–Blodgett technique, exhibited a high dielectric constant, which makes them promising candidates for applications in future memory storage, and hybrid (organic–inorganic) electronic devices. Often cationic surfactants such as DODA were used as host organic matrix to synthesize organic–inorganic

Non-covalent and reversible functionalization of carbon nanotubes

• Antonello Di Crescenzo,
• Valeria Ettorre and
• Antonella Fontana

Beilstein J. Nanotechnol. 2014, 5, 1675–1690, doi:10.3762/bjnano.5.178

• dipole–dipole or π-orbital overlap interactions may not account for an equivalent dispersion performance, neither equally polar solvents such as acetonitrile (dielectric constant 36.00) and DMSO (dielectric constant 46.71) or 1,2-dichlorobenzene able to give higher π-orbital overlap interactions despite

• being less polar (dielectric constant 10.36) [43] than DEA. An alternative strategy to favor CNTs dispersion in organic solvents is to coat CNTs with a dispersant phase, usually a molecule characterized by a high affinity towards nanotube sidewalls and at the same time particularly soluble in the

The influence of molecular mobility on the properties of networks of gold nanoparticles and organic ligands

• Edwin J. Devid,
• Paulo N. Martinho,
• M. Venkata Kamalakar,
• Úna Prendergast,
• Christian Kübel,
• Tibebe Lemma,
• Jean-François Dayen,
• Tia. E. Keyes,
• Bernard Doudin,
• Mario Ruben and
• Sense Jan van der Molen

Beilstein J. Nanotechnol. 2014, 5, 1664–1674, doi:10.3762/bjnano.5.177

• volume. UV–vis spectroscopy Ultraviolet-visible (UV–vis) spectroscopy is performed to gain insight into the optical properties of these molecule–gold nanoparticle arrays, and specifically to investigate the influence of the S-BPP molecules on the effective dielectric constant. Metal nanoparticles exhibit

• dielectric constant of the medium εeff that takes into account both the presence of the surrounding medium and the neighbouring nanoparticles [31][32][33]. The resonance condition is then given by: Here, ωsp denotes the frequency of the SPR and εm is the dielectric constant of the medium surrounding the

• now be checked for consistency. Since we are able to estimate f from the electron microscopy images, for both the C8–gold nanoparticle array and the Au-NP–S-BPP array, we can apply the Maxwell–Garnett theory to estimate the dielectric constant εm in these arrays as well. Indeed, we find approximately

Current state of laser synthesis of metal and alloy nanoparticles as ligand-free reference materials for nano-toxicological assays

• Christoph Rehbock,
• Jurij Jakobi,
• Lisa Gamrad,
• Selina van der Meer,
• Daniela Tiedemann,
• Ulrike Taylor,
• Wilfried Kues,
• Detlef Rath and
• Stephan Barcikowski

Beilstein J. Nanotechnol. 2014, 5, 1523–1541, doi:10.3762/bjnano.5.165

• been known that during measurements of the electrokinetic potentials in aqueous solutions the temperature dependence of conductivity, dielectric constant and viscosity are negligible up to a temperature of 343 K [106]. Based on these simplified assumptions, at room temperature (T = 293 K) a zeta