Optical near-field mapping of plasmonic nanostructures prepared by nanosphere lithography

• Gitanjali Kolhatkar,
• Alexandre Merlen,
• Jiawei Zhang,
• Chahinez Dab,
• Gregory Q. Wallace,
• François Lagugné-Labarthet and
• Andreas Ruediger

Beilstein J. Nanotechnol. 2018, 9, 1536–1543, doi:10.3762/bjnano.9.144

• periodicity of ≈3 µm−1 in the Fourier (2D reciprocal) space. The anisotropy of this pattern is also reflected in the 2D fast Fourier transform (FFT) of the optical image, presented in Figure 1c. In addition, those patterns vary with the polarization, and with the laser focus. Thus, these oscillation patterns

• and post-data treatment is imperative to retrieve the near-field information. We used this protocol to study the optical near-field properties of gold nanotriangle arrays with two different laser wavelengths of 632.8 nm and 532.1 nm, using the same pixel size (20 nm) and a p-polarization, as presented

• resolution. It is worthwhile mentioning that the cut-off of the filtering process ultimately determines the spatial resolution: a compromise needs to be found to remove the high frequency noise without removing the near-field signal as noticed above. Surprisingly, no polarization effect was observed. Our

Cathodoluminescence as a probe of the optical properties of resonant apertures in a metallic film

• Kalpana Singh,
• Evgeniy Panchenko,
• Babak Nasr,
• Amelia Liu,
• Lukas Wesemann,
• Timothy J. Davis and
• Ann Roberts

Beilstein J. Nanotechnol. 2018, 9, 1491–1500, doi:10.3762/bjnano.9.140

• space and time [38], and hence, an electron beam can induce a time-varying polarization in an adjacent material leading to optical excitation. Optical resonances can be probed by studying either the loss in the energy of the electrons (through electron energy loss spectroscopy, EELS) [38][39] or the

Excitation of nonradiating magnetic anapole states with azimuthally polarized vector beams

• Aristeidis G. Lamprianidis and
• Andrey E. Miroshnichenko

Beilstein J. Nanotechnol. 2018, 9, 1478–1490, doi:10.3762/bjnano.9.139

• experimentally [24][32]. It turns out, that if we change the polarization from radial to azimuthal, then, only magnetic harmonics will be present. Thus, using such an illumination scheme will be ideal to test the possibility of the magnetic anapole excitation. An excited magnetic anapole is expected to have

Tailoring polarization and magnetization of absorbing terahertz metamaterials using a cut-wire sandwich structure

• Hadi Teguh Yudistira,
• Shuo Liu,
• Tie Jun Cui and
• Han Zhang

Beilstein J. Nanotechnol. 2018, 9, 1437–1447, doi:10.3762/bjnano.9.136

• this work, we designed, fabricated and characterized a cut-wire sandwich device capable of tailoring the polarization and magnetization separately, thereby providing a promising recipe for achieving specific application objectives, such as a high-performance absorber. Accumulated charges effectively

• provided the polarization at the edge of cut-wires, and the surface current density on the cut-wires at top and bottom layers effectively generated the magnetization. By controlling and optimizing the geometrical configurations of the entire sandwich device (without lateral misalignment), the impedance

• other frequency ranges because polarization and magnetization can now be selectively controlled in a straightforward manner. Keywords: absorber; cut-wire; metamaterial; terahertz; Introduction The terahertz spectrum is located between the infrared and microwave spectrum. This part of the spectrum has

Electrostatically actuated encased cantilevers

• Benoit X. E. Desbiolles,
• Gabriela Furlan,
• Adam M. Schwartzberg,
• Paul D. Ashby and
• Dominik Ziegler

Beilstein J. Nanotechnol. 2018, 9, 1381–1389, doi:10.3762/bjnano.9.130

• frequency of the electrical drive signal matches the mechanical resonance frequency of the cantilever. In sub-harmonic mode, the excitation applies an ac drive voltage at half of the mechanical resonance frequency which results in more stable oscillation unaffected by fluctuations of polarization or

Interplay between pairing and correlations in spin-polarized bound states

• Szczepan Głodzik,
• Aksel Kobiałka,
• Anna Gorczyca-Goraj,
• Andrzej Ptok,
• Grzegorz Górski,
• Maciej M. Maśka and
• Tadeusz Domański

Beilstein J. Nanotechnol. 2018, 9, 1370–1380, doi:10.3762/bjnano.9.129

• and interactions. We explore the influence of the spin–orbit coupling on energies, polarization and spatial patterns of the bound (Yu–Shiba–Rusinov) states of magnetic impurities in a two-dimensional square lattice. We also address the peculiar bound states in the proximitized Rashba chain, resembling

• the Majorana quasiparticles, focusing on their magnetic polarization that has been recently reported by S. Jeon et al. (Science 2017, 358, 772). Finally, we study leakage of these polarized Majorana quasiparticles into side-attached nanoscopic regions and confront them with the subgap Kondo effect

• pairing driven by the proximity effect [4][5]. Cooper pairs easily penetrate the nanoscopic impurities, inducing the bound (Yu–Shiba–Rusinov) states that manifest the local pairing in coexistence with magnetic polarization. Such bound states have been observed in various systems [6][7][8][9][10][11][12

New 2D graphene hybrid composites as an effective base element of optical nanodevices

• Olga E. Glukhova,
• Igor S. Nefedov,
• Alexander S. Shalin and
• Мichael М. Slepchenkov

Beilstein J. Nanotechnol. 2018, 9, 1321–1327, doi:10.3762/bjnano.9.125

• and z < 0, respectively, n is a normal vector to the surface. In future, we intend to solve the boundary-value problem for the two separate cases of the polarization of the incident radiation, either parallel to the plane of the incident radiation (p-polarization) or normal (s-polarization). A well

• -polarization where Z0 is defined for the p-polarized wave as Z0 = Ex/Hy = η·cosθ, and for the s-polarized wave as Z0 = −Ey/Hy = η/cosθ, where θ is the angle of incidence η = 120π Ω is the input impedance of vacuum. Taking into account expressions for the reflection and transmission coefficients, is it possible

• spectra are similar with only minor changes. The calculation results of the absorption of electromagnetic waves of the CNT–graphene hybrid nanocomposite are presented in Figure 5 and Figure 6. These figures show two cases of the polarization for different topological models of the hybrid nanocomposite

Formation and development of nanometer-sized cybotactic clusters in bent-core nematic liquid crystalline compounds

• Yuri P. Panarin,
• Sithara P. Sreenilayam,
• Jagdish K. Vij,
• Anne Lehmann and
• Carsten Tschierske

Beilstein J. Nanotechnol. 2018, 9, 1288–1296, doi:10.3762/bjnano.9.121

• are members of a homologous series of 4-cyanoresorcinol. The molecular structure and the phase sequence of the compounds are shown in Figure 1. The first compound (BCN66) with a large flexoelectric polarization [52] is a member of the homologue series consisting of a bent core of five aromatic rings

Surface characterization of nanoparticles using near-field light scattering

• Eunsoo Yoo,
• Yizhong Liu,
• Chukwuazam A. Nwasike,
• Sebastian R. Freeman,
• Brian C. DiPaolo,
• Bernardo Cordovez and
• Amber L. Doiron

Beilstein J. Nanotechnol. 2018, 9, 1228–1238, doi:10.3762/bjnano.9.114

• output edge where transmitted light is collected by a photodetector. Three polarization-maintaining optical fibers are supported by a silicon v-groove array and are optically aligned to the three waveguides permanently bonded to the chips. Each chip has two through-holes for fluidic access. Fluid lines

Inverse proximity effect in semiconductor Majorana nanowires

• Alexander A. Kopasov,
• Ivan M. Khaymovich and
• Alexander S. Mel'nikov

Beilstein J. Nanotechnol. 2018, 9, 1184–1193, doi:10.3762/bjnano.9.109

• separates the regimes with trivial and nontrivial topological properties of the system [3][4][18]. Further increase in the magnetic field is known to suppress the proximity effect since in the absence of the spin–orbit coupling the Fermi level crosses the only energy branch with a complete spin polarization

• along the magnetic field direction. The nonzero spin–orbit coupling destroys this spin polarization mixing different spin projections and resulting in a nonzero induced superconducting gap in the wire of approximately αΔind/gβH, where Δind is the induced superconducting order parameter in the wire, and

• standard paramagnetic effect. In contast, in the topologically nontrivial regime Tc increases (with or without initial decay at small fields). This increase in the critical temperature originates from the reduction of the proximity effect due to almost pure spin polarization of quasiparticles in the wire

Electrostatic force spectroscopy revealing the degree of reduction of individual graphene oxide sheets

• Yue Shen,
• Ying Wang,
• Yuan Zhou,
• Chunxi Hai,
• Jun Hu and
• Yi Zhang

Beilstein J. Nanotechnol. 2018, 9, 1146–1155, doi:10.3762/bjnano.9.106

• electrically induced reduction or oxidation may affect the degree of reduction of rGO sheets [17]. Scanning polarization force microscopy (SPFM), also called dielectric force microscopy, was developed firstly by Hu et al. in 1995 [18][19] to measure the dielectric properties of soft or weakly bound materials

• information (blue arrows marked in Figure 1i,k), indicating the contributions from the polarization force (dielectric properties) and the van der Waals force (topography) between the tip and sample. As we can see in the Figure 1l,m,n, the apparent height of samples 1 and 5 are 19.3 nm (Figure 1n) and 6.9 nm

• cantilever (Figure 3a). Because of polarization, opposing charges are induced at the vicinity of the sample surface, causing an attractive force between the tip and the sample, which leads to a phase shift of the cantilever. In the absence of electrical forces, the cantilever has a resonant frequency, f0

Semi-automatic spray pyrolysis deposition of thin, transparent, titania films as blocking layers for dye-sensitized and perovskite solar cells

• Hana Krýsová,
• Josef Krýsa and
• Ladislav Kavan

Beilstein J. Nanotechnol. 2018, 9, 1135–1145, doi:10.3762/bjnano.9.105

• photocurrent is very similar (around −0.3 V) on both our FTO supports and for various layer thicknesses. There is very small slope of the photocurrent/potential curve around the photocurrent onset and then an almost linear increase of the photocurrent. A similar shape in the polarization curve was observed

P3HT:PCBM blend films phase diagram on the base of variable-temperature spectroscopic ellipsometry

• Barbara Hajduk,
• Henryk Bednarski,
• Bożena Jarząbek,
• Henryk Janeczek and
• Paweł Nitschke

Beilstein J. Nanotechnol. 2018, 9, 1108–1115, doi:10.3762/bjnano.9.102

• polarization of reflected light. The change of light polarization is described by ellipsometric angles Ψ and Δ. Typically, ellipsometric investigations allow one to determine optical parameters, i.e., the refractive index n and the extinction coefficient k, or equivalently the complex dielectric function ε

Theoretical study of strain-dependent optical absorption in a doped self-assembled InAs/InGaAs/GaAs/AlGaAs quantum dot

• Tarek A. Ameen,
• Hesameddin Ilatikhameneh,
• Archana Tankasala,
• Yuling Hsueh,
• James Charles,
• Jim Fonseca,
• Michael Povolotskyi,
• Jun Oh Kim,
• Sanjay Krishna,
• Monica S. Allen,
• Jeffery W. Allen,
• Rajib Rahman and
• Gerhard Klimeck

Beilstein J. Nanotechnol. 2018, 9, 1075–1084, doi:10.3762/bjnano.9.99

• initial and final states, ń is the refractive index of the material, c is the speed of light in free space, ε0 is the free space permittivity, is the polarization of the incident light, and is the first-order dipole moment that is given by , where q is the electron charge. For transitions between bound

Electro-optical interfacial effects on a graphene/π-conjugated organic semiconductor hybrid system

• Karolline A. S. Araujo,
• Luiz A. Cury,
• Matheus J. S. Matos,
• Thales F. D. Fernandes,
• Luiz G. Cançado and
• Bernardo R. A. Neves

Beilstein J. Nanotechnol. 2018, 9, 963–974, doi:10.3762/bjnano.9.90

• other words, the same region of the RA monolayer and graphite substrate (blue dashed line in Figure 4a) was probed in the entire image. The EFM experiment was carried out at a fixed lift height (50 nm) above the sample surface while the polarization bias Vtip was varied at finite time intervals, and a

• resulting from permanent polarization or free charges on the surface [34]. In a simpler form, Equation 1 can be rewritten as According to Equation 1 and Equation 2, and since all EFM experiments were performed using the same cantilever and at a fixed lift height (fixed capacitance geometry), ∆ω in each

• region of the image is proportional to the dielectric constant of the material underneath the EFM tip, surface potential differences and to any accumulated charges/permanent polarization at the surface [34]. Equation 2 was used to fit all experimental data in Figure 4c–e (blue or brown solid lines in

Cyclodextrin inhibits zinc corrosion by destabilizing point defect formation in the oxide layer

• Abdulrahman Altin,
• Maciej Krzywiecki,
• Adnan Sarfraz,
• Cigdem Toparli,
• Claudius Laska,
• Philipp Kerger,
• Aleksandar Zeradjanin,
• Karl J. J. Mayrhofer,
• Michael Rohwerder and
• Andreas Erbe

Beilstein J. Nanotechnol. 2018, 9, 936–944, doi:10.3762/bjnano.9.86

• , negative charge must be accumulated, either by electron accumulation or by molecular polarization. The latter is more likely, as the amount of free charge carriers in a molecular insulator such as β-CD is expected to be rather low. As the O 1s peak of β-CD is most affected by the charge dislocation, it is

• , and the nature of ZnO, however, electrons are more likely to be the dominating species. In the case of a thick oxide layer, generation of a large polarization at the interface is a further possibility. No evidence exists here for such a polarization, and it is unlikely for the investigated case with a

• thin oxide. A band bending of ca. 0.1 eV is usually observed in oxides at interfaces and also in air [39]. During corrosion processes, electrode polarization lifts the band bending to the active corrosion potential [39]. The consequence of the energy level bending makes the ZnO less an n-type

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

• dielectric properties of nanomaterials, such as electrostatic force microscopy [16][17][18][19], scanning polarization force microscopy (SPFM) [20][21][22][23], local dielectric spectroscopy [24][25][26], and nanoscale capacitance microscopy [27][28][29]. Most of the proposed techniques are based on long

• , Fadh, will increase due to sample polarization (Figure 1b), which is positively correlated to its dielectric constant. Therefore, adhesion force mapping under a biased AFM tip can be expected to characterize the local dielectric property distribution. An example of adhesion force mapping with a biased

• substrate. This result indicates the increase in the adhesion force when the AFM tip is biased is due to the greater degree of polarization of CRGO with respect to the mica substrate, rather than charge injection into the CRGO sheets [43]. In this case, the apparent height of the CRGO sheet under the biased

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

• -decyloxybenzoate and 4-cyano-4′-pentylbiphenyl with a molar ratio of 1:1. The mixture is in the smectic A phase in the temperature range of 32.5–47.0 °C and has positive dielectric anisotropy. BaTiO3 is a ferroelectric material with high spontaneous polarization (0.26 C·m−2 at room temperature) [16][17]. In our

• . Ferroelectric particles have a dipole moment due to residual polarization and in the absence of a field their dipole moments are oriented parallel to the LC molecules (polarization–director coupling [23]). When an electric field is applied, these dipoles rotate to oriente themselves in the direction of the

• Figure 3) is associated with a slowing of the ratio P/E when the polarization approaches saturation. According to the formula this leads to a decrease in the dielectric permittivity of the particles and the colloid as a whole. This is confirmed by similar measurements in the crystalline phase of the

Valley-selective directional emission from a transition-metal dichalcogenide monolayer mediated by a plasmonic nanoantenna

• Haitao Chen,
• Mingkai Liu,
• Lei Xu and
• Dragomir N. Neshev

Beilstein J. Nanotechnol. 2018, 9, 780–788, doi:10.3762/bjnano.9.71

• 10.3762/bjnano.9.71 Abstract Background: Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) with intrinsically crystal inversion-symmetry breaking have shown many advanced optical properties. In particular, the valley polarization in 2D TMDCs that can be addressed optically has inspired new

• polarization; Introduction The inversion-symmetry breaking and quantum confinement in monolayer TMDCs offer unprecedented opportunities to explore valley-based physics and applications [1][2][3]. The valley pseudospin is associated with the degenerate energy extrema in momentum space [3]. In monolayer TMDCs

• [6][7][8][9][10]. In particular, monolayer TMDCs with direct bandgap at the K and K′ points [11] make it possible to control the valley degree freedom entirely optically. Optical pumping of excitons of a specific valley polarization has been demonstrated by polarization-resolved photoluminescence (PL

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

• energy cut-off of 400 eV was used and all ions were fully relaxed using a conjugate gradient scheme until the forces were less than 0.01 eV/Å. In the geometry optimizations for the molecule and the surface models the Brillouin zone was sampled at the Γ point only. Spin polarization was considered for all

Mechanistic insights into plasmonic photocatalysts in utilizing visible light

• Kah Hon Leong,
• Azrina Abd Aziz,
• Lan Ching Sim,
• Pichiah Saravanan,
• Min Jang and
• Detlef Bahnemann

Beilstein J. Nanotechnol. 2018, 9, 628–648, doi:10.3762/bjnano.9.59

• the visible spectrum was promoted through LSPR and is very well ascribed to the electric polarization effect. Moreover, LSPR also speeds up the electron movement from the photoexcited noble metal to the semiconductor [5]. The morphology, interparticle interactions and the local dielectric environment

High-contrast and reversible scattering switching via hybrid metal-dielectric metasurfaces

• Jonathan Ward,
• Khosro Zangeneh Kamali,
• Lei Xu,
• Guoquan Zhang,
• Andrey E. Miroshnichenko and
• Mohsen Rahmani

Beilstein J. Nanotechnol. 2018, 9, 460–467, doi:10.3762/bjnano.9.44

• ; Introduction Metasurfaces are thin and flat surfaces that are created using subwavelength optical antennas with various optical properties patterned at interfaces [1][2], enabling control over the polarization, phase, amplitude, and dispersion of light. Metasurfaces are growing in popularity as their optical

• properties can be adapted to a diverse set of applications along the electromagnetic spectrum [3] including dispersion engineering [4], polarization manipulation [5][6], pulse shaping [7], sensing [8][9] and tuning [10]. The first generation of metasurfaces mostly consisted of plasmonic nanostructures [11

• , respectively. The polarization of the incident beam is along y direction (along the gold bar lengths). A grating resonance in the spectrum occurs around 1235 nm at the grating diffraction edge (λ0 = n × D = 1.45 × 850 nm = 1232.5 nm) due to the constructive diffractive feedback among neighbouring antennas

Engineering of oriented carbon nanotubes in composite materials

• Razieh Beigmoradi,
• Abdolreza Samimi and
• Davod Mohebbi-Kalhori

Beilstein J. Nanotechnol. 2018, 9, 415–435, doi:10.3762/bjnano.9.41

• hard, solid or powder, biological, and organic or inorganic surfaces. This device can measure geometric morphology, adhesion distribution, friction, surface impurities, texture, elasticity, magnetism, chemical bonding forces, distribution of electric charges and electric polarization in different parts

• mode (G-band), disorder-induced mode (D-band), and other Raman features, determining the physical properties of the material. The G-band intensity as a function of the angle of polarization for individual CNTs can be related to their arrangement so that the G-band intensity of well-aligned CNT bulk

• materials should be higher than that of less-aligned CNTs. Figure 22 shows field emission (FE)-SEM micrographs of two CNT samples with random and aligned orientation and their polarized Raman spectra at 0° and 90° (0° related to the polarization direction of the laser light where it is parallel to the CNT

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

• ], the polarization field around a spherical cavity inside a dielectric medium is proportional to the applied field, so: Inside an anisotropic dielectric (the liquid crystal) the spherical cavity changes into an ellipsoid with the semi-axes and , where b is the cavity radius, is the parallel

• permittivity, is the perpendicular permittivity. In this case H becomes: where d(z) the depolarization coefficient, which for an ellipsoid with almost spherical shape (horizontal axis equal b = R and vertical axis a = R + 0.0005R) is If a quantum dot is placed inside this cavity, another polarization field

• was checked by using polarization microscopy. The mass concentration was 0.89%, which led to a volumetric fraction of 1.16% (the QD density is 0.87 g/cm3 and the density of 5CB is 1.02 g/cm3). The mixture was used to fill a 15 μm thick planar aligned cell from Instek, which was mounted in a holder

Design of polar self-assembling lactic acid derivatives possessing submicrometre helical pitch

• Alexej Bubnov,
• Cyril Vacek,
• Michał Czerwiński,
• Terezia Vojtylová,
• Wiktor Piecek and
• Věra Hamplová

Beilstein J. Nanotechnol. 2018, 9, 333–341, doi:10.3762/bjnano.9.33

• easily reachable by applying of a low frequency a.c. electric field. Spontaneous quantities The temperature dependences of the spontaneous polarization Ps and of the tilt angle θs (angle of (in-layer) molecular director with respect to the smectic layer normal) are shown in Figure 2a,b, respectively. The

• values of the spontaneous polarization Ps do not reveal any tendency to saturate on cooling. While comparing the homologues with the same length of non-chiral terminal chain, the Ps as well as θs values were found to slightly decrease with the increasing length of the alkyl chain at the chiral carbon

• ) for KL3/4 (a) and KL 4/5 (b). Vertical arrows indicate the peaks corresponding to phase transitions. Temperature dependencies of spontaneous polarization Ps, (a) and tilt angle of molecules θs, measured optically (b) for KL 3/4 (black rectangle), KL 3/5 (red circle), KL 4/4 (green triangle), KL 4/5