An advanced structural characterization of templated meso-macroporous carbon monoliths by small- and wide-angle scattering techniques

• Felix M. Badaczewski,
• Marc O. Loeh,
• Torben Pfaff,
• Dirk Wallacher,
• Daniel Clemens and
• Bernd M. Smarsly

Beilstein J. Nanotechnol. 2020, 11, 310–322, doi:10.3762/bjnano.11.23

• carbon materials. The disorder-induced D band arises from breathing vibrations of carbon rings and the G band resulting from carbon-chain vibrations prove the sp2-hybridized turbostratic microstructure. The G′ band is an overtone, where two phonons are involved. It scales with the number of layers in a

Variation of the photoluminescence spectrum of InAs/GaAs heterostructures grown by ion-beam deposition

• Alexander S. Pashchenko,
• Leonid S. Lunin,
• Eleonora M. Danilina and
• Sergei N. Chebotarev

Beilstein J. Nanotechnol. 2018, 9, 2794–2801, doi:10.3762/bjnano.9.261

• . In accordance with the selection rule, modes of longitudinal optical phonons (LO) and longitudinal acoustic phonons (LA) are allowed in the heterointerfaces. The Raman spectroscopy results are shown in Figure 3b. In addition to the allowed modes, forbidden transverse optical (TO) modes for optical

• phonons of bulk-like GaAs (268 cm−1) and GaBi (182 cm−1) are also observed. This indicates a change in the selection rule under Raman scattering in the InAs/GaAs system caused by lattice strain during the incorporation of Bi into the GaAs matrix. In the spectra we can clearly see the longitudinal modes of

• optical phonons of bulk GaAs (LO) at 283 cm−1, InAs QDs (LO) at 248 cm−1 and GaBi at 235 cm−1. Effects not detectable in the Raman spectrum of the InAs/GaAs heterostructure appear in the spectra of InAs/GaAs1−xBix samples in the interval of 150–250 cm−1. An increase in xBi is accompanied by the Raman

Nanoantenna structures for the detection of phonons in nanocrystals

• Alexander G. Milekhin,
• Sergei A. Kuznetsov,
• Ilya A. Milekhin,
• Larisa L. Sveshnikova,
• Tatyana A. Duda,
• Ekaterina E. Rodyakina,
• Alexander V. Latyshev,
• Volodymyr M. Dzhagan and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2018, 9, 2646–2656, doi:10.3762/bjnano.9.246

• (SEIRA) by optical phonons of semiconductor nanocrystals (NCs) deposited on the arrays. The arrays of nano- and microantennas fabricated with nano- and photolithography reveal infrared-active LSPR modes of energy ranging from the mid to far-infrared that allow the IR response from very low concentrations

• transverse optical phonons are activated in the infrared spectra. Keywords: localized surface plasmon resonance; metal nanoclusters; nanoantenna; phonons; semiconductor nanocrystals; surface-enhanced infrared absorption; Introduction Surface-enhanced infrared absorption (SEIRA) by organic species placed on

• SEIRA by optical phonons in semiconductor NCs [23]. The electromagnetic field distribution around the linear antennas was calculated using three-dimensional electrodynamics simulations, where the maximal SEIRA enhancement was realized for an array period of about 15 μm when the energy of a diffraction

Combined scanning probe electronic and thermal characterization of an indium arsenide nanowire

• Tino Wagner,
• Fabian Menges,
• Heike Riel,
• Bernd Gotsmann and
• Andreas Stemmer

Beilstein J. Nanotechnol. 2018, 9, 129–136, doi:10.3762/bjnano.9.15

• . Keywords: contact resistance; Kelvin probe force microscopy (KFM); nanowire; scanning thermal microscopy (SThM); self-heating; Introduction Electronic and thermal properties of nanoscale devices are innately coupled. The charge carriers in most conductors release energy by scattering at defects or phonons

Growth model and structure evolution of Ag layers deposited on Ge films

• Arkadiusz Ciesielski,
• Lukasz Skowronski,
• Ewa Górecka,
• Jakub Kierdaszuk and
• Tomasz Szoplik

Beilstein J. Nanotechnol. 2018, 9, 66–76, doi:10.3762/bjnano.9.9

• optical transmission, but the Raman spectrum barely changes. Due to germanium atoms distributed at the silver grain boundaries, which would no longer form Ge–Ge bonds (as it was in the case of a layer of Ge), and thus no longer conduct phonons, the peaks at 150–300 cm−1 should decrease significantly, yet

Changes of the absorption cross section of Si nanocrystals with temperature and distance

• Michael Greben,
• Petro Khoroshyy,
• Sebastian Gutsch,
• Daniel Hiller,
• Margit Zacharias and
• Jan Valenta

Beilstein J. Nanotechnol. 2017, 8, 2315–2323, doi:10.3762/bjnano.8.231

• of the efficiency of energy transfer between confined NC layers. An exponential decrease of the ACS with decreasing temperature down to 120 K can be explained by smaller occupation number of phonons and expansion of the band gap of Si NCs at low temperatures. This study clearly shows that the ACS of

• -assisted transitions the occupation number of phonons is an exponential function [1] of temperature containing the Bose–Einstein statistical factor: where Ωph is the typical (average) phonon energy and kB is the Boltzmann constant. Second, with varying temperatures the band gap of a NC is shifting. This

• first term on the right-hand side of Equation 24 is governed by the occupation number of phonons while the second term represents a function of the difference between photon energy and the band gap. It is also clear from Equation 24 that the higher the energy of a photon, , the larger the expected ACS

Velocity dependence of sliding friction on a crystalline surface

• Christian Apostoli,
• Giovanni Giusti,
• Jacopo Ciccoianni,
• Gabriele Riva,
• Rosario Capozza,
• Rosalie Laure Woulaché,
• Andrea Vanossi,
• Emanuele Panizon and
• Nicola Manini

Beilstein J. Nanotechnol. 2017, 8, 2186–2199, doi:10.3762/bjnano.8.218

• nature we understand by means of a Fourier analysis of the excited phonon modes. By relating the phonon phase velocities with the slider velocity, we obtain an equation whose solutions predict which phonons are being excited by the slider moving at a given speed. Keywords: atomic-scale friction; contact

• ; dissipation; friction; nanotribology; phonons; velocity dependence; Introduction Friction affects a wide variety of phenomena spanning broad ranges of length and time scales. Due to its practical and technological relevance, the study of friction was addressed even long before physics became a science

• kinetic energy of a macroscopic ordered motion into the internal energy of disordered thermal phonons. Both standard basic models of nanotribology, namely the Prandtl–Tomlinson model [1][2][13] and the Frenkel–Kontorova model [13][15][16][17][18], implement dissipation through a phenomenological viscous

Adsorbate-driven cooling of carbene-based molecular junctions

• Giuseppe Foti and
• Héctor Vázquez

Beilstein J. Nanotechnol. 2017, 8, 2060–2068, doi:10.3762/bjnano.8.206

• ) approximation [34], which consists of calculating the electron–phonon coupling matrix M in just one point of the Brillouin zone (Γ) for both electrons and phonons. The dynamical region includes the molecule, the Au atoms forming electrode terminations and the adsorbate atoms. The position of the molecule, tip

• tunneling electrons and thus contribute to the cooling of the junction. They add up to a total rate Ra,λ. These emission and absorption processes have been described in detail elsewhere [5][6][29][36]. Finally, vibrations can also dissipate energy into bulk phonons. The steady state solution for the

• population of vibrational mode λ (excluding anharmonic coupling between vibrational modes) is [36][37][38]: where the coupling of vibrations to tunneling electrons and to bulk phonons are both taken into account. The parameter describes the damping of molecular vibrations with bulk phonons in the left (L

3D continuum phonon model for group-IV 2D materials

• Morten Willatzen,
• Lok C. Lew Yan Voon,
• Appala Naidu Gandi and
• Udo Schwingenschlögl

Beilstein J. Nanotechnol. 2017, 8, 1345–1356, doi:10.3762/bjnano.8.136

• , King Abdullah University of Science and Technology, Thuwal 23955-6900, Kingdom of Saudi Arabia 10.3762/bjnano.8.136 Abstract A general three-dimensional continuum model of phonons in two-dimensional materials is developed. Our first-principles derivation includes full consideration of the lattice

• anisotropy and flexural modes perpendicular to the layers and can thus be applied to any two-dimensional material. In this paper, we use the model to not only compare the phonon spectra among the group-IV materials but also to study whether these phonons differ from those of a compound material such as

• either failed to recognize it [8] or were unable to explain it [1]. An alternative model of lattice vibrations is a classical continuum model, which is expected to reproduce most accurately phonons with wavelengths longer than lattice separations, i.e., near k = 0. One of the earliest such models applied

Impact of contact resistance on the electrical properties of MoS₂ transistors at practical operating temperatures

• Filippo Giannazzo,
• Gabriele Fisichella,
• Aurora Piazza,
• Salvatore Di Franco,
• Giuseppe Greco,
• Simonpietro Agnello and
• Fabrizio Roccaforte

Beilstein J. Nanotechnol. 2017, 8, 254–263, doi:10.3762/bjnano.8.28

• Vth was also investigated. A decrease of μ proportional to 1/Tα with α = 1.4 ± 0.3 was found, indicating scattering by optical phonons as the main limiting mechanism for mobility above room temperature. The value of Vth showed a large negative shift (about 6 V) increasing the temperature from 298 to

• dependence of μ ≈ 1/Tα with α > 1 indicates that the main mechanism limiting the mobility of electrons in the multilayer MoS2 channel in this temperature range is scattering by optical phonons, as reported by other experimental and theoretical investigations [4]. Instead, electron mobility was found to be

• , showing a decrease of μ ≈ 1/Tα with α = 1.4 ± 0.3 (indicating scattering by optical phonons as the limiting mechanism), and a negative shift of Vth by about 6 V with increasing T. The role played by electron trapping at the MoS2/SiO2 interface to explain such a large Vth shift was discussed. Experimental

Obtaining and doping of InAs-QD/GaAs(001) nanostructures by ion beam sputtering

• Sergei N. Chebotarev,
• Alexander S. Pashchenko,
• Leonid S. Lunin,
• Elena N. Zhivotova,
• Georgy A. Erimeev and
• Marina L. Lunina

Beilstein J. Nanotechnol. 2017, 8, 12–20, doi:10.3762/bjnano.8.2

• peak at 295 cm−2 caused by scattering of LO phonons of the GaAs substrate under x(yz) polarization. The weak peak at 270 cm−2 corresponds to scattering of GaAs TO phonons. To the right, at 254 cm−2, there is a peak of Raman scattering of InAs QDs. Figure 6b shows Raman scattering spectra for samples

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

• between plasmonic excitations of gold nanoantennas and optical phonons in SiO2 leads to the appearance of new plasmon–phonon modes observed in the infrared transmission spectra the frequencies of which are well predicted by the simulations. Keywords: nanoantenna array; localised surface plasmon resonance

• ; plasmon–phonon interaction; phonons; SiO2; Introduction Plasmonic metamaterials remain the object of keen interest both in fundamental and applied research due to their unique optical properties including negative and zero refraction, focusing, filtering, polarization manipulation, etc. [1][2][3][4

• plasmon–phonon coupling are to be expected. Indeed, as it was is shown in [31], such a coupling may drastically increase (by a factor of 200) the scattering intensity in the near field of the metal (Pt) tip of an atomic force microscope at frequencies of the SiC surface optical (SO) phonons. The results

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

A terahertz-vibration to terahertz-radiation converter based on gold nanoobjects: a feasibility study

• Kamil Moldosanov and
• Andrei Postnikov

Beilstein J. Nanotechnol. 2016, 7, 983–989, doi:10.3762/bjnano.7.90

• the theoretical prerequisites for the effect within the quasiparticle approach. Results and Discussion The microwave photons are considered to be quasiparticles with the dispersion law Eph = c·pph (c is the speed of light); the longitudinal phonons would be quasiparticles with the dispersion law Evm

• different context [1]. It is essential for our analysis that the nanoobjects are much larger in one dimension than in the other two, hence having the shape of nanobars or closed thin nanorings. We start with some numerical estimates. The strongest “assistance” of longitudinal phonons to electron excitations

• . Figure 3 sets the geometry of GNBs (left panel) and GNRs (right panel), for the discussion that follows. In a GNB, the compression waves (longitudinal phonons with the momentum nvmq and the energy Evm = vL·nvm·q) propagate along its length. It will be argued below that the momentum of an excited electron

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

• consequence, intriguing nonlinear phenomena, such as hysteresis, switching, and negative differential conductance have been observed in molecular junctions. In conducting molecules, either the center of mass oscillations [9], or thermally induced acoustic phonons [10] can be the source of coupling between

• and is the displacement field of the vibrational modes of the quantum dot. In Equation 6, the operators create (annihilate) phonons with momentum q and frequency ωq,α in the lead α. The left and right phonon leads will be considered as thermostats in equilibrium at the temperatures TL and TR

• possibility of the interaction between the relevant vibrational mode of the molecule and the phonons in the leads. Indeed, if this mode is elastically coupled with a neighbour atom of the leads by a spring with constant k′, one gets for the dissipative contribution of the leads in the dynamics of the mode

Current-induced runaway vibrations in dehydrogenated graphene nanoribbons

• Rasmus Bjerregaard Christensen,
• Jing-Tao Lü,
• Per Hedegård and
• Mads Brandbyge

Beilstein J. Nanotechnol. 2016, 7, 68–74, doi:10.3762/bjnano.7.8

• due to the nonequilibrium for lower voltage than where run-away instability occurs [29]. This asymmetry is intrinsically linked to momentum transfer from electrons to phonons and thus to the nonconservative current-induced forces (“electron wind”) [30]. As we mentioned before, the reason we choose

• motion of the two carbon atoms in each dimer only couples weakly to the motion of neighbouring dimers and to the phonons in the leads. This high-energy mode is shifted out of the entire phonon bandstructure. Meanwhile, the flowing electrical current passing through these dimers introduce a small bias

• (dotted lines) akin to the experimental conductance [5]. The introduction of the defects results mainly in a potential shift, but besides this does not impact the transmission dramatically, as seen in Figure 1b (solid lines). In order to characterize the phonons we show the phononic transmission in Figure

Controlled graphene oxide assembly on silver nanocube monolayers for SERS detection: dependence on nanocube packing procedure

• Martina Banchelli,
• Bruno Tiribilli,
• Roberto Pini,
• Luigi Dei,
• Paolo Matteini and
• Gabriella Caminati

Beilstein J. Nanotechnol. 2016, 7, 9–21, doi:10.3762/bjnano.7.2

• characteristic GO bands centred at 1601 cm−1 (G band) and at 1365 cm−1 (D band), and corresponding to the tangential stretching mode of the E2g phonon of sp2 atoms and to the breathing mode of κ-point phonons [59], respectively, dominate the Raman shift region between 1200 and 1700 cm−1 of the hybrid substrates

Probing the local environment of a single OPE3 molecule using inelastic tunneling electron spectroscopy

• Riccardo Frisenda,
• Mickael L. Perrin and
• Herre S. J. van der Zant

Beilstein J. Nanotechnol. 2015, 6, 2477–2484, doi:10.3762/bjnano.6.257

• , and a phonon with the same energy is created. In the case of a small inelastic current, the vibrationally excited molecule then returns to its ground state typically before the excitation of a new vibration by a subsequent electron. The excess energy is converted to phonons in the electrodes and/or

Surface-enhanced Raman scattering by colloidal CdSe nanocrystal submonolayers fabricated by the Langmuir–Blodgett technique

• Alexander G. Milekhin,
• Larisa L. Sveshnikova,
• Tatyana A. Duda,
• Ekaterina E. Rodyakina,
• Volodymyr M. Dzhagan,
• Ovidiu D. Gordan,
• Sergey L. Veber,
• Cameliu Himcinschi,
• Alexander V. Latyshev and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2015, 6, 2388–2395, doi:10.3762/bjnano.6.245

• 10.3762/bjnano.6.245 Abstract We present the results of an investigation of surface-enhanced Raman scattering (SERS) by optical phonons in colloidal CdSe nanocrystals (NCs) homogeneously deposited on both arrays of Au nanoclusters and Au dimers using the Langmuir–Blodgett technique. The coverage of the

• deposited NCs was less than one monolayer, as determined by transmission and scanning electron microscopy. SERS by optical phonons in CdSe nanocrystals showed a significant enhancement that depends resonantly on the Au nanocluster and dimer size, and thus on the localized surface plasmon resonance (LSPR

• ; localized surface plasmon resonance; metal nanoclusters; phonons; surface-enhanced Raman spectroscopy; Introduction Since its observation in 1974 [1], surface-enhanced Raman scattering (SERS) has become a powerful technique for detecting and studying ultra-low quantities of organic and biological

Influence of wide band gap oxide substrates on the photoelectrochemical properties and structural disorder of CdS nanoparticles grown by the successive ionic layer adsorption and reaction (SILAR) method

• Mikalai V. Malashchonak,
• Alexander V. Mazanik,
• Olga V. Korolik,
• Еugene А. Streltsov and
• Anatoly I. Kulak

Beilstein J. Nanotechnol. 2015, 6, 2252–2262, doi:10.3762/bjnano.6.231

• /CdS, and In2O3/CdS heterostructures The Raman spectra of ZnO/CdS, TiO2/CdS, and In2O3/CdS films are shown in Figure 5. In the studied range of Raman shifts, the band at ≈300 cm−1 corresponded to scattering by CdS longitudinal optical (LO) phonons [20] and also two of its overtones (≈600 and ≈900 cm−1

• factors: phonon confinement leading to relaxation of the k = 0 selection rule for single-phonon scattering (k is a phonon wavevector) and an asymmetric low-energy LO band broadening [22]; scattering by disorder-activated zone-edge (DAZE) phonons [23]; or scattering by surface optical (SO) phonons [24]. As

• is known, the influence of phonon confinement on the line shape in Raman spectra increases with dispersion, ω(k), of optical phonons. For CdS, where the LO phonon frequency ω slightly depends on the wavevector, the impact of phonon confinement on the shape of spectral lines becomes significant only

A single-source precursor route to anisotropic halogen-doped zinc oxide particles as a promising candidate for new transparent conducting oxide materials

• Daniela Lehr,
• Markus R. Wagner,
• Johanna Flock,
• Julian S. Reparaz,
• Clivia M. Sotomayor Torres,
• Alexander Klaiber,
• Thomas Dekorsy and
• Sebastian Polarz

Beilstein J. Nanotechnol. 2015, 6, 2161–2172, doi:10.3762/bjnano.6.222

• longitudinal optical phonon–plasmon coupling and describes the interaction of collective oscillating free carriers (plasmons) with LO phonons [80]. Consequently, the concentration of free carriers increases with Cl doping. The dielectric properties of thin ZnO1−xClx pellets were investigated with impedance

Nonconservative current-driven dynamics: beyond the nanoscale

• Brian Cunningham,
• Tchavdar N. Todorov and
• Daniel Dundas

Beilstein J. Nanotechnol. 2015, 6, 2140–2147, doi:10.3762/bjnano.6.219

• refer to it generically as the waterwheel effect. Here the connection between the waterwheel effect and the stimulated directional emission of phonons propagating along the electron flow is discussed in an intuitive manner. Nonadiabatic molecular dynamics show that waterwheel modes self-regulate by

• winds generate forward-travelling ripples on a lake, or the uncompensated stimulated emission of directional phonons [12][15]. However, this process hinges on momentum conservation, and for waves, this information requires a sufficiently long-ranged physical property. For atomic motion under current

• for longitudinal phonons in a chain with 200 mobile atoms of mass M = 10 amu. The 200 eigenvalues {kj} of the 200 × 200 dynamical response matrix give rise to 2 × 200 eigenfrequencies: positive and negative square roots of the eigenvalues divided by mass, ωj = . Each eigenvector of the dynamical

Thermoelectricity in molecular junctions with harmonic and anharmonic modes

• Bijay Kumar Agarwalla,
• Jian-Hua Jiang and
• Dvira Segal

Beilstein J. Nanotechnol. 2015, 6, 2129–2139, doi:10.3762/bjnano.6.218

• transport characteristics across the junction, mediated by molecular vibrational modes. Consideration of the phononic thermal conductance κph is particularly important for a reliable estimate of ZT, as the thermal conductance Σ should include contributions from both electrons and phonons. We now estimate

Simulation of thermal stress and buckling instability in Si/Ge and Ge/Si core/shell nanowires

• Suvankar Das,
• Amitava Moitra,
• Mishreyee Bhattacharya and
• Amlan Dutta

Beilstein J. Nanotechnol. 2015, 6, 1970–1977, doi:10.3762/bjnano.6.201

• composite system. In the same way, the presence of an interface modulates the state of phonons in these nanowires and the analytical estimation of the net thermal expansion by conventional thermo-mechanical theory becomes unfeasible. In view of these difficulties, atomistic simulations have been employed to

Large-voltage behavior of charge transport characteristics in nanosystems with weak electron–vibration coupling

• Tomáš Novotný and
• Wolfgang Belzig

Beilstein J. Nanotechnol. 2015, 6, 1853–1859, doi:10.3762/bjnano.6.188

• coupling regime only but which would use simplified (semi)analytical formulas for the IETS features with non-equilibrated phonons. It turns out that there are two methods yielding inconsistent results, namely a paper by Urban et al. [18] and a study by us [19] for the inelastic current noise extended by