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

• (thickness) by approx. 100 nm (length of GNB, or along the GNR). This detailed prediction is open to experimental verification. An impact is expected onto further studies of interplay between atomic vibrations and electromagnetic waves in nanoobjects. Keywords: longitudinal acoustic phonon; microwave photon

• transform into radiative energy of the THz range? It turns out that in metal nanoparticles, the LAVMs can be converted into electromagnetic waves with the help of Fermi electrons. Our idea consists of the simultaneous excitation of these latter by exposing them to a THz field of longitudinal phonon and

• /momentum conservation laws. The latter are grasped by the scheme in Figure 1 where an excitation of a Fermi electron “upwards” through mel quantization steps ΔEel is brought about by a joint absorption of a RF quantum and an appropriate longitudinal phonon. Subsequently the excited electron relaxes to the

Thermo-voltage measurements of atomic contacts at low temperature

• Ayelet Ofarim,
• Bastian Kopp,
• Thomas Möller,
• León Martin,
• Johannes Boneberg,
• Paul Leiderer and
• Elke Scheer

Beilstein J. Nanotechnol. 2016, 7, 767–775, doi:10.3762/bjnano.7.68

• temperature dependence of the resistivity should be dominated by electron-phonon scattering, we obtained an effective thickness of 63 nm. This reduction can be caused by the formation of a dead layer or by increased roughness due to the etching process. The complete length of the sensor leads including the

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

• vibrational modes and the electronic degrees of freedom affects the thermoelectric properties within the linear response regime finding out that the phonon thermal conductance provides an important contribution to the figure of merit at room temperature. Our work has been stimulated by recent experimental

• the range of validity of the approach, focusing first on the case of zero bias voltage at any temperature, then on the case of zero temperature at finite bias voltages. The thermoelectric properties have then been analyzed within the linear response regime focusing on the phonon thermal contribution

• 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

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

• circular “water-wheel” motion, either in real space [10] or in mode space. Another requirement is that these modes have little damping due to the coupling to the phonon reservoir. Unfortunately, there has not been a clear experimental setup where these new theoretical findings can be put to a test proving

• describe the coupling to the phonon reservoirs outside device, while the self-energy describes the coupling to the electrons. In equilibrium, this result has been obtained by, i.e., Head-Gordon and Tully [21]. In principle we may apply the SGLE including the non-linear part of F [22], but here we will

• ), given by, Here, Aα/β is the density of scattering states incoming from left and right electrodes (indices α and β), while M describes the electron–phonon couplings (k and l phonon indices). One can loosely think of the motion of phonon k excites an electron–hole pair of energy which is absorbed by

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

Calculations of helium separation via uniform pores of stanene-based membranes

• Guoping Gao,
• Yan Jiao,
• Yalong Jiao,
• Fengxian Ma,
• Liangzhi Kou and
• Aijun Du

Beilstein J. Nanotechnol. 2015, 6, 2470–2476, doi:10.3762/bjnano.6.256

• , SnH, and SnF lattices under different strains. Supporting Information Supporting Information File 128: The phonon dispersion spectrum and stress–strain curves of Sn, SnH and SnF lattices. Acknowledgements We acknowledge generous grants of high-performance computer time from the computing facility at

Vibration-mediated Kondo transport in molecular junctions: conductance evolution during mechanical stretching

• David Rakhmilevitch and
• Oren Tal

Beilstein J. Nanotechnol. 2015, 6, 2417–2422, doi:10.3762/bjnano.6.249

• ; electron–phonon interactions; Kondo effect; molecular junctions; vibrations; Introduction Molecular junctions are an attractive test-bed for electronic effects such as Kondo physics [1][2][3][4][5] and electron–vibration interaction [6][7][8][9][10]. These junctions are composed of individual molecules

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

• . From one side, colloidal CdSe NCs are already used in commercial applications [31]. The information on the crystal structure of the NCs, their size, shape, and mechanical strain (which can be derived from the frequencies of the Raman phonon modes as seen in SERS spectra) is crucial for device

• previously observed for several CdSe-based NCs, including pure CdSe and core–shell CdSe/CdZnS NCs deposited on Au or Ag substrates of various morphology [20][21][22][23]. Resonant SERS enables the observation of LO phonon modes of the CdSe core in a monolayer of core–shell CdSe/ZnS NCs deposited on

• commercially available SERS substrates [20]. However, the usage of conventional SERS conditions provides a SERS enhancement that is insufficient for investigation of an individual nanostructure. Very recently, it was demonstrated that the phonon spectrum of individual CdSe nanoplatelets can be probed by SERS

Evidence for non-conservative current-induced forces in the breaking of Au and Pt atomic chains

• Carlos Sabater,
• Carlos Untiedt and
• Jan M. van Ruitenbeek

Beilstein J. Nanotechnol. 2015, 6, 2338–2344, doi:10.3762/bjnano.6.241

• chains, or the investigation of other atomic scale systems that permit a higher degree of control. On the side of theory the effects of phonon decay have not been included. Qualitative estimates of the effect of phonon decay suggest that they can have a profound influence on the final size of the non

Correction: 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, 2330–2331, doi:10.3762/bjnano.6.239

• lines); An infrared-active phonon at about 2 THz is scaling in intensity with increasing Cl concentration.

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

• occurrence of the quantum confinement effect, demonstrating the most rapid weakening with the increase of N in ZnO/CdS heterostructures. The structural disorder of CdS nanoparticles was characterized by the Urbach energy (EU), spectral width of the CdS longitudinal optical (LO) phonon band and the relative

• intensity of the surface optical (SO) phonon band in the Raman spectra. Maximal values of EU (100–120 meV) correspond to СdS nanoparticles on a In2O3 surface, correlating with the fact that the CdS LO band spectral width and intensity ratio for the CdS SO and LO bands are maximal for In2O3/CdS films. A

• , Raman spectra are determined by both phonon and electron spectra of the system under study, electron–phonon coupling, material defectiveness, and elastic stresses, providing therefore valuable information about the NP properties. Nevertheless, to the best of our knowledge, there are no thorough studies

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

• is dominated by a transition at 3.32 eV. This zero-phonon line is repeated by longitudinal optical phonon replicas with an energy spacing of 72 meV. The high intensity of the phonon replicas is characteristic for a strong electron–phonon coupling as it is typically observed for donor acceptor pairs

• , is assigned to a donor-bound exciton recombination at a structural defect [74]. The spectra of the 2.5% sample are dominated by the D0X shallow donor-bound exciton recombination with one phonon replica of the D0X visible. The low-temperature PL spectrum of the highest doped Cl@ZnO sample resembles

• 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

• can ruin the degeneracies) is small in these quasi-ballistic systems. Finally, electrons couple strongly to extended phonon modes with the wavevectors needed for momentum conservation under backscattering [14]. Simulations under current indeed show NC dynamics in long atomic wires on a grand scale [13

• spontaneous phonon emission and Joule heating [20]. By contrast with the Landauer method above, the dynamical simulations accommodate departures from steady-state conditions and allow the current to respond to changes in the vibrational amplitudes. To compare the two methods we will further perform a short

• -time Fourier transform on the ion trajectories (t) from the dynamical simulations and examine the evolution of the energy distribution across the phonon band. The Fourier transform uses a Blackman window, effectively suppressing data outside a particular time interval, while ensuring the data remains

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

• coefficients reveal on molecular junctions? Specifically, can they expose the underlying electron–phonon interactions and the characteristics of the vibrational modes participating in the process? Focusing on the challenge of efficient thermoelectric systems, how should we tune molecular parameters to improve

• thermoelectric transport have been developed, e.g., in [50][51][52][53], accounting for many-body effects in a phenomenological manner. Only few studies had considered this problem with explicit electron–phonon interactions, based on the Anderson–Holstein model [54] or Fermi Golden rule expressions [14]. In

• “vibrational instability”. This over-heating effect occurs when (electron-induced) vibrational excitation rates exceed relaxation rates. To cure this physical problem, we allow the particular vibrational mode of frequency ω0 to relax its excess energy to a secondary phonon bath of temperature Tph. This can be

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

• for next generation transistor devices. The radial heterostructure offers the advantage of control of the band gap and charge carrier mobility by tuning their size [5] and selecting suitable impurity doping scheme [3][6]. In addition, they exhibit significantly suppressed phonon thermal conductivity

• motion makes the real temperature, T, different from the classical temperature, TMD, as measured from the simulations. Wang et al. [30] proposed an approximate relation for scaling between the classical and real temperatures based on the phonon frequencies in the solid. Accordingly, this procedure has

Simple and efficient way of speeding up transmission calculations with k-point sampling

• Jesper Toft Falkenberg and
• Mads Brandbyge

Beilstein J. Nanotechnol. 2015, 6, 1603–1608, doi:10.3762/bjnano.6.164

• or phonon transport in the Landauer transport picture. We suggest a simple and computationally “cheap” post-processing scheme to interpolate transmission functions over k-points to get smooth well-converged average transmission functions. This is relevant for data obtained using typical “expensive

• illustrated the method using electron transport through graphene nano-structures and k-point averaging of transmission functions. However, the method is generally applicable also to phonon transport and to other functions such as density of states or other types of interpolation parameters such as

Possibilities and limitations of advanced transmission electron microscopy for carbon-based nanomaterials

• Xiaoxing Ke,
• Carla Bittencourt and
• Gustaaf Van Tendeloo

Beilstein J. Nanotechnol. 2015, 6, 1541–1557, doi:10.3762/bjnano.6.158

• , i.e., EDX), all uniquely characterize the studied materials. Chemical compositions, electron fine structures, even the phonon vibrations [31] produced by electron–matter interactions can be acquired, which is quite exciting for a detailed study. Therefore, electron beams are more than an illumination

• electronic scattering and phonon scattering are very likely to be disturbed at the boundary. The fundamental studies on the atomic structure of graphene have a significant impact on the large-scale applications of graphene. Graphene synthesized through chemical vapor deposition (CVD) often exhibits a

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

• hand, the manganite oxide perovskites are strongly correlated electron systems that exhibit a strong electron–phonon interaction. This leads to the formation of small polarons [21]. The polaron-like character of the quasi-particles in perovskite oxides provides at least two exciting issues related to

• electron–phonon interaction across the interface. Under a large electric field, the polaron may even dissociate as indicated by polaron simulations of polymer junctions [33]. On the other hand, the concept of the electrochemical equilibrium at the interface naturally takes into account the spatial

• renormalization of the bandwidth by the electron–phonon interaction further reduces the bandwidth to a few meV [35]. This small bandwidth has strong impact on the matching of electronic states at the interface. Even after establishment of electrochemical equilibrium (which may be hindered by small charge transfer

Electron and heat transport in porphyrin-based single-molecule transistors with electro-burnt graphene electrodes

• Hatef Sadeghi,
• Sara Sangtarash and
• Colin J. Lambert

Beilstein J. Nanotechnol. 2015, 6, 1413–1420, doi:10.3762/bjnano.6.146

• small as 10 meV increases the thermopower to 475 μV/K. In contrast, the electronic thermal conductance of the device is quite low and does not change significantly with the small variation of the Fermi energy. The thermoelectric figure-of-merit could be high in this device provided the phonon

Enhancing the thermoelectric figure of merit in engineered graphene nanoribbons

• Hatef Sadeghi,
• Sara Sangtarash and
• Colin J. Lambert

Beilstein J. Nanotechnol. 2015, 6, 1176–1182, doi:10.3762/bjnano.6.119

• for this are changes in the phonon density of states, an increased phonon-boundary scattering and the dispersion of the nanostructures in low dimensional semiconductors [2][4][5][6]. The efficiency of thermoelectric materials and devices is determined by their thermoelectric figure of merit (ZT = S2GT

• greater than unity is challenging. The most common material used in thermoelectric applications is bismuth and its alloys, which are toxic, expensive and of limited availability. To improve ZT in new materials, one promising route has been to take advantage of the reduced phonon thermal conductance (κpl

• graphene [20]. This means that 2D graphene and its multilayer counterparts are useful for thermal management applications [21]. The high thermal conductivity of the graphene is mainly due to the high phonon contribution to heat transport. Therefore, for thermoelectricity applications, one needs to engineer

Electronic interaction in composites of a conjugated polymer and carbon nanotubes: first-principles calculation and photophysical approaches

• Florian Massuyeau,
• Jany Wéry,
• Jean-Luc Duvail,
• Serge Lefrant,
• Abu Yaya,
• Chris Ewels and
• Eric Faulques

Beilstein J. Nanotechnol. 2015, 6, 1138–1144, doi:10.3762/bjnano.6.115

• without hopping to the SWNTs. This implies that they survive longer with a slower time constant τ2. Therefore, we suggest associating the fast decay component to the PL of PPV, which is quenched by a non-radiative transfer of energy to the polymer network via phonon emission. This process results from the

• approach assumes that the radiative and non-radiative lifetimes τr, τnr can be expressed as a function of the PL quantum yield Q, , . τnr accounts for phonon emission, intersystem crossing to triplet states, trapping at chemical defects and exciton migration/dissociation. For standard PPV (x = 0%) we find

Effects of swift heavy ion irradiation on structural, optical and photocatalytic properties of ZnO–CuO nanocomposites prepared by carbothermal evaporation method

• Sini Kuriakose,
• D. K. Avasthi and
• Satyabrata Mohapatra

Beilstein J. Nanotechnol. 2015, 6, 928–937, doi:10.3762/bjnano.6.96

• that wurtzite ZnO has an irreducible representation A1 + 2B1 + E1 + 2E2. Since the modes A1 and E1 are polar they exhibit two frequencies corresponding to the transverse optical (TO) and the longitudinal optical (LO) phonon modes. The non-polar E2 mode has two frequencies E2(high) originating from the

Combination of surface- and interference-enhanced Raman scattering by CuS nanocrystals on nanopatterned Au structures

• Alexander G. Milekhin,
• Nikolay A. Yeryukov,
• Larisa L. Sveshnikova,
• Tatyana A. Duda,
• Ekaterina E. Rodyakina,
• Victor A. Gridchin,
• Evgeniya S. Sheremet and
• Dietrich R. T. Zahn

Beilstein J. Nanotechnol. 2015, 6, 749–754, doi:10.3762/bjnano.6.77

• substrate reveal only features corresponding to crystalline Si. However, a new relatively strong peak occurs in the Raman spectrum of CuS NCs on Au nanocluster arrays at 474 cm−1. This feature is related to the optical phonon mode in CuS NCs and manifests the SERS effect. For CuS NCs deposited on a SiO2

• layer this phonon mode is also observed due to the IERS effect. Its intensity changes periodically with increasing SiO2 layer thickness for different laser excitation lines and is enhanced by a factor of about 30. CuS NCs formed on Au nanocluster arrays fabricated on IERS substrates combine the

• optical (SO) and LO phonon modes in a CdSe core and the transverse optical (TO) phonon mode in a ZnS shell of core–shell CdSe/ZnS NCs attached to the surface of a Au nanowire. The spectrum of optical and interface phonons was obtained from the analysis of SERS spectra of pure CdSe NCs, core–shell CdSe/CdS