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

• based on minimal model Hamiltonians are largely focused on the Anderson impurity dot model which consists a single molecular electronic orbital directly coupled to biased metal leads, as well as to a particular vibrational mode [1]. Since the same molecular orbital is assumed to extend both contacts

• thermopower, a linear response quantity, also referred to as the Seebeck coefficient, is utilized as an independent tool for probing the energetics of molecular junctions [17][18][19][20][21][22][23][24]. Experimental efforts identified orbital hybridization, contact-molecule energy coupling and geometry, and

Controlled switching of single-molecule junctions by mechanical motion of a phenyl ring

• Yuya Kitaguchi,
• Satoru Habuka,
• Hiroshi Okuyama,
• Shinichiro Hatta,
• Tetsuya Aruga,
• Thomas Frederiksen,
• Magnus Paulsson and
• Hiromu Ueba

Beilstein J. Nanotechnol. 2015, 6, 2088–2095, doi:10.3762/bjnano.6.213

• ascribed to a stronger hybridization with the substrate states as revealed by the increased projected density of states (PDOS) onto the chalcogen atom near EF (Figure 6b,d; more extended atomic orbitals of S than of O) as well as by the larger width of the lowest unoccupied molecular orbital (LUMO

Conductance through single biphenyl molecules: symmetric and asymmetric coupling to electrodes

• Karthiga Kanthasamy and
• Herbert Pfnür

Beilstein J. Nanotechnol. 2015, 6, 1690–1697, doi:10.3762/bjnano.6.171

• orbital with energy E0 governs electronic transmission, the transmission function is given by the Breit–Wigner formula, For the symmetric molecule, the coupling parameters to both sides are equal: Γ = Γ1 = Γ2. Using the single level model, Γ and E0 were varied in order to obtain a best fit to all measured

The eNanoMapper database for nanomaterial safety information

• Nina Jeliazkova,
• Charalampos Chomenidis,
• Philip Doganis,
• Bengt Fadeel,
• Roland Grafström,
• Barry Hardy,
• Janna Hastings,
• Markus Hegi,
• Vedrin Jeliazkov,
• Nikolay Kochev,
• Pekka Kohonen,
• Cristian R. Munteanu,
• Haralambos Sarimveis,
• Bart Smeets,
• Pantelis Sopasakis,
• Georgia Tsiliki,
• David Vorgrimmler and
• Egon Willighagen

Beilstein J. Nanotechnol. 2015, 6, 1609–1634, doi:10.3762/bjnano.6.165

Electrical properties and mechanical stability of anchoring groups for single-molecule electronics

• Riccardo Frisenda,
• Simge Tarkuç,
• Elena Galán,
• Mickael L. Perrin,
• Rienk Eelkema,
• Ferdinand C. Grozema and
• Herre S. J. van der Zant

Beilstein J. Nanotechnol. 2015, 6, 1558–1567, doi:10.3762/bjnano.6.159

• electrodes EF and the energy of the closest frontier orbital in the molecule ε0 = |EF−ε|, where ε is the energy of the molecular level. In the Landauer transport formalism [44], at zero temperature, the current is given by: where T(E) is the transmission, that in the single-level model is a Lorentzian peak

Transformations of PTCDA structures on rutile TiO₂ induced by thermal annealing and intermolecular forces

• Szymon Godlewski,
• Jakub S. Prauzner-Bechcicki,
• Thilo Glatzel,
• Ernst Meyer and
• Marek Szymoński

Beilstein J. Nanotechnol. 2015, 6, 1498–1507, doi:10.3762/bjnano.6.155

• outstanding oxygen rows. However, when a higher resolution is achieved the single molecule is imaged as a characteristic double lobe feature, as noted by a dashed circle in Figure 2b. This finding enables us to determine the molecule orientation on the surface, as the lowest unoccupied molecular orbital (LUMO

• ) should contribute mostly to the STM appearance when imaging of empty states is performed. The charge density contour of the PTCDA LUMO orbital comprises 14 lobes located symmetrically with respect to the longer molecular axis, where the orbital wave function changes its sign. As a result, the charge

Molecular materials – towards quantum properties

• Mario Ruben

Beilstein J. Nanotechnol. 2015, 6, 1485–1486, doi:10.3762/bjnano.6.153

• . In some of the proposed device materials, quantum information is carried by the spin and the orbital degree of freedom of the electron. The challenge consists in circumventing the strong coupling of the latter one with the environment in order to achieve the needed long coherence times to carry out

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

• rates), the electronic overlap of narrow bands can be very small. In other words, the orbital mismatch of the electronic states on both sides of the interface may strongly affect the charge transfer process. The width of the space charge region (SCR) at the junctions of conventional semiconductors can

Enhanced fullerene–Au(111) coupling in (2√3 × 2√3)R30° superstructures with intermolecular interactions

• Michael Paßens,
• Rainer Waser and
• Silvia Karthäuser

Beilstein J. Nanotechnol. 2015, 6, 1421–1431, doi:10.3762/bjnano.6.147

• , in case of fullerenes it is also possible to identify the orbital symmetry, whose appearance strongly depends on the rotational orientation of single C60, like shown in simulations of empty-state STM-images of free fullerenes [15]. Therefore, it was possible to identify this (√589 × √589)R14.5

• superstructures of C60 on Au(111) surfaces, we investigate in detail the orbital symmetry and thus, the rotational orientation and interface interactions of fullerenes in disordered and uniform (2√3 × 2√3)R30° superstructures. These structural investigations are complemented by conductance measurements sheding

• measured for a positive sample bias (Ubias > 1.0 V), when electrons are tunneling from the tip into the lowest unoccupied molecular orbital (LUMO) of C60. However, the apparent height difference between hex-vac and 6:6-top C60 depends strongly on the applied bias voltage and exhibits the steepest slope

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

• ][12][13][14][15][16] is the close match of their Fermi energy with the highest occupied molecular orbital (HOMO) or lowest unoccupied molecular orbital (LUMO) energy levels of organic molecules. Furthermore, in comparison to the more bulky metallic electrodes, graphene electrodes promote electrostatic

• electronic structure of the prophyrin molecule. Then we study the electro-burnt graphene electrodes and finally the two-terminal device in which the anchor groups of the porphyrin molecule bind to the graphene electrodes by p-orbital overlap. We then discuss the contribution of each part of the molecule to

• EBG electrode. The electrode is a 3 nm wide, zigzag, semi-infinite, graphene nanoribbon terminated by oxygen and connected to a half-ellipse-like structure as shown in Figure 3a. The molecular orbital levels in the Fermi energy, EF = 0 eV, indicate that the orbitals are mostly localized in the edges

High photocatalytic activity of V-doped SrTiO₃ porous nanofibers produced from a combined electrospinning and thermal diffusion process

• Panpan Jing,
• Wei Lan,
• Qing Su and
• Erqing Xie

Beilstein J. Nanotechnol. 2015, 6, 1281–1286, doi:10.3762/bjnano.6.132

• unoccupied conduction band (CB) are composed of the O 2p and Ti 3d-t2g states, respectively [15]. Due to the small contribution of Sr to the orbital characteristics of the conduction band, the energy difference between the O 2p and Ti 3d states mainly causes the band structure and insulation characteristic

Can molecular projected density of states (PDOS) be systematically used in electronic conductance analysis?

• Tonatiuh Rangel,
• Gian-Marco Rignanese and
• Valerio Olevano

Beilstein J. Nanotechnol. 2015, 6, 1247–1259, doi:10.3762/bjnano.6.128

• of the zero-bias conductance. A very common approach for providing such an interpretation proceeds as follows. A set of molecular orbitals (MOs) associated to the central molecule are identified and classified according to the energy levels (e.g., the highest occupied molecular orbital (HOMO), or the

• lowest unoccupied molecular orbital (LUMO), or the next LUMO (LUMO+1), etc.). Then, the total electronic density of states (DOS) is decomposed into the projected density of states (PDOS) associated with each different MO. Finally, by directly comparing the conductance profile, , with the various PDOS

• molecular orbital m is defined as where n runs over all the states of the central extended molecule with wavefunction and energy εn. In Equation 1, the Dirac delta function is usually replaced by a Gaussian function with a given broadening. As discussed above, is primarily determined by the electronic

Electrical characterization of single molecule and Langmuir–Blodgett monomolecular films of a pyridine-terminated oligo(phenylene-ethynylene) derivative

• Henrry M. Osorio,
• Santiago Martín,
• María Carmen López,
• Santiago Marqués-González,
• Simon J. Higgins,
• Richard J. Nichols,
• Paul J. Low and
• Pilar Cea

Beilstein J. Nanotechnol. 2015, 6, 1145–1157, doi:10.3762/bjnano.6.116

• efficient pyridyl–Au contacts. Previous contributions in the field have shown that the charge transport in molecular wires incorporating electron-withdrawing pyridyl-type anchoring groups is preferentially controlled by the lowest unoccupied molecular orbital (LUMO). That is, the pyridyl group decreases the

• frontier orbital energies and promotes electron transport by reducing the energy offset between the molecular LUMO and the Fermi level of electrodes [102][103][104]. In particular, DFT-based studies of 1 in single molecule junctions have shown that the total conductance is controlled by eigenchannels

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

• that these are ground state calculations and do not take into account the electron dynamics involved in exciton formation and separation, calculations that are unfortunately inaccessible with our available computing resources. The highest occupied molecular orbital (HOMO) and lowest occupied molecular

• orbital (LUMO) states for the (7,0) and (4,4) nanotubes in the presence of the triphenyl PPV oligomer are shown in Figure 3. It can be seen that in the presence of the (7,0) tube the system HOMO is primarily localized on the vinyl double bonds along the PPV backbone. Curvature in the PPV oligomer will

Charge carrier mobility and electronic properties of Al(Op)₃: impact of excimer formation

• Andrea Magri,
• Pascal Friederich,
• Bernhard Schäfer,
• Valeria Fattori,
• Xiangnan Sun,
• Timo Strunk,
• Velimir Meded,
• Luis E. Hueso,
• Wolfgang Wenzel and
• Mario Ruben

Beilstein J. Nanotechnol. 2015, 6, 1107–1115, doi:10.3762/bjnano.6.112

• = 5.54 eV and EA = 1.94 eV in environment. Additional charges in the system, which can be considered as SOMO+ and SOMO− orbital energies, lead to values of −6.47 eV for the oxidized state (hole) and −0.79 eV for the reduced state (electron). The self-consistently evaluated HOMO and LUMO levels in an Alq3

• and 5.55 ± 0.91 D for Alq3. The increase of the dipole moment of Al(Op)3 is much more dramatic, indicating a break in the intrinsic, vacuum symmetry, which is reflected in the orbital localization and is clearly observable in Figure 7b. As we treated the molecules in the matrix to be rigid, the

Superluminescence from an optically pumped molecular tunneling junction by injection of plasmon induced hot electrons

• Kai Braun,
• Xiao Wang,
• Andreas M. Kern,
• Hilmar Adler,
• Heiko Peisert,
• Thomas Chassé,
• Dai Zhang and
• Alfred J. Meixner

Beilstein J. Nanotechnol. 2015, 6, 1100–1106, doi:10.3762/bjnano.6.111

• emission intensity depends non-linearly on the optical pump power. The enhanced emission can be modelled by rate equations taking into account hole injection from the tip (anode) into the highest occupied orbital of the closest substrate-bound molecule (lower level) and radiative recombination with an

• substrate indeed confirm that the energetic distribution of the highest occupied molecular orbital (HOMO) with respect to the Fermi level of the Au substrate lies between −1.2 and −2.0 eV and the d-bands of Au lie below −2.0 eV (see Figure S6, Supporting Information File 1). These values are consistent with

Tunable magnetism on the lateral mesoscale by post-processing of Co/Pt heterostructures

• Oleksandr V. Dobrovolskiy,
• Maksym Kompaniiets,
• Roland Sachser,
• Fabrizio Porrati,
• Christian Gspan,
• Harald Plank and
• Michael Huth

Beilstein J. Nanotechnol. 2015, 6, 1082–1090, doi:10.3762/bjnano.6.109

• out easier to deposit self-assembled Co nanoparticles on top of Pt thin films [38] and thereby fabricate surface alloys formed at step edges of Pt single crystalline substrates. In that work [38], an increase of the coercive field and of the Co orbital magnetic momentum was observed and attributed to

Graphene on SiC(0001) inspected by dynamic atomic force microscopy at room temperature

• Mykola Telychko,
• Jan Berger,
• Zsolt Majzik,
• Pavel Jelínek and
• Martin Švec

Beilstein J. Nanotechnol. 2015, 6, 901–906, doi:10.3762/bjnano.6.93

• sample. KPFM parabola was measured by sweeping the bias voltage and measuring the Δf value [24]. In order to estimate the SLG corrugation we carried out large scale total energy density functional theory (DFT) calculations. We used local-orbital FIREBALL code [25][26]. FIREBALL uses an optimized [27

• ] spatially-confined pseudo-atomic numerical orbital basis set. In our case, an ss* basis set was used for the H atoms, a sp basis set for the Si and C atoms. The cutoff radii of the pseudo-atomic basis functions were as follows: R(H,s) = 4.5 a.u., R(H,s*) = 4.5 a.u., R(C,s) = 4.5 a.u, R(C,s) = 4.5 a.u., R(Si

Magnetic properties of self-organized Co dimer nanolines on Si/Ag(110)

• Lisa Michez,
• Kai Chen,
• Fabien Cheynis,
• Frédéric Leroy,
• Alain Ranguis,
• Haik Jamgotchian,
• Margrit Hanbücken and
• Laurence Masson

Beilstein J. Nanotechnol. 2015, 6, 777–784, doi:10.3762/bjnano.6.80

• -dimensional (2D) and one-dimensional (1D) Co nanostructures has shown that magnetic properties are highly size dependent, due to the low coordination of the atoms of atomic-scale nanostructures [1][18]. For such nanostructures, enhanced magnetic anisotropy energy (MAE) and orbital moment have been evidenced

• light gives access to the magnetization direction and magnitude of a specific element. According to the magnetic sum rules [38][39], the spin (μS) and orbital (μL) moments can indeed be quantitatively determined. In this work, we have applied the formalism described by Chen et al. [35] in order to

• evaluate the spin and orbital contributions to the magnetization of the Co nanolines. The number of holes in the Co 3d band is estimated to be 2.5, which corresponds to the average theoretical value for bulk Co [40][41]. Note that a similar value of 2.4 has been found for the case of Co adatoms on Pt(111

Statistics of work and orthogonality catastrophe in discrete level systems: an application to fullerene molecules and ultra-cold trapped Fermi gases

• Antonello Sindona,
• Michele Pisarra,
• Mario Gravina,
• Cristian Vacacela Gomez,
• Pierfrancesco Riccardi,
• Giovanni Falcone and
• Francesco Plastina

Beilstein J. Nanotechnol. 2015, 6, 755–766, doi:10.3762/bjnano.6.78

• particular, we consider the highest and lowest occupied MOs of the neutral molecule and some MOs of the ionized molecule to have similar binding energies relative to the perturbed Fermi level. The squared overlap between these states are listed in Table 1, while some of their orbital shapes are shown in

Chains of carbon atoms: A vision or a new nanomaterial?

• Florian Banhart

Beilstein J. Nanotechnol. 2015, 6, 559–569, doi:10.3762/bjnano.6.58

• carbon atoms [49]. By considering cumulene chains between two metal electrodes, Lang and Avouris [46] have found that even-number chains have a lower density of states (DOS) at the Fermi level than odd-number chains. In free chains (no contacts), the highest occupied molecular orbital (HOMO) is half

Raman spectroscopy as a tool to investigate the structure and electronic properties of carbon-atom wires

• Alberto Milani,
• Matteo Tommasini,
• Valeria Russo,
• Andrea Li Bassi,
• Andrea Lucotti,
• Franco Cataldo and
• Carlo S. Casari

Beilstein J. Nanotechnol. 2015, 6, 480–491, doi:10.3762/bjnano.6.49

• atom per unit cell, providing one electron from each 2pz orbital, thus forming a half-filled band of a 1D metal. As a consequence of Peierls distortion (driven by electron–phonon coupling and dimerization of the structure), an energy gap opens and the metallic character of cumulenes changes into the

Palladium nanoparticles anchored to anatase TiO₂ for enhanced surface plasmon resonance-stimulated, visible-light-driven photocatalytic activity

• Kah Hon Leong,
• Hong Ye Chu,
• Shaliza Ibrahim and
• Pichiah Saravanan

Beilstein J. Nanotechnol. 2015, 6, 428–437, doi:10.3762/bjnano.6.43

• absorbance spectrum was calculated by using the UV–vis diffuse reflectance spectra and it is shown in Figure 7. As predicted and according to theory, the absorption band shown by anatase TiO2 sample due to the charge-transfer absorption from the oxide anions 2p orbital valence band to the conduction band of

• 3d orbital of Ti4+ cations is below 400 nm [3][54][55]. Furthermore, anatase TiO2 showed almost zero absorption in the visible region as indicated in the spectrum. However, the deposition of Pd NPs caused a significant increase of the absorption in the visible region because of the surface plasmon

X-ray photoelectron spectroscopy of graphitic carbon nanomaterials doped with heteroatoms

• Toma Susi,
• Thomas Pichler and
• Paola Ayala

Beilstein J. Nanotechnol. 2015, 6, 177–192, doi:10.3762/bjnano.6.17

• level, each core state is expected to split into two components due to spin–orbit coupling, corresponding to orbital angular momentum quantum numbers of j = 1/2 and 3/2. The magnitude of the spin–orbit splitting is thought to be rather insensitive to the chemical environment and predicted by theory to

Spectroscopic mapping and selective electronic tuning of molecular orbitals in phosphorescent organometallic complexes – a new strategy for OLED materials

• Pascal R. Ewen,
• Jan Sanning,
• Tobias Koch,
• Nikos L. Doltsinis,
• Cristian A. Strassert and
• Daniel Wegner

Beilstein J. Nanotechnol. 2014, 5, 2248–2258, doi:10.3762/bjnano.5.234

• orbitals of Pt(II) complexes adsorbed on Au(111). The analysis showed that the molecules exhibit a peculiar localized strong hybridization that leads to partial depopulation of a dz² orbital, while the ligand orbitals are almost unchanged. We further found that substitution of functional groups at well

• orbitals were calculated in the gas phase with the Gaussian 09 package [34] using the PBE0 hybrid exchange-correlation functional [35] and the SDD basis set [36]. The molecular orbitals were visualized using the VMD 1.9 software. The orbital energies in the gas-phase calculations are computed with respect

• distribution agrees well with the spectroscopic maps seen around 2.0 V. Finally, the LUMO+1 is also localized mainly at the TL pyridine but now the orbital is antisymmetric with respect to the molecular symmetry axis. This is in very good agreement with the dI/dV distribution measured around 2.6 V. As a guide