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

Hybrid spin-crossover nanostructures

• Carlos M. Quintero,
• Gautier Félix,
• Iurii Suleimanov,
• José Sánchez Costa,
• Gábor Molnár,
• Lionel Salmon,
• William Nicolazzi and
• Azzedine Bousseksou

Beilstein J. Nanotechnol. 2014, 5, 2230–2239, doi:10.3762/bjnano.5.232

• proposed two mechanisms: first, since the oscillator strength of the charge transfer (CT) bands increases in the LS state, it is possible that the injected electrons transit from the π orbital of the dpp ligand to the d orbital of the iron centers, giving an additional electron transport path from the

• cathode to the anode through the SCO complex. Second, a shift in the energy level of the molecular orbital concerning the electron transport in the SCO complex relative to that of Chl a (Figure 6b) [30] is possible. Thus, at high temperatures (HS state) the injected electrons effectively excite the Chl a

• molecules, leading to EL emission. Conversely, at low temperatures (LS state) the electron transport orbital of the [Fe(dpp)2](BF)4 shifts to a level lower than that of Chl a and as a result, the electrons flow exclusively into the SCO complex, preventing the formation of excited Chl a. Even though the

UHV deposition and characterization of a mononuclear iron(III) β-diketonate complex on Au(111)

• Irene Cimatti,
• Silviya Ninova,
• Valeria Lanzilotto,
• Luigi Malavolti,
• Luca Rigamonti,
• Brunetto Cortigiani,
• Matteo Mannini,
• Elena Magnano,
• Federica Bondino,
• Federico Totti,
• Andrea Cornia and
• Roberta Sessoli

Beilstein J. Nanotechnol. 2014, 5, 2139–2148, doi:10.3762/bjnano.5.223

• larger discrepancies observed at higher binding energies. By plotting the projected density of states (PDOS) on the ligands and the iron ion (see Figure 3a), it is evident that dpm− ligands provide the main orbital contributions to the energy region where the molecular peaks (a, b, c, d) can be

• @Au(111) (Figure 7c) matches very closely to the observed tetra-lobed units with no detectable contribution from the iron dz2 orbital. FeOH(dpm)2@Au(111) also affords a tetra-lobed pattern, but with an extra spot in the middle. This shows that FeOH(dpm)2 is unlikely to be the end product of Fe(dpm)3

Patterning a hydrogen-bonded molecular monolayer with a hand-controlled scanning probe microscope

• Matthew F. B. Green,
• Taner Esat,
• Christian Wagner,
• Philipp Leinen,
• Alexander Grötsch,
• F. Stefan Tautz and
• Ruslan Temirov

Beilstein J. Nanotechnol. 2014, 5, 1926–1932, doi:10.3762/bjnano.5.203

• voltage pulses of 3–6 V (applied to the sample) and by crashing 10–30 Å deep into the clean Ag(111) surface whilst simultaneously applying a voltage of 0.1–1 V. The cleanness of the tip was validated by STM imaging of the former lowest unoccupied molecular orbital (LUMO) of PTCDA [10] and spectroscopy of

Spin annihilations of and spin sifters for transverse electric and transverse magnetic waves in co- and counter-rotations

• Hyoung-In Lee and
• Jinsik Mok

Beilstein J. Nanotechnol. 2014, 5, 1887–1898, doi:10.3762/bjnano.5.199

• analyze both Poynting-vector flows and orbital and spin parts of the energy flow density for the combined fields. Consequently, we find not only enhancements but also cancellations between the two modes. To our surprise, the photon spins in the azimuthal direction exhibit a complete annihilation for the

• counter-rotational case even if the intensities of the colliding waves are of different magnitudes. In contrast, the orbital flow density disappears only if the two intensities satisfy a certain ratio. In addition, the concepts of spin sifters and enantiomer sorting are illustrated. Keywords: angular

• momentum; multiplexing; nanoparticle; orbital; Poynting; spin; trajectory; Introduction Electromagnetic (EM) waves are now fairly well understood at least in terms of angular momentum (AM) and Poynting vector (PV). For instance, the AM of spin-one photons is divisible into the spin and orbital parts [1][2

Carbon-based smart nanomaterials in biomedicine and neuroengineering

• Antonina M. Monaco and
• Michele Giugliano

Beilstein J. Nanotechnol. 2014, 5, 1849–1863, doi:10.3762/bjnano.5.196

• thanks to a rearrangement of its electron configuration: One of its 2s electrons “moves” into the empty 2p orbital, giving rise to four bonds due to four hybrid orbitals. The three possible hybridisations (sp, sp2 and sp3) differ according to the number of p orbitals mixed with the s orbital, and

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

• interact easier than narrow nanotubes with benzene due to the better geometric match between a planar molecule such as benzene and the not very pronounced π-orbital misalignment of bigger CNTs. The chirality of CNTs, that depends on the way carbon hexagons are arranged in the nanotube (see Figure 1), and

• 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

Numerical investigation of the effect of substrate surface roughness on the performance of zigzag graphene nanoribbon field effect transistors symmetrically doped with BN

• Majid Sanaeepur,
• Arash Yazdanpanah Goharrizi and
• Mohammad Javad Sharifi

Beilstein J. Nanotechnol. 2014, 5, 1569–1574, doi:10.3762/bjnano.5.168

• orbital of carbon is responsible for the electronic properties of graphene. Although the SR modulates both the distance and angle between the pz orbitals through, stretching and bending of C–C bonds, respectively, the effect of bending is negligible [36]. Therefore, in order to incorporate the effect of

Enhanced photocatalytic hydrogen evolution by combining water soluble graphene with cobalt salts

• Jing Wang,
• Ke Feng,
• Hui-Hui Zhang,
• Bin Chen,
• Zhi-Jun Li,
• Qing-Yuan Meng,
• Li-Ping Zhang,
• Chen-Ho Tung and
• Li-Zhu Wu

Beilstein J. Nanotechnol. 2014, 5, 1167–1174, doi:10.3762/bjnano.5.128

• , corresponding to the Co 2p orbital (Supporting Information File 1, Figure S3). The cobalt lines in the spectra, however, were assigned to cobalt(II) [65], not to cobalt(0). This is different from the TEM results and in contrast to the grown cobalt metal nanoparticles on graphene [66]. ICP-MS measurements were

DFT study of binding and electron transfer from colorless aromatic pollutants to a TiO₂ nanocluster: Application to photocatalytic degradation under visible light irradiation

• Corneliu I. Oprea,
• Petre Panait and
• Mihai A. Gîrţu

Beilstein J. Nanotechnol. 2014, 5, 1016–1030, doi:10.3762/bjnano.5.115

• difference between the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) is larger for all pollutants than the calculated band gap of the semiconductor. As a result, the absorption spectra of the free pollutants have peaks further in the UV region than the catalyst

• intensity is extremely weak. The stronger UV–vis absorption bands of the adsorbed pollutants are located below 475 nm. Except for BA, whose key orbital seems to be HOMO-1, for the other adsorbed pollutants the transitions with noticeable oscillator strengths are from the HOMO to states above the conduction

• influence the transfer rate is the matrix element, which, in turn, can be correlated with the overlap integral between the two states. The emphasis on the orbital overlap was underlined long ago [63] suggesting that the π* orbitals of the carboxy group would promote rapid electron injection into the

Volcano plots in hydrogen electrocatalysis – uses and abuses

• Paola Quaino,
• Fernanda Juarez,
• Elizabeth Santos and
• Wolfgang Schmickler

Beilstein J. Nanotechnol. 2014, 5, 846–854, doi:10.3762/bjnano.5.96

• at the equilibrium potential; have a d band which spans the Fermi level; have a strong and long-ranged interaction between the d band and the hydrogen 1s orbital. A long range is important, because the electron transfer to the proton occurs at a certain distance, of the order of 0.5 Å, from the

• enough to make a contribution to the binding of hydrogen. However, as a third row element the orbitals of copper are compact; therefore the overlap with the hydrogen 1s orbital is short-ranged. As shown in Figure 3, the interaction of the copper d band with hydrogen has almost dropped to zero at a

• up and spin down are shifted with respect to each other, even though they have the same shape (see Figure 4). This has a marked effect on the spin polarization of a hydrogen atom in front of the surface. On the densest-packed surface of most metals, spin polarization of the H1s orbital vanishes at

Nanostructure sensitization of transition metal oxides for visible-light photocatalysis

• Hongjun Chen and
• Lianzhou Wang

Beilstein J. Nanotechnol. 2014, 5, 696–710, doi:10.3762/bjnano.5.82

• bandgap, which is, narrower and has a higher CB minimum or lowest unoccupied molecular orbital (LUMO) in comparison with wide-bandgap transition metal oxides. Because a photosensitizer normally has a narrow bandgap, it can absorb the visible sunlight and even the infrared sunlight to generate electron

• also be utilized as “organic dyes” for the conversion of light to current under visible and/or near-infrared light irradiation [90][91][92]. These gold clusters with tens of atoms are much smaller than gold nanoparticles, which caused gold clusters to exhibit no localized SPR but a molecular orbital

• splitting [105]. The mechanisms in these research works are very similar. As shown in Figure 8a, ZnWO4 can absorb UV light to produce photogenerated electron–hole pairs, and then the holes transfer from the VB of ZnWO4 to the highest occupied molecular orbital (HOMO) of graphene because the VB position of

Constant chemical potential approach for quantum chemical calculations in electrocatalysis

• Wolfgang B. Schneider and
• Alexander A. Auer

Beilstein J. Nanotechnol. 2014, 5, 668–676, doi:10.3762/bjnano.5.79

• approximations by the orbital energies. Furthermore, in calculating the free energy of a system, a Fermi–Dirac distribution function is applied to obtain the occupation numbers at a given temperature (“Fermi smearing”). Here, the chemical potential appears as a parameter for the Fermi smearing in the form of the

• on the number of electrons is plotted according to Equation 2. For the red/solid exact curve, the potential was obtained by Equation 2 from converged calculations using fractional number of electrons and hence, is the exact μ(N). The orbital energies εi obtained from calculations with a N of 15, 16

Effects of the preparation method on the structure and the visible-light photocatalytic activity of Ag₂CrO₄

• Difa Xu,
• Shaowen Cao,
• Jinfeng Zhang,
• Bei Cheng and
• Jiaguo Yu

Beilstein J. Nanotechnol. 2014, 5, 658–666, doi:10.3762/bjnano.5.77

• limitation of DFT calculation [63][64]. The electronic structure of Ag2CrO4 indicates that the valence band mainly consists of occupied Ag 4d and O 2p orbitals, and the conduction band mainly comes from the empty Cr 3d orbital, which means that Cr makes an important contribution to the bottom of the

• conduction band. It has been found that Ag is one of the elements that are able to form a valence band position higher than the O 2p orbital [65]. It has been demonstrated that Cr has the potential ability to lower down the bottom of the conduction band [40][66]. Thereby the synergistic effect of Ag and Cr

• adsorbed O2 to yield O2•−, meanwhile the photogenerated holes on the VB of Ag2CrO4 also can not oxidize H2O to form OH• due to their insufficient reduction (for electron) and oxidation ability (for hole). In addition, the energy level of the lowest unoccupied molecular orbital (LUMO) and the highest

Charge and spin transport in mesoscopic superconductors

• M. J. Wolf,
• F. Hübler,
• S. Kolenda and
• D. Beckmann

Beilstein J. Nanotechnol. 2014, 5, 180–185, doi:10.3762/bjnano.5.18

• , the effect of the applied field is mostly orbital pair breaking, and the Zeeman splitting of the density of states does not play a significant role. In Figure 2a, we show the nonlocal conductance gnl of a pair of contacts at low temperature and for bias voltages above the energy gap Δ ≈ 200 μeV of the

Core level binding energies of functionalized and defective graphene

• Toma Susi,
• Markus Kaukonen,
• Paula Havu,
• Mathias P. Ljungberg,
• Paola Ayala and
• Esko I. Kauppinen

Beilstein J. Nanotechnol. 2014, 5, 121–132, doi:10.3762/bjnano.5.12

• substitutional doping, which we will not discuss here, the functionalization of graphene by, e.g., hydrogenation [1][2] and oxygenation [3][4] has been a topic of intense research. These treatments result in –H, –O, or –OH groups bonded to the carbon atoms, the orbital hybridization of which is changed from sp2

• vacancy lowers the calculated C 1s energies of the carbon atom that is attached to the functional group significantly. This is likely due to the effect of the missing electron in the pz orbital of the vacancy. Concerning the oxygen 1s core level binding energies, we chose in Table 1 to use the calculated

• energy differences method were implemented into GPAW by Ljungberg et al. [22][23], and into SIESTA by García-Gil et al. [33]. The core-hole setup (similar to a pseudo-potential) is created by using a spin-paired atomic calculation with the occupation of the core orbital decreased by one and held fixed

Quantum size effects in TiO₂ thin films grown by atomic layer deposition

• Massimo Tallarida,
• Chittaranjan Das and
• Dieter Schmeisser

Beilstein J. Nanotechnol. 2014, 5, 77–82, doi:10.3762/bjnano.5.7

• of feature C. Finally, the line shape of the 3 nm film is very similar to that observed in anatase TiO2 [10]. Vayssieres et al. found that quantum size effects in TiO2 NPs with an average diameter of 2 nm induce a change in the character of the conduction band orbital with a strengthening of the Ti

• calculations performed by Wu et al. [27] in the framework of the full multiple scattering theory and the tight-binding linear muffin-tin orbital band-structure method showed the presence of the higher energy tail only for large clusters, which is indicative of a long-range order. On the other hand, the

• 1.5 nm to 2.25 nm. As mentioned above, the origin of this feature was attributed to hybridized Ti 3d/O 2p states, for which the two peaks appear because the Ti 3d orbital is split into t2g and eg bands by the ligand-field. The shape of 0.75 nm and 1.5 nm TiO2 films compares very well with that found

Dye-doped spheres with plasmonic semi-shells: Lasing modes and scattering at realistic gain levels

• Nikita Arnold,
• Boyang Ding,
• Calin Hrelescu and
• Thomas A. Klar

Beilstein J. Nanotechnol. 2013, 4, 974–987, doi:10.3762/bjnano.4.110

• undoped semi-shell structure (Figure 3b), the near field distribution at 519.1 nm (Figure 8c) looks very different and resembles an (l = 3, m = 3) orbital. Clearly, this eigen-resonance is easily overlooked in experiments, in which semi-shells with insufficient or no gain are investigated because it would