Probing the electronic transport on the reconstructed Au/Ge(001) surface

• Franciszek Krok,
• Mark R. Kaspers,
• Alexander M. Bernhart,
• Marek Nikiel,
• Benedykt R. Jany,
• Paulina Indyka,
• Mateusz Wojtaszek,
• Rolf Möller and
• Christian A. Bobisch

Beilstein J. Nanotechnol. 2014, 5, 1463–1471, doi:10.3762/bjnano.5.159

• transport channel for electrons. Keywords: Au on Ge(001); electronic transport; multi probe STM; scanning tunnelling potentiometry; Introduction Structures consisting of single atoms represent the lower spatial limit for electronic circuits. On such a small scale, the electronic structure is dominated by

• current needs to be coupled to the atomic wires. At neighbouring terraces, the Au/Ge(001) wire structure is rotated by 90° and then a single layer step represents a domain boundary. Simultaneously, also the correlated electronic structure is rotated. Thus, the coupling between adjacent terraces can be

• (001) surface exhibits a two dimensional conductance channel on a micrometre-scale averaging across several Au-reconstructed 1D domains [10]. Scanning tunnelling microscopy (STM) and various STM-based methods are excellent tools to study the topographic structure, the electronic structure, and electron

Liquid fuel cells

• Grigorii L. Soloveichik

Beilstein J. Nanotechnol. 2014, 5, 1399–1418, doi:10.3762/bjnano.5.153

Sublattice asymmetry of impurity doping in graphene: A review

• James A. Lawlor and
• Mauro S. Ferreira

Beilstein J. Nanotechnol. 2014, 5, 1210–1217, doi:10.3762/bjnano.5.133

• interactions between graphene and Al, Ag, Au, Pt(111) substrates, all of which leave the electronic structure intact [61], whilst substrates such as Ni have considerably stronger interactions [62]. Another way to investigate the presence of sublattice asymmetry with dopants other than nitrogen is via ion

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

• nanocluster. To answer the questions raised above we determine the electronic structure and the optical spectra of the pollutant itself, and find where the deprotonation is more likely to take place. We also simulate the pollutant–catalyst system to analyze the binding configurations. We discuss the energy

• focuses on the optimized geometry and electronic structure of the free pollutants. The third subsection presents the binding of the pollutants to the titania nanocluster, the fourth presents the optical properties of the adsorbed pollutants, and the last subsection attempts to explain the experimental

• on the catalyst, the electronic states were accurately computed by using DZVP basis sets [40]. The Gaussian03 package [41] was used in all calculations. Free pollutants – electronic structure and optical properties During the photocatalytic degradation the benzene derivatives (phenol, Ph, benzoic

Growth and characterization of CNT–TiO₂ heterostructures

• Yucheng Zhang,
• Ivo Utke,
• Johann Michler,
• Gabriele Ilari,
• Marta D. Rossell and
• Rolf Erni

Beilstein J. Nanotechnol. 2014, 5, 946–955, doi:10.3762/bjnano.5.108

• . The third mechanism was proposed by Pyrgiotakis [13], in which the C–O–Ti bond introduces energy states in the band gap of TiO2, and is attributed to the extended absorption of longer wavelength light. In addition, they also found that the electronic structure of CNTs may have a bigger effect on the

• -nanometer spatial resolution, which helps to understand the nucleation of diamond [53]. Suenaga et al. have performed in-situ bending of SW-CNTs in TEM and observed a change in the C_K edge ELNES at kinks of the CNT bundles, indicating the change of the electronic structure with the deformation [54

• ]. Theoretical calculations based on density functional theory (DFT) can be used to simulate the details in ELNES and to fundamentally predict the atomic and the electronic structure. Depending on the atomic potentials defined in the calculation, methods based on the band theory, the molecular orbitals or the

An analytical approach to evaluate the performance of graphene and carbon nanotubes for NH₃ gas sensor applications

• Elnaz Akbari,
• Vijay K. Arora,
• Aria Enzevaee,
• Mohamad. T. Ahmadi,
• Mehdi Saeidmanesh,
• Mohsen Khaledian,
• Hediyeh Karimi and
• Rubiyah Yusof

Beilstein J. Nanotechnol. 2014, 5, 726–734, doi:10.3762/bjnano.5.85

• be formed for implementation by applying positive or negative gate voltage and can be useful from the application perspective [35]. Gas molecules can modulate the electronic structure of graphene in diverse ways. The adsorption of CO2 and O2 converts the system to p-type semiconductor while the

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

• solution for the photosensitizers to anchor. The hybridization of exfoliated nanosheets with nanosized photosensitizers often shows a tunable electronic structure and new physicochemical properties. All these features attribute to a promising future of nanostructure sensitization in the ion-exchangeable

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

• applied in the framework of electronic structure theory in order to assess the properties of nanoparticles, nanostructures or interfaces [11][12][13][14][15]. Today, several approaches are available for modelling the full details of the electronic structure in electrochemical phenomena. The most common

• ” [16], and which we previously denoted as “constant charge approach” [13], allows to use the results of a single electronic structure calculation for all potentials [20][21]. Furthermore, this approach is also very convenient for periodic boundary calculations as in this case the models are restricted

• prominent non-faradaic electrochemical modification of catalytic activity (NEMCA) effect [23]. Only in recent years, attempts have been made to go beyond the pure thermodynamical approximation, explicitly including the electrochemical potential into the electronic structure calculation by means of adding or

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

• showed no obvious change when higher cut-off energy and more k-points were adopted. The electronic structure calculation was carried out by using the optimized geometric structure. Measurements of photocatalytic activity The photocatalytic activity of the as-prepared samples was evaluated by the

CoPc and CoPcF₁₆ on gold: Site-specific charge-transfer processes

• Fotini Petraki,
• Heiko Peisert,
• Johannes Uihlein,
• Umut Aygül and
• Thomas Chassé

Beilstein J. Nanotechnol. 2014, 5, 524–531, doi:10.3762/bjnano.5.61

• spectroscopy (UPS) as well as X-ray absorption spectroscopy (XAS). Combined XPS and XAES measurements can be employed as a tool to study the contribution of the polarization energy to chemical shifts at interfaces. XAS gives valuable information about the unoccupied electronic structure and the hybridization

• information about the unoccupied electronic structure is accessible. In Figure 5 we compare F K-edge spectra for two different film thicknesses acquired at a grazing and at a normal incidence of radiation. From N K absorption spectra (data not shown) we conclude that the molecules are flat lying on the

Tensile properties of a boron/nitrogen-doped carbon nanotube–graphene hybrid structure

• Kang Xia,
• Haifei Zhan,
• Ye Wei and
• Yuantong Gu

Beilstein J. Nanotechnol. 2014, 5, 329–336, doi:10.3762/bjnano.5.37

• and can form strong valence bonds with carbon atoms, are the most frequently used doping elements for carbon-based materials [11]. The presence of boron and nitrogen atom induce significant variations in the electronic structure of graphene layer, which was shown by changes in the Raman spectra [12

Atomic layer deposition, a unique method for the preparation of energy conversion devices

• Julien Bachmann

Beilstein J. Nanotechnol. 2014, 5, 245–248, doi:10.3762/bjnano.5.26

• in batteries; ALD for separation and protection, in particular to prevent erosion or corrosion in electrochemical devices; ALD for interface engineering, for example defect passivation in solar cells or prevention of charge recombination by tunnel barriers, and for influencing the electronic

• structure of an underlying semiconductor. This Thematic Series will certainly provide the reader with novel ideas for exploiting ALD in the energy realm, and spur further original work in this rapidly developing research area. After its industrial application in electroluminescent displays, semiconductor

Change of the work function of platinum electrodes induced by halide adsorption

• Florian Gossenberger,
• Tanglaw Roman,
• Katrin Forster-Tonigold and
• Axel Groß

Beilstein J. Nanotechnol. 2014, 5, 152–161, doi:10.3762/bjnano.5.15

• approximately 0.4 ML. By analyzing the underlying electronic structure, we were able to show that this behavior can be explained through a combination of charge transfer and polarization effects of the adsorbate layer. We have now extended this previous study by considering the adsorption of fluorine, chlorine

• halogen adsorption on Pt(111) as a function of the coverage was studied by electronic structure calculations. In general, because of their electronegativity, the adsorption of halogens is associated with a charge transfer from the metal substrate to the adsorbate layer. In the case of fluorine adsorption

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

• have considered either non-periodic (cluster-type) systems or small unit cells. This has made the simulation of extended defects challenging and subject to questionable approximations, and possibly even spurious image–image interaction or finite size effects. Furthermore, the electronic structure of

Influence of the adsorption geometry of PTCDA on Ag(111) on the tip–molecule forces in non-contact atomic force microscopy

• Gernot Langewisch,
• Jens Falter,
• André Schirmeisen and
• Harald Fuchs

Beilstein J. Nanotechnol. 2014, 5, 98–104, doi:10.3762/bjnano.5.9

• tunneling microscopy and scanning tunneling spectroscopy studies of PTCDA adsorbed on Ag(111) have revealed differences in the electronic structure of the molecules depending on their adsorption geometry. In the work presented here, high-resolution 3D force spectroscopy measurements at cryogenic

• simulations, it was found that the differences between the two possible adsorption geometries of PTCDA on the Ag(111) substrate affect the electronic structure of the molecules [2][3][4][5]. The chemical nature of the molecule–substrate bond leads to a charge transfer from the metal surface into the former

• , a significant difference in the intensity of the two adsorption geometries can be observed, which is caused by the different electronic structure as described above. In contrast, this effect is not detectable in the AFM topography image in Figure 1b. However, as discussed above, the reason might be

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

• spectroscopy. The Ti precursor, titanium isopropoxide, was used in combination with H2O on Si/SiO2 substrates that were heated at 200 °C. The low growth rate (0.15 Å/cycle) and the in situ characterization permitted to follow changes in the electronic structure of TiO2 in the sub-nanometer range, which are

STM tip-assisted engineering of molecular nanostructures: PTCDA islands on Ge(001):H surfaces

• Amir A. Ahmad Zebari,
• Marek Kolmer and
• Jakub S. Prauzner-Bechcicki

Beilstein J. Nanotechnol. 2013, 4, 927–932, doi:10.3762/bjnano.4.104

• system [20]. Most of the islands have a height of 2.1 nm, what corresponds to 6 molecular layers. Insight into the electronic structure of the studied system is obtained by rt STS measurements (see Figure 1b). For a bare germanium surface a band gap of ≈0.2 eV is obtained, in fair agreement with

• window from −2.5 V to 1.7 V (corresponding to the semiconducting energy gap of PTCDA molecules) of the STS curves. This means that the electronic structure of PTCDA is unperturbed by the electronic properties of the underlying substrate. Figure 1c–f show a set of four consecutive scans of the same area

Adsorption of the ionic liquid [BMP][TFSA] on Au(111) and Ag(111): substrate effects on the structure formation investigated by STM

• Benedikt Uhl,
• Florian Buchner,
• Dorothea Alwast,
• Nadja Wagner and
• R. Jürgen Behm

Beilstein J. Nanotechnol. 2013, 4, 903–918, doi:10.3762/bjnano.4.102

• with the surface results in modifications of the electronic structure compared to that in condensed thicker layers. While XPS data exist only for adsorption on Au(111), we expect similar behavior also for adsorption on Ag(111). 2) Upon cooling the sample to 100 K, molecular motion in the adlayer is

Large-scale atomistic and quantum-mechanical simulations of a Nafion membrane: Morphology, proton solvation and charge transport

• Pavel V. Komarov,
• Pavel G. Khalatur and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2013, 4, 567–587, doi:10.3762/bjnano.4.65

• which local density fields are employed as collective variables for simulating the structural evolution of phase-separation morphologies [11][48][49][50][51][52][53]. Several different quantum mechanics approaches have been used in attempts to understand electronic structure and proton conduction in

• redistribution and the change of coordinates of classical atoms, i.e., the Schrödinger and Newton equations are solved in combination at each time step. The approach consists in the determination of forces affecting atoms "on the fly" from electronic structure calculations based on the first (ab initio) quantum

• similar to BOMD, the electrons are kept on the Born–Oppenheimer surface, corresponding to their instantaneous electronic ground state, by means of explicit electronic structure optimization after each MD step [89]. This implies that the time step can be chosen to be as large as the particular ionic

Nanoglasses: a new kind of noncrystalline materials

• Herbert Gleiter

Beilstein J. Nanotechnol. 2013, 4, 517–533, doi:10.3762/bjnano.4.61

• comparison to the corresponding melt-quenched glass) by (1) a reduced (up to about 10%) density, (2) a reduced (up to about 20%) number of nearest-neighbor atoms and (3) a different electronic structure. Due to their new kind of atomic and electronic structure, the properties of nanoglasses may be modified

• adjacent glassy regions). This enhanced free volume in the glass–glass interfaces seems to agree with recent density measurements [19]. Electronic structure of nanoglasses The different atomic arrangements in the glass–glass interfaces and in the adjacent glassy regions as well as interfacial segregation

• effects seem to result in different electronic structures in both regions. A first indication of the different electronic structure was the observation [3] that the Mössbauer isomer shift (IS) of the interfacial component of PdSiFe glasses (Figure 10) was larger than the IS value of the melt-cooled glass

Synthesis and thermoelectric properties of Re₃As_6.6In_0.4 with Ir₃Ge₇ crystal structure

• Valeriy Y. Verchenko,
• Anton S. Vasiliev,
• Alexander A. Tsirlin,
• Vladimir A. Kulbachinskii,
• Vladimir G. Kytin and
• Andrei V. Shevelkov

Beilstein J. Nanotechnol. 2013, 4, 446–452, doi:10.3762/bjnano.4.52

• , and the atomic parameters are shown in Table 2. Selected interatomic distances are listed in Table 3. Electronic-structure calculations The FPLO (full potential local orbitals) code was utilized for the electronic-structure calculations [16]. FPLO performs density functional calculations with the

• atoms occupying the 16f site, with a bond distance of 2.538(5) Å. Clearly, indium does not favor such a short bond to arsenic and, therefore, avoids the occupation of this site. Electronic structure, magnetic and thermoelectric properties The computed density of states for Re3As7 is shown in Figure 5

• properties of the S1 sample as a function of temperature. Solid lines are drawn to guide the eye. Crystallographic data from the powder diffraction experiment for S1. Atomic coordinates and displacement parameters for S1. Selected interatomic distances for S1. Re3As7 crystallographic data used for electronic

Magnetic anisotropy of graphene quantum dots decorated with a ruthenium adatom

• Igor Beljakov,
• Velimir Meded,
• Franz Symalla,
• Karin Fink,
• Sam Shallcross and
• Wolfgang Wenzel

Beilstein J. Nanotechnol. 2013, 4, 441–445, doi:10.3762/bjnano.4.51

• visible: while the Ru moment increases at the edge sites for the AGQD, as there are fewer C atoms with which to share the unpaired electrons of Ru, towards the edge sites of the ZGQD the moment, in contrast, is seen to decrease. In short, the electronic structure of the graphene substrate determines the

• . Note that the edge positions of the ZGQD have the lowest adatom moment (and so lowest EIO) while, in contrast, on the AGQD these positions have the highest adatom moment and EIO. Points that deviate from the overall trend reflect a specific electronic structure associated with low symmetry positions of

• out of plane. If EIO is positive, the easy axis points along the direction 2. The in-plane MAE (EIP) is defined as The EIP is per definition always positive and would be equal to zero for an adatom on an infinite graphene sheet, due to the underlying symmetry. Results We first consider the electronic

Kelvin probe force microscopy of nanocrystalline TiO₂ photoelectrodes

• Alex Henning,
• Gino Günzburger,
• Res Jöhr,
• Yossi Rosenwaks,
• Biljana Bozic-Weber,
• Catherine E. Housecroft,
• Edwin C. Constable,
• Ernst Meyer and
• Thilo Glatzel

Beilstein J. Nanotechnol. 2013, 4, 418–428, doi:10.3762/bjnano.4.49

• ) TiO2 have been investigated with such a macroscopic Kelvin probe (KP) revealing details about the electronic structure [21][22][23], trap states [24], the surface dipole [25], charge-carrier dynamics [26], and indicating changes upon chemical treatments [24][27][28][29]. KP studies have helped to

Photocatalytic antibacterial performance of TiO₂ and Ag-doped TiO₂ against S. aureus. P. aeruginosa and E. coli

• Kiran Gupta,
• R. P. Singh,
• Ashutosh Pandey and
• Anjana Pandey

Beilstein J. Nanotechnol. 2013, 4, 345–351, doi:10.3762/bjnano.4.40

• and enhance the photocatalytic activity. Photoluminescence spectroscopy (PL) Photoluminescence spectroscopy (PL) is a practical method for probing the electronic structure of nanomaterials, the transfer behaviour of the photoexcited electron–hole pairs in semiconductors, and the rate of recombination

• comparison to those of the TiO2 nanoparticles because the metallic silver ions cause some changes in the electronic structure of the Ag-containing titanium dioxide nanoparticles [20]. Moreover, the PL intensity of Ag-doped TiO2 (7%) is lower in comparison to the case of 3% doping of Ag, and this can be

Influence of the solvent on the stability of bis(terpyridine) structures on graphite

• Daniela Künzel and
• Axel Groß

Beilstein J. Nanotechnol. 2013, 4, 269–277, doi:10.3762/bjnano.4.29

• computationally expensive statistical averages have to be performed in order to evaluate free-energy differences. Although electronic structure calculations based on density functional theory can reproduce the properties of planar arrangements of aromatic molecules satisfactorily [15][16][17][18], the large size

• of the considered systems and the requirement to perform thermal averages make first-principles electronic-structure calculations computationally prohibitively expensive. Therefore we employed classical force fields as included in the Forcite module of the Accelrys’ Materials Studio package to