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

Photoresponse from single upright-standing ZnO nanorods explored by photoconductive AFM

• Igor Beinik,
• Markus Kratzer,
• Astrid Wachauer,
• Lin Wang,
• Yuri P. Piryatinski,
• Gerhard Brauer,
• Xin Yi Chen,
• Yuk Fan Hsu,
• Aleksandra B. Djurišić and
• Christian Teichert

Beilstein J. Nanotechnol. 2013, 4, 208–217, doi:10.3762/bjnano.4.21

• believe that this phenomenon should be considered as a current-induced electrochemical process as we will argue in the discussion. In order to gain insight into the electronic structure of single upright standing ZnO NRs, we measured the spectral characteristics of the photocurrent by means of PC-AFM. The

Electronic and transport properties of kinked graphene

• Jesper Toft Rasmussen,
• Tue Gunst,
• Peter Bøggild,
• Antti-Pekka Jauho and
• Mads Brandbyge

Beilstein J. Nanotechnol. 2013, 4, 103–110, doi:10.3762/bjnano.4.12

• efficient barriers for electron transport. In particular, two parallel kink lines form a graphene pseudo-nanoribbon structure with a semimetallic/semiconducting electronic structure closely related to the corresponding isolated ribbons; the ribbon band gap translates into a transport gap for electronic

• crucial to modify the semimetallic electronic structure of graphene to exploit its full potential for many electronic applications: a band gap can be introduced by nanostructuring graphene. A common approach towards engineering the electronic structure is to form quasi-1D graphene in the form of

• nanoribbons (GNR) [2]. The electronic structure of GNRs depends on width, direction and edge structure – all parameters that to some degree can be controlled. GNRs can be formed by etching [2], by unzipping carbon nanotubes (CNTs) [3], or ultimately be grown with atomic-scale precision by using self-assembly

Nanostructure-directed chemical sensing: The IHSAB principle and the dynamics of acid/base-interface interaction

• James L. Gole and
• William Laminack

Beilstein J. Nanotechnol. 2013, 4, 20–31, doi:10.3762/bjnano.4.3

• basicity of the decorated interface. This process changes the interaction of the interface with the analyte. The observed change to the more basic oxinitrides does not represent a simple increase in surface basicity but appears to involve a change in molecular electronic structure, which is well explained

• semiconductor. When such properties are not already available, it is possible to use advanced computational chemistry approaches for their prediction, to improve our understanding of the dynamics of electron transduction across the interface, and to analyze the changes in molecular electronic structure that

• deposition of selected nanostructured islands (Figure 1, red dots). These surface-attached nanoparticles (see Experimental section) possess unique size-dependent and electronic-structure properties that form a basis for changing the sensitivity for exposure to specific gases relative to that of the porous

Structural and electronic properties of oligo- and polythiophenes modified by substituents

• Simon P. Rittmeyer and
• Axel Groß

Beilstein J. Nanotechnol. 2012, 3, 909–919, doi:10.3762/bjnano.3.101

• have been studied by using periodic density functional theory calculations. We have in particular focused on the effect of substituents on the electronic structure of thiophenes. Whereas singly bonded substituents, such as methyl, amino or nitro groups, change the electronic properties of thiophene

• electronic structure of polymers is crucial. In this regard, a directed manipulation of the band gap to tailor the electronic properties is very desirable. Considering the significant potential of organic chemistry at synthesizing and manipulating compounds, there is definitely a demand for a better

• understanding of how the electronic structure of compounds such as PTp can be manipulated by using these tools. There have been already several studies addressing the electronic structure of thiophenes with electronic structure methods [13][14][15][16][17][18][19][20]. In these computational studies, typically

Towards atomic resolution in sodium titanate nanotubes using near-edge X-ray-absorption fine-structure spectromicroscopy combined with multichannel multiple-scattering calculations

• Carla Bittencourt,
• Peter Krüger,
• Maureen J. Lagos,
• Xiaoxing Ke,
• Gustaaf Van Tendeloo,
• Chris Ewels,
• Polona Umek and
• Peter Guttmann

Beilstein J. Nanotechnol. 2012, 3, 789–797, doi:10.3762/bjnano.3.88

• specific spectral features in the O K-edge and Ti L-edge with oxygen atoms in distinct sites within the lattice. These can even be distinguished from the contribution of different hydroxyl groups to the electronic structure of the (Na,H)TiNTs. Keywords: multichannel multiple scattering; nanotubes; NEXAFS

• resolution in similar techniques with lower spectral resolution [9][10]. We investigate here the electronic structure of sodium titanate nanotubes ((Na,H)TiNTs) by means of near-edge X-ray-absorption fine-structure spectroscopy (NEXAFS) coupled with first-principles NEXAFS calculations (density functional

• structures and oxidation states. Here, the electronic structure of the nanotubes is discussed in terms of the ligand field splitting of the Ti ions and the connectivity of the TiO6 octahedral network. Among the different structures proposed for these nanotubes [13][14][15][16][17], it is currently accepted

Spontaneous dissociation of Co₂(CO)₈ and autocatalytic growth of Co on SiO₂: A combined experimental and theoretical investigation

• Kaliappan Muthukumar,
• Harald O. Jeschke,
• Roser Valentí,
• Evgeniya Begun,
• Johannes Schwenk,
• Fabrizio Porrati and
• Michael Huth

Beilstein J. Nanotechnol. 2012, 3, 546–555, doi:10.3762/bjnano.3.63

• less stable by 6.9 kcal/mol with respect to the C2v isomer compared to the reported value of 5.8 kcal/mol [27]. Electronic-structure analysis indicates that the highest occupied orbital (HOMO) is dominated by Co 3d orbitals (Figure 5c), and the lowest unoccupied orbital (LUMO) has a significant

X-ray absorption spectroscopy by full-field X-ray microscopy of a thin graphite flake: Imaging and electronic structure via the carbon K-edge

• Carla Bittencourt,
• Adam P. Hitchock,
• Xiaoxing Ke,
• Gustaaf Van Tendeloo,
• Chris P. Ewels and
• Peter Guttmann

Beilstein J. Nanotechnol. 2012, 3, 345–350, doi:10.3762/bjnano.3.39

• combined with full-field transmission X-ray microscopy can be used to study the electronic structure of graphite flakes consisting of a few graphene layers. The flake was produced by exfoliation using sodium cholate and then isolated by means of density-gradient ultracentrifugation. An image sequence

• properties of graphene in 2004 by Geim and Novoselov triggered intense interest in its electronic structure [1][2][3][4][5][6][7][8][9][10][11]. A key aspect of the electronic structure, namely understanding how the graphene band structure is altered by impurity doping introduced during the synthesis

• image and to study the electronic structure of a free-standing thin graphite flake produced by means of density-gradient ultracentrifugation (DGU) [20]. In the DGU process the bile salt sodium cholate (C24H39O5Na) is used to promote graphite exfoliation, resulting in graphene–surfactant complexes having

Models of the interaction of metal tips with insulating surfaces

• Thomas Trevethan,
• Matthew Watkins and
• Alexander L. Shluger

Beilstein J. Nanotechnol. 2012, 3, 329–335, doi:10.3762/bjnano.3.37

• with the NaCl surface, with calculations employing exclusively plane-wave basis sets and a fully periodic tip model, and demonstrate that the electronic structure of the tip model employed can have a significant quantitative effect on calculated forces when the tip and surface are clearly separated

• effect of the DFT methodology and the electronic structure of the tip model on the accuracy of the calculations of tip–surface forces. The plan of the rest of the paper is as follows: The next section describes the methodology employed; the third section describes the results of the calculations; and in

• depressions to Na+ ion positions. To investigate both the contribution of the electronic structure of the tip and the type of simulation method to the interaction between a metallic tip and an ionic surface, we calculated the changes in total energy as a function of tip position for the periodic Cr tip model

Graphite, graphene on SiC, and graphene nanoribbons: Calculated images with a numerical FM-AFM

• Fabien Castanié,
• Laurent Nony,
• Sébastien Gauthier and
• Xavier Bouju

Beilstein J. Nanotechnol. 2012, 3, 301–311, doi:10.3762/bjnano.3.34

• implemented with the n-AFM, advanced first-principles methods [92] are well adapted to deal with local changes of electronic structure when the tip interacts with the sample surface, especially for KPFM [93][94]. For weak chemical interactions and van der Waals forces, theoretical studies have demonstrated

• temperature). This effect could be related to the local constraints of the carbon rings in the buckled graphene sheet. Graphene nanoribbon edges In the recent literature in the graphene community, there is a vivid interest in graphene nanoribbons (GNR), because one may tune their electronic structure through

Junction formation of Cu₃BiS₃ investigated by Kelvin probe force microscopy and surface photovoltage measurements

• Fredy Mesa,
• William Chamorro,
• William Vallejo,
• Robert Baier,
• Thomas Dittrich,
• Alexander Grimm,
• Martha C. Lux-Steiner and
• Sascha Sadewasser

Beilstein J. Nanotechnol. 2012, 3, 277–284, doi:10.3762/bjnano.3.31

• layer was obtained by a detailed investigation of this surface by macroscopic spectrally resolved SPV (see next section). A special strength of KPFM is the possibility to obtain locally resolved work-function information, as displayed in Figure 2. Special attention can be devoted to the electronic

• structure of grain boundaries in these polycrystalline materials. For the NH3-etched Cu3BiS3 sample, only a weak correspondence can be observed between the topography (Figure 2a) and the work function (Figure 2i), indicating that the charge state at the grain boundaries is similar to that of the grain

Simultaneous current, force and dissipation measurements on the Si(111) 7×7 surface with an optimized qPlus AFM/STM technique

• Zsolt Majzik,
• Martin Setvín,
• Andreas Bettac,
• Albrecht Feltz,
• Vladimír Cháb and
• Pavel Jelínek

Beilstein J. Nanotechnol. 2012, 3, 249–259, doi:10.3762/bjnano.3.28

• electronic structure of the surface dangling-bond state [46]. The drop occurs close to the setpoint, at which the short-range force reaches the maxima. Our spectroscopic data agree very well with similar measurements by means of the beam-deflection method [21]. Additionally, we repeated the spectroscopy

• both experimental [18][47][48] and theoretical [49][50][51][52] attention in recent years. However, a general understanding of the dissipation mechanism is still lacking. Beside the electronic-structure effects [53][54] and adhesion hysteresis at the atomic scale [49][51], there is also a so called

A measurement of the hysteresis loop in force-spectroscopy curves using a tuning-fork atomic force microscope

• Manfred Lange,
• Dennis van Vörden and
• Rolf Möller

Beilstein J. Nanotechnol. 2012, 3, 207–212, doi:10.3762/bjnano.3.23

• ][14][15] and its adsorption geometry and binding mechanism is well-known on several surfaces. Furthermore the electronic structure and growth of PTCDA on the Ag/Si(111) √3 × √3 surface is well understood [10][16][17]. In the submonolayer range the PTCDA molecules grow on the Ag/Si(111) √3 × √3 surface

Quantitative multichannel NC-AFM data analysis of graphene growth on SiC(0001)

• Christian Held,
• Thomas Seyller and
• Roland Bennewitz

Beilstein J. Nanotechnol. 2012, 3, 179–185, doi:10.3762/bjnano.3.19

• SiC bilayer height never coincide with a change in contact potential. The interface layer introduced in Figure 3c has been reported as a graphitic layer covalently bound to the SiC substrate [4][16]. While its influence on the electronic structure and contact potential is under discussion, it has no

X-ray spectroscopy characterization of self-assembled monolayers of nitrile-substituted oligo(phenylene ethynylene)s with variable chain length

• Hicham Hamoudi,
• Ping Kao,
• Alexei Nefedov,
• David L. Allara and
• Michael Zharnikov

Beilstein J. Nanotechnol. 2012, 3, 12–24, doi:10.3762/bjnano.3.2

• SAMs. This suggests, in accordance with the S 2p spectrum for these SAMs (Figure 2), the presence of a certain amount of the physisorbed molecules at the SAM-ambient interface in the case of NC-OPE1/Au. NEXAFS spectroscopy NEXAFS spectroscopy samples the electronic structure of unoccupied molecular

• the molecular conformation in the target SAMs, a series of calculations with the quantum-chemistry program package StoBe (Stockholm-Berlin) [80] were carried out for the OPE3 and NC-OPE3 molecules. Note that StoBe is used to evaluate and analyze the electronic structure as well as spectroscopic and

Current-induced dynamics in carbon atomic contacts

• Jing-Tao Lü,
• Tue Gunst,
• Per Hedegård and
• Mads Brandbyge

Beilstein J. Nanotechnol. 2011, 2, 814–823, doi:10.3762/bjnano.2.90

• while the contacts are in place and current is flowing. Furthermore, it is far from being trivial to add additional gate potentials in order to modify the electronic structure and gain independent control of the bias voltage and current [3][9]. On the theoretical side, it is desirable to develop

• detailed in [34], and in order to keep the calculation simple and tractable, we modeled the electrodes by simply employing the Γ k-point in the transverse electrode direction. The electron–phonon coupling matrix (M) was calculated at zero bias, whereas we calculated the electronic structure at finite bias

• further assumed linear ω-dependent friction, Berry force (BP), constant nonconservative force (NC), and ignore the renormalization of the dynamical matrix. We model the effect of Vb as a shift of the equilibrium chemical potential, EF. In this way we can tune the electronic structure within the bias