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

• are based on density functional theory (DFT) using the SIESTA [27] code, and the PBE-GGA exchange-correlation [28] functional. We employ periodic boundary conditions (PBC) in the direction along the bend with a cell-width of four carbon dimers, and 10 Monkhorst–Pack k-points. We use a mesh cut-off of

• unit cells employed in this work [22][35][42][43]. Thus the adatom–adatom interaction will play a significant role in the kink-line propagation along the step and will be addressed in a future study. (a) Smooth ripple-like structure where the first and last six rows of carbon-dimers are surface-clamped

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

• monomers and dimers, they hardly influence the band gap of polythiophene. In contrast, phenyl-substituted polythiophenes as well as vinyl-bridged polythiophene derivatives exhibit drastically modified band gaps. These effects cannot be explained by simple electron removal or addition, as calculations for

• -based polymers, as it is known that there is a close relationship between the geometrical structure and the physical properties of conductive polymers [22]. As a starting point, we first considered thiophene monomers and dimers and then compared their properties to those of infinite chains of thiophene

• explicitly extended π-system influences the respective systems. Structural effects concerning bond lengths in the monomers and dimers compared to the unsubstituted Tp and BTp turned out to be negligibly small. Nevertheless, the dihedral angle between the two aromatic ring-systems in the substituted dimers

Characterization and properties of micro- and nanowires of controlled size, composition, and geometry fabricated by electrodeposition and ion-track technology

• Maria Eugenia Toimil-Molares

Beilstein J. Nanotechnol. 2012, 3, 860–883, doi:10.3762/bjnano.3.97

• 30 nm is demonstrated [127]. Figure 13 displays schematically the fabrication process (Figure 13a) and shows SEM images of Au nanowire dimers before (Figure 13b) and after (Figure 13c) silver dissolution. 4 Size-dependent properties Nanowires synthesized by electrodeposition in etched ion-track

Dimer/tetramer motifs determine amphiphilic hydrazine fibril structures on graphite

• Loji K. Thomas,
• Nadine Diek,
• Uwe Beginn and
• Michael Reichling

Beilstein J. Nanotechnol. 2012, 3, 658–666, doi:10.3762/bjnano.3.75

• elliptical features that are about 1.4 nm long (arrows in Figure 4d). Assuming that electron-rich delocalized π clouds of the aromatic rings dominate the image contrast [37], the bright blobs are interpreted as hydrogen-bonded dimers, as shown in Figure 4b. Note that the distance between adjacent bright

• respect to the aromatic rings to a minimum. One could construct a perfectly planar molecular layer of surface-filling molecules based on the described construction principles. However, zigzag structures result from defects introduced by dimers flipped by 180° around the fibril axis (shaded blue and green

Effect of the tip state during qPlus noncontact atomic force microscopy of Si(100) at 5 K: Probing the probe

• Adam Sweetman,
• Sam Jarvis,
• Rosanna Danza and
• Philip Moriarty

Beilstein J. Nanotechnol. 2012, 3, 25–32, doi:10.3762/bjnano.3.3

• excitation of silicon dimers, which is a key issue in scanning probe studies of Si(100). Conclusion: A wide range of novel imaging mechanisms are demonstrated on the Si(100) surface, which can only be explained by variations in the precise structural configuration at the apex of the tip. Such images provide

• ], and hence significantly complicate the interpretation of the acquired images. The silicon atoms terminating the Si(100) surface pair up into dimers in order to reduce the number of dangling bonds, and subsequently buckle, forming rows of alternately buckled dimers along the surface (Figure 1j). It has

• been shown that the structure of the rows may be locally manipulated by controlled tunnel-current injection [18], and we recently demonstrated that the buckling of the dimers can be toggled with atomic precision by direct application of mechanical force during NC-AFM [19][20]. In this paper we present

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

• current, allowing the dynamics to be followed down to single adatoms [13]. Electric current has been used to induce changes in graphene-edges, which were monitored while a current was simultaneously passed through the structure [14]. This was explained as carbon edge-dimers desorbing due to Joule-heating

Optical properties of fully conjugated cyclo[n]thiophenes – An experimental and theoretical approach

• Elena Mena-Osteritz,
• Fan Zhang,
• Günther Götz,
• Peter Reineker and
• Peter Bäuerle

Beilstein J. Nanotechnol. 2011, 2, 720–726, doi:10.3762/bjnano.2.78

• explained by the tendency of C10T to form dimers (excimers) in the excited state [29], which emit at lower energies with respect to the monomers (1.81 eV versus 2.18 eV). For the smallest cycle, C8T, we observe a weak structured emission band at much higher energy than the S0 ← S1 transition, whose origin

Self-organizing bioinspired oligothiophene–oligopeptide hybrids

• Alexey K. Shaytan,
• Eva-Kathrin Schillinger,
• Elena Mena-Osteritz,
• Sylvia Schmid,
• Pavel G. Khalatur,
• Peter Bäuerle and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2011, 2, 525–544, doi:10.3762/bjnano.2.57

• model of 1' (yellow box: Quaterthiophene backbone; green arrow: Peptide segment; blue coils: PEO chains). When forming dimers from molecules of 6' (kinked state), such as depicted in Figure 7b and c, an analog of hybrid 1' (referring to the arrangement of the peptide arms with respect to the conjugated

• backbones) is obtained. Thus, such dimers should mimic the single molecules of the corresponding disubstituted hybrid 1' with respect to the formation of inherently left-handed helical fibers (Figure 8, bottom panel). The driving forces for the formation of such proposed dimers could be the compensation of

• dipole moments of the single molecules in addition to a favorable intermolecular interaction of hydrophilic (peptide–PEO) and hydrophobic (quaterthiophene) parts of the molecules. Furthermore, the model revealed a separation of 8 Å between the quaterthiophene backbones of two adjacent dimers of 6', due

Septipyridines as conformationally controlled substitutes for inaccessible bis(terpyridine)-derived oligopyridines in two-dimensional self-assembly

• Daniel Caterbow,
• Daniela Künzel,
• Michael G. Mavros,
• Axel Groß,
• Katharina Landfester and
• Ulrich Ziener

Beilstein J. Nanotechnol. 2011, 2, 405–415, doi:10.3762/bjnano.2.46

• peripheral 3-pyridyl units point with both N-atoms in the opposite direction at the expense of attracting C–H…N interactions and forming a repulsive N...N interaction. An estimation of the interactions based on C–H…N double bond and single bond dimers [7] yields −36.5 kJ mol−1 for the conformation shown in