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

• exchange–correlation functionals to reproduce the correct magnitude of band gaps. The calculated band structure can be improved by including self-energy corrections. However, including such corrections basically just affects the distance between valence and correction band, the shape and k-point dependence

• DOS of the substituted polymers is compared with the DOS of the unsubstituted PTp. Interestingly enough, although there are some changes in the band structure, there is only a minor effect of the substituents on the band gap. The band gap of 1.19 eV for the unsubstituted polythiophene is changed to

• more than 1 eV. In order to analyze the reason for the rather similar band gaps, we compare in Figure 6 the band structures of the unsubstituted polymer PTp (Figure 6a) with the substituted polymers NH2PTp (Figure 6b) and NO2PTp (Figure 6c). The amino group does not change the band structure

Pure hydrogen low-temperature plasma exposure of HOPG and graphene: Graphane formation?

• Baran Eren,
• Dorothée Hug,
• Laurent Marot,
• Rémy Pawlak,
• Marcin Kisiel,
• Roland Steiner,
• Dominik M. Zumbühl and
• Ernst Meyer

Beilstein J. Nanotechnol. 2012, 3, 852–859, doi:10.3762/bjnano.3.96

• valence-band structure, which suggests double-sided hydrogenation. With the scanning tunneling microscopy technique, various atomic-scale charge-density patterns were observed, which may be associated with different C–H conformers. Hydrogen-LTP-exposed graphene on SiO2 has a Raman spectrum in which the D

• theoretical calculation of hydrogenated graphite from Allouche et al. [34], full hydrogenation of graphite results in a σ band structure very similar to diamond, an sp3 hybridized carbon allotrope [33][36]. From this point of view, we can claim that this UPS spectrum is the valence band spectrum of

• different possible C–H conformations of hydrogenated graphene layers. On the other hand, surface corrugation or point defects caused after LTP exposure also have a contribution to these patterns. Regarding its valence-band structure measured with UPS, hydrogen-LTP-exposed HOPG has similar features to cubic

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

• energy splitting of the fine structure in the L3–eg band. From Figure 3a, we can see that this value is 0, 0.44 and 0.82 eV, respectively, for SrTiO3, (Na,H)TiNTs and anatase. Krüger showed that the L3–eg peak splitting in TiO2 is a band-structure effect, which mainly reflects the connectivity of the

Channeling in helium ion microscopy: Mapping of crystal orientation

• Vasilisa Veligura,
• Gregor Hlawacek,
• Raoul van Gastel,
• Harold J. W. Zandvliet and
• Bene Poelsema

Beilstein J. Nanotechnol. 2012, 3, 501–506, doi:10.3762/bjnano.3.57

• specimen. A measurement of the energy of the backscattered helium atoms provides quantitative information on composition [3], and ionoluminescence gives access to electronic properties such as the band structure and the nature of color centers. Unfortunately, to date no experimental procedure has been

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

• 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

Investigation on structural, thermal, optical and sensing properties of meta-stable hexagonal MoO₃ nanocrystals of one dimensional structure

• Angamuthuraj Chithambararaj and
• Arumugam Chandra Bose

Beilstein J. Nanotechnol. 2011, 2, 585–592, doi:10.3762/bjnano.2.62

• transformation into a highly stable orthorhombic structure were confirmed by thermal studies. The optical band structure and ethanol vapor-sensing behavior were studied by means of diffuse reflectance spectroscopy (DRS) and fiber optics spectroscopy, respectively. To the best of our knowledge, this paper reports

Room temperature excitation spectroscopy of single quantum dots

• Christian Blum,
• Frank Schleifenbaum,
• Martijn Stopel,
• Sébastien Peter,
• Marcus Sackrow,
• Vinod Subramaniam and
• Alfred J. Meixner

Beilstein J. Nanotechnol. 2011, 2, 516–524, doi:10.3762/bjnano.2.56

• trapped in a dark state. Clearly, these drops to the background level are not related to narrow absorbance lines due to the band structure of the semiconductor quantum dots. In this case, drops in the recorded intensity would result in excitation wavelengths for which no emission can be recorded. The

Simple theoretical analysis of the photoemission from quantum confined effective mass superlattices of optoelectronic materials

• Debashis De,
• Sitangshu Bhattacharya,
• S. M. Adhikari,
• A. Kumar,
• P. K. Bose and
• K. P. Ghatak

Beilstein J. Nanotechnol. 2011, 2, 339–362, doi:10.3762/bjnano.2.40

• ], IV–VI [12] and HgTe/CdTe [13] SLs have also been experimentally realized. The IV–VI SLs shows new physical properties in comparison with the III–V SL owing to the peculiar band structure of the constituent materials [14]. The II–VI SLs are being used for optoelectronic operation in the blue [14

Schottky junction/ohmic contact behavior of a nanoporous TiO₂ thin film photoanode in contact with redox electrolyte solutions

• Masao Kaneko,
• Hirohito Ueno and
• Junichi Nemoto

Beilstein J. Nanotechnol. 2011, 2, 127–134, doi:10.3762/bjnano.2.15

• solution) negatively charged. As the result the band structure of the SC (both the valence band (VB) and the conduction band) is bent as shown in Figure 3. This curved portion of the band structure is called a space charge layer (also called a depletion layer, where electrons are depleted). Under this

• the VB. The electron and the hole form an exciton (excited electron–hole pair), which is usually short-lived and recombines if there is no driving force to separate them. However, when the band structure is bent as in Figure 3 for an n-SC, the hole can migrate towards the SC interface, and the

• are transported first to the fluorine-doped tin oxide (FTO, SnO2:F) conductive layer through TiO2 grain boundaries and then to the cathode reducing electron acceptor there (O2 in the present case). In a Schottky junction, under the conditions when the band structure is flat without any bending, the

Ultrafine metallic Fe nanoparticles: synthesis, structure and magnetism

• Olivier Margeat,
• Marc Respaud,
• Catherine Amiens,
• Pierre Lecante and
• Bruno Chaudret

Beilstein J. Nanotechnol. 2010, 1, 108–118, doi:10.3762/bjnano.1.13

• ferromagnetic metals [1][2][3][4]. More surprisingly, the study of small Rh NPs revealed a paramagnetic to ferromagnetic phase transition induced by size reduction for clusters containing less than 40 atoms [5]. Band structure calculations have investigated the role of size reduction and demonstrated that it

• [16]. For all these systems, the structure of the clusters and the influence of the substrate, which could both modify the electronic band structure, remain uncertain. This could explain the disparities observed in the experimental results. The theoretical investigations carried out so far were

• to the atomic polytetrahedral arrangement, in particular the presence of many non-equivalent Fe sites compared to the conventional α-Fe phase. Band structure calculations on cubic Fe phases show a shell dependent magnetic moment with quite large differences between the core and the surface [7][8][9

On the reticular construction concept of covalent organic frameworks

• Binit Lukose,
• Agnieszka Kuc,
• Johannes Frenzel and
• Thomas Heine

Beilstein J. Nanotechnol. 2010, 1, 60–70, doi:10.3762/bjnano.1.8

• second code, which can perform calculations using k-points, was used to calculate the electronic properties (band structure and density of states). Band gaps have been calculated as an additional stability indicator. While these quantities are typically strongly underestimated in standard LDA- and GGA