SwePub - sökning: WFRF:(Friedlein Rainer)

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1.	Crispin, Xavier, 1972-, et al. (författare) Electronic delocalization in discotic liquid crystals : A joint experimental and theoretical study 2004 Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 126:38, s. 11889-11899 Tidskriftsartikel (refereegranskat)abstract Discotic liquid crystals emerge as very attractive materials for organic-based (opto)electronics as they allow efficient charge and energy transport along self-organized molecular columns. Here, angle-resolved photoelectron spectroscopy (ARUPS) is used to investigate the electronic structure and supramolecular organization of the discotic molecule, hexakis(hexylthio)diquinoxalino[2,3-a:2′,3′-c]phenazine, deposited on graphite. The ARUPS data reveal significant changes in the electronic properties when going from disordered to columnar phases, the main feature being a decrease in ionization potential by 1.8 eV following the appearance of new electronic states at low binding energy. This evolution is rationalized by quantum-chemical calculations performed on model stacks containing from two to six molecules, which illustrate the formation of a quasi-band structure with Bloch-like orbitals delocalized over several molecules in the column. The ARUPS data also point to an energy dispersion of the upper π-bands in the columns by some 1.1 eV, therefore highlighting the strongly delocalized nature of the π-electrons along the discotic stacks.
2.	da Silva, DA, et al. (författare) Vibronic coupling in the ground and excited states of the naphthalene cation 2004 Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; :15, s. 1702-1703 Tidskriftsartikel (refereegranskat)abstract The hole - vibrational coupling in naphthalene is studied using high-resolution gas-phase photoelectron spectroscopy and density functional theory calculations (DFT), and a remarkable increase of the coupling with low-frequency vibrations is observed in the excited states.
3.	de Jong, Michel P, 1970-, et al. (författare) Orbital-specific dynamic charge transfer from Fe(II)-tetraphenylporphyrin molecules to molybdenum disulfide substrates 2005 Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 72:3, s. 35448- Tidskriftsartikel (refereegranskat)abstract Orbital-specific femtosecond charge transfer dynamics between Fe(II)-tetraphenylporphyrin molecules and semimetallic molybdenum disulfide substrates is investigated using core-level resonant photoemission spectroscopy. The electronic coupling to the substrate and the efficiency of charge transport across the interface is found to be different for the individual molecular electronic subsystems. In particular, electrons excited at the phenyl substituents are transferred within 3–6 fs, while hopping from the porphyrin ring is slower than 30 fs.
4.	de Jong, Michel P, et al. (författare) Ultraviolet photoelectron spectroscopy of polymers 2006 Ingår i: MOLECULAR CRYSTALS AND LIQUID CRYSTALS. - : Informa UK Limited. - 1542-1406 .- 1563-5287. ; 455, s. 193-203 Tidskriftsartikel (refereegranskat)abstract During the past three decades, ultraviolet photoelectron spectroscopy of polymer films has evolved from a sort of appearance-potential ( valence band edge) measurement, into a tool for studying the full valence band region of thin polymer films, including insulating polymers, semiconducting polymers and electrically conducting polymers. Progress may be loosely divided into several categories: (A) the melding of thin polymer film technology with ultra high vacuum technology and the widespread use of helium resonance lamps for studies of solid surfaces, (B) the combined approach of measurements and appropriate theoretical-computational methods, and (C) the advent of synchrotron radiation resulting in multi-photon spectroscopies, nominally in the area of the near UV. A coincident discovery of electrically conducting polymers, and especially the evolution of applications of semiconducting polymers, added technologically driven emphasis to this development of UPS for polymer materials. This contribution traces a limited number of highlights in the evolution of UPS of polymers, from the '70' s through to 2005.
5.	de Jong, Michel P, et al. (författare) Valence electronic states related to Mn2+ at La0.7 Sr0.3 MnO3 surfaces characterized by resonant photoemission 2006 Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 73:5 Tidskriftsartikel (refereegranskat)abstract Nonferromagnetic Mn2+ ions can be readily formed at the surface of half metallic La0.7 Sr0.3 MnO3 manganite as demonstrated by deoxygenating surface treatments. The 3 d5 contribution of these Mn2+ ions to the valence-band electronic structure has been characterized using Mn(2p) to 3d resonant photoemission measurements. The Mn2+ related 3d electrons were found to be stabilized by about 2 eV with respect to the mixed-valence 3d states, indicating their strong localization. Active participation of Mn2+ states in both spin and charge conductivity processes is therefore excluded. A two-channel picture, including independent Mn3+ Mn4+ and Mn2+ channels, emerges from detailed data analysis. Reversible Mn2+ formation and straightforward oxygen annealing effects point to a direct bonding between Mn2+ and oxygen vacancies that are most probably created at preexisting structural defects. The t2g and eg states of the mixed valence Mn3+ Mn4+ ions remain unaffected as the Mn2+ content increases, indicating a robust Mn3+ Mn4+ channel independent of structural defects. © 2006 The American Physical Society.
6.	Doherty, Walter J, et al. (författare) Electronic structure of Li-intercalated oligopyridines : A comparative study by photoelectron spectroscopy 2007 Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 126:9 Tidskriftsartikel (refereegranskat)abstract The role of nitrogen in the charge transfer and storage capacity of lithium-intercalated heterocyclic oligophenylenes was investigated using photoelectron spectroscopy. The development of new occupied states at low binding energies in the valence band region, as well as core level chemical shifts at both carbon and nitrogen sites, demonstrates partial charge transfer from lithium atoms to the organic component during formation of the intercalated compound. In small compounds, i.e., biphenyl and bipyridine derivatives, the position of the nitrogen heteroatom significantly affects the spacing between gap states in the Li-intercalated film, yet it has minimal effects on the charge storage capacity. In larger, branched systems, the presence of nitrogen in the aromatic system significantly enhances the charge storage capacity while the Li-N bond strength at high intercalation levels is significantly weakened relative to the nitrogen-free derivative. These observations have strong implications towards improved deintercalation processes in organic electrodes in lithium-ion batteries. © 2007 American Institute of Physics.
7.	Doherty, Walter J, et al. (författare) Layer-by-layer deposition of copper phthalocyanine from aqueous solution : Molecular orientation, ordering parameters, and electronic structure 2007 Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 111:6, s. 2724-2729 Tidskriftsartikel (refereegranskat)abstract Highly ordered, multilayer films composed of alternating, oppositely charged, polyionic copper phthalocyanines were prepared on HOPG [0001] substrates via layer-by-layer deposition from aqueous solution and characterized by scanning force microscopy and photoelectron spectroscopies. In films of up to four layers, individual layers alternate. Angle-resolved ultraviolet photoelectron spectra are consistent with a molecular orientation parallel to the substrate surface and indicate that structural order is reduced with film thickness © 2007 American Chemical Society.
8.	Friedlein, Rainer, et al. (författare) Electronic structure of conjugated polymers and interfaces in polymer-based electronics 2003 Ingår i: Synthetic Metals (Proceedings of the International Conference on Science and Technology of Synthetic Metals). - 0379-6779. ; 135:1-3, s. 275-277 Konferensbidrag (refereegranskat)abstract The electronic structure of conjugated polymers and interfaces in polymer-based electronics were analyzed. Fine structure were observed in the region of the first resonance with pi-final state symmetry, between 284.1 eV and 285.8 eV. The electronic transitions from the non-dispersed C(1s) level to specific parts of the unoccupied band structure were generated. It was found that for a dispersing valence band, in the presence of a core-hole, a given photon energy corresponded to an excitation into a state with a distinct wave vectors.
9.	Friedlein, Rainer, et al. (författare) Electronic structure of highly ordered films of self-assembled graphitic nanocolumns 2003 Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 68:19, s. 195414- Tidskriftsartikel (refereegranskat)abstract Highly ordered, several nanometers thick films of alkylated large planar, polycyclic aromatic hydrocarbon (PAH) molecules have been grown on semi-metallic molybdenum disulfide substrates. The films are characterized by a two-dimensional lateral arrangement of columns standing at the surface on a macroscopic scale. The self-assembly of such insulated columns of face-to-face disks with surface-induced vertical alignment has been achieved directly from solution processing. Angle-resolved photoelectron spectra revealed a highly anisotropic quasi-one-dimensional electronic structure with an extended π-electronic wave function. An intermolecular dispersion of the highest occupied band of at least 0.15 eV along the stacking direction has been measured. A partial breakdown of the concept of quasimomentum due to the finite size of the nano-objects perpendicular to the stacks is observed.
10.	Friedlein, Rainer, et al. (författare) High intercalation levels in lithium perylene stoichiometric compounds 2002 Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 354:5-6, s. 389-394 Tidskriftsartikel (refereegranskat)abstract Both amorphous and polycrystalline films of the aromatic hydrocarbon perylene are found to accept as high as one lithium per 3.3±0.1 carbon atoms. Phases composed of stoichiometric compounds with two, four and six lithium atoms per molecule are observed. The intercalation involves a substantial charge transfer from the lithium atoms to the molecules. Moreover, a high binding energy of the dopant-induced valence band electronic states is observed by photoelectron spectroscopy. Those observations suggest a high energy storage capacity for small- and medium-size aromatic hydrocarbons and their potential use in batteries. © 2002 Elsevier Science B.V. All rights reserved.
11.	Friedlein, Rainer, et al. (författare) Molecular parameters controlling the energy storage capability of lithium polyaromatic hydrocarbon intercalation compounds 2004 Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 129:1, s. 29-33 Tidskriftsartikel (refereegranskat)abstract One route for improving the performance of Li-based batteries is to optimize the carbon-based electrode. In order to find the best carbon-based materials, the specific roles of the molecular and solid-state contributions have to be understood. Here, the molecular contributions are analyzed. A semi-quantitative method is proposed to compare the charge storage capability of polyaromatic hydrocarbon molecules (PAHs). For planar PAHs, the ability to store electrical energy is found to be to a large extend determined by a single parameter, that is the electronic hardness (half the electronic gap) Multiplied the number of carbon atom in the molecule. A compilation of results for oligophenyls, oligoacenes and medium-size planar systems suggests trends in the dependence of the energy storage capability on the size and shape of the molecules. (C) 2003 Elsevier B.V. All rights reserved.
12.	Friedlein, Rainer, et al. (författare) Role of electronic localization and charge-vibrational coupling in resonant photoelectron spectra of polymers : Application to poly(para-phenylenevinylene) 2004 Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:12 Tidskriftsartikel (refereegranskat)abstract A combination of x-ray absorption and resonant photoemission (RPE) spectroscopy has been used to study the electronic structure of the one-dimensional conjugated polymer poly (para-phenylenevinylene) in nonordered (as prepared) thin films. The dispersion of RPE features for the decay to localized and delocalized bands are qualitatively different. A theory for band dispersion of RPE in polymers is given, showing the important roles of electronic state localization and vibrational (phonon) excitations for the character of the dispersion.
13.	Friedlein, Rainer, et al. (författare) Surface-induced vertical alignment of self-assembled supramolecular columns of large polycyclic aromatic hydrocarbons and porphyrins 2004 Ingår i: Synthetic metals. - : Elsevier BV. - 0379-6779 .- 1879-3290. ; 147:01-Mar, s. 79-83 Tidskriftsartikel (refereegranskat)abstract Ordered films of polycyclic aromatic hydrocarbons (PAHs) and porphyrins with functional (e.g. thiophene) side-groups are good candidates for (opto-)electronic applications where fast charge separation and transport are required. Such highly ordered thin films of PAHs, including discotic hexa-peri-hexabenzocoronene (HBC) and C-132-C-16,C-4, as well as brominated functionalized porphyrin molecules have been grown from solutions on semi-metallic molybdenum disulfide substrates and characterized by angle-resolved valence band photoelectron spectroscopy. A vertical growth of self-assembled supramolecular columns perpendicular to the basal plane of the substrate along with their lateral ordering on the surface has been achieved. Annealing made it possible to increase the structural order in the HBC columns, with molecules positioned at a regular offset from the columnar axis. This permitted the formation of extended pi-electronic states with a bandwidth of at least 0.1-0.2 eV at room temperature. (C) 2004 Elsevier B.V. All rights reserved.
14.	Friedlein, Rainer, et al. (författare) The role of intermolecular polarization for the stability of lithium intercalation compounds of a- and ß-perylene 2004 Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 121:5, s. 2239-2245 Tidskriftsartikel (refereegranskat)abstract The charge transfer in Li-intercalation compounds of the polyaromatic hydrocarbon perylene was examined. It was found that the valence and core-level photoelectron spectroscopies characterized the bonding configuration of the alkali metal atoms. The effect of intermolecular polarization on the ionization potential of Li atoms was compensated by a screening of the Madelung energy. The data collected illustrated that the large charge transfer in the a-perylene was due to the lower ionization potential of lithium atoms.
15.	J Doherty, Walter, et al. (författare) Selective hydrogen bond disruption in adenine monolayer films by reaction with water 2009 Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048. ; 174:1-3, s. 107-109 Tidskriftsartikel (refereegranskat)abstract High-resolution X-ray photoelectron spectroscopy of two-dimensional films of adenine on a highly oriented pyrolitic graphite [0 0 0 1] surface reveal bonding changes induced by exposure to water. The hydrogen-bond interactions between adenine molecules were replaced by adenine-water hydrogen bonds in a stepwise pattern. This reaction destroyed the film network and changed the chemical state of the nitrogen sites. The reaction with water molecules affected both the donor and acceptor states of the oxygen atoms, as compared to those in water. (C) 2009 Elsevier B.V. All rights reserved.
16.	Keil, M., et al. (författare) High levels of alkali-metal storage in thin films of hexa-peri-hexabenzocoronene 2002 Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 116:24, s. 10854-10860 Tidskriftsartikel (refereegranskat)abstract The results of the doping of molecular solid films of the medium-sized aromatic hydrocarbon hexa-peri-hexabenzocoronene (HBC), using lithium or sodium atoms were presented. The evolution of the valence band electronic structure was monitored by x-ray photoelectron spectroscopy and studied by ultraviolet photoelectron spectroscopy. Results indicated that n-doping depended on the type of alkali-metal atom employed and on the molecular order of the film. The smaller Li ion was found to have a stronger influence on the electronic structure than Na ions. These results revealed the potential use of the graphene materials in lithium-ion batteries with a high charge-storage capacity.
17.	Koch, N., et al. (författare) Molecular orientation dependent energy levels at interfaces with pentacene and pentacenequinone 2006 Ingår i: Organic electronics. - : Elsevier BV. - 1566-1199 .- 1878-5530. ; 7:6, s. 537-545 Tidskriftsartikel (refereegranskat)abstract We used ultraviolet photoelectron spectroscopy (UPS) to investigate the energy level alignment at contacts between pentacene and Ag(1 1 1) in the presence of interfacial 6,13-pentacenequinone (PQ). Depending on the metal pre-coverage with PQ, we found evidence for three distinctly different interface morphologies and molecular orientations, accompanied by significant changes of the energy level alignment. Consequently, the hole injection barrier between pentacene and Ag(1 1 1) varied between 1.1 eV (pristine Ag) and 0.45 eV (5.4 nm PQ pre-coverage on Ag). In addition, our UPS results suggest that PQ can act as deep trap for electrons in a pentacene matrix. Depending on the exact mutual orientation of PQ and pentacene, the depth of these traps can be in the range of 0.2-0.75 eV. © 2006 Elsevier B.V. All rights reserved.
18.	Kuritka, I., et al. (författare) Lithium intercalation of phenyl-capped aniline dimers : A study by photoelectron spectroscopy and quantum chemical calculations 2006 Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 110:38, s. 19023-19030 Tidskriftsartikel (refereegranskat)abstract Structural and electronic properties of pristine and lithium-intercalated, phenyl-capped aniline dimers as a model for the lithium-polyaniline system have been studied by photoelectron spectroscopy and quantum chemical calculations. It was found that the electronic structure of reduced and oxidized forms of oligoanilines is only weakly affected by isomerism. Upon intercalation, charge transfer from the Li-atoms is remarkable and highly localized at N-atomic sites, where configurations are energetically favored in which both N atoms of the dimers are bound to Li atoms. Conversion of nitrogen sites is different for the two forms of aniline dimers and incomplete up to high intercalation levels, indicating a pronounced role of solid-state effects in the formation of such compounds. © 2006 American Chemical Society.
19.	Luo, Yi, et al. (författare) A theoretical investigation of the near-edge X-ray absorption spectrum of hexa-peri-hexabenzocoronene 2001 Ingår i: Chemical Physics Letters. - 0009-2614 .- 1873-4448. ; 337:03-jan, s. 176-180 Tidskriftsartikel (refereegranskat)abstract The near-edge X-ray absorption spectrum of hexa-peri-hexabenzocoronene has been simulated by density functional theory techniques using transition state and full core hole potentials. The total spectrum is found to be a composition of multiple structure in the subspectra of the symmetry unique carbons, rather than by chemically shifted single pi* transitions. This quite 'fullerene-like' behavior, with only minor reminiscence of either graphite or benzene spectral features, is used to argue that long-range effects must be important to build up the dominating single excitonic pi* feature in graphite.
20.	Minkov, Ivaylo, et al. (författare) Core-excitations of biphenyl 2005 Ingår i: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 109:7, s. 1330-1336 Tidskriftsartikel (refereegranskat)abstract High-resolution C(1s) near-edge X-ray absorption and X-ray photoionization spectra of the free biphenyl molecule are presented and theoretically analyzed in order to allow an assignment of the observed spectral features. Finite lifetime broadening, a high density of vibrational states, and a strong overlap of contributions from chemically different carbon atom sites only partially allow resolving the vibrational fine structure. However, the shape and width of the spectral profiles are strongly determined by both chemical shifts and vibronic effects. In particular, different from photoionization of valence levels, both types of core level spectra do not contain contributions from dihedral modes which are related to the twisting motion of the two phenyl rings. Contrary to naphthalene, C-H stretching modes are significantly enhanced in the core excitation spectra of biphenyl while the contributions from C-C stretching modes are reduced.
21.	Minkov, Ivaylo, et al. (författare) Core-excitations of naphthalene : Vibrational structure versus chemical shifts 2004 Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 121:12, s. 5733-5739 Tidskriftsartikel (refereegranskat)abstract The initial state chemical shifts and vibrational fine structure of core excitations of naphthalene were analyzed using high-resolution x-ray photoelectron emission (XPS) and near-edge x-ray absorption fine structure (NEXAFS) spectra. The carbon atoms at peripheral sites were found to experience a small chemical shift and exhibit similar charge-vibrational coupling. The C-H stretching modes provide significant contributions to overall shape of spectra in the XPS spectra. The results show that vibrational fine structure dominates by particular C-C stretching modes, and in XPS of C2 and C3 sites also by high-energy C-H stretching modes.
22.	Oehzelt, M., et al. (författare) Crystallographic and morphological characterization of thin pentacene films on polycrystalline copper surfaces 2006 Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 124:5, s. 54711- Tidskriftsartikel (refereegranskat)abstract The degree of crystallinity, the structure and orientation of crystallites, and the morphology of thin pentacene films grown by vapor deposition in an ultrahigh vacuum environment on polycrystalline copper substrates have been investigated by x-ray diffraction and tapping-mode scanning force microscopy (TM-SFM). Depending on the substrate temperature during deposition, very different results are obtained: While at 77 K a long-range order is missing, the films become crystalline at elevated temperatures. From a high-resolution x-ray-diffraction profile analysis, the volume-weighted size of the crystallites perpendicular to the film surface could be determined. This size of the crystallites increases strongly upon changing temperature between room temperature and 333 K, at which point the size of individual crystallites typically exceeds 100 nm. In this temperature region, three different polymorphs are identified. The vast majority of crystallites have a fiber texture with the (001) net planes parallel to the substrate. In this geometry, the molecules are oriented standing up on the substrate (end-on arrangement). This alignment is remarkably different from that on single-crystalline metal surfaces, indicating that the growth is not epitaxial. Additionally, TM-SFM images show needlelike structures which suggest the presence of at least one additional orientation of crystallites (flat-on or edge-on). These results indicate that properties of thin crystalline pentacene films prepared on technologically relevant polycrystalline metal substrates for fast electronic applications may be compromised by the simultaneous presence of different local molecular aggregation states at all temperatures. © 2006 American Institute of Physics.
23.	Osikowicz, Wojciech, et al. (författare) A joint theoretical and experimental study on the electronic properties of phenyl-capped 3,4-ethylenedioxythiophene oligomers 2003 Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 119:19, s. 10415-10420 Tidskriftsartikel (refereegranskat)abstract The electronic structure of a series of phenyl-capped EDOT oligomers was studied using ultraviolet photoelectron spectroscopy, in combination with quantum-chemical methods. The bulk IP of the neutral PEDOT polymer was estimated to be 4.2 eV. The frontier band structue was predicted from the evolution of the spectral features in the studied series of oligomers.
24.	Osikowicz, Wojciech, 1974-, et al. (författare) Site-specific electronic structure of an oligo-ethylenedioxythiophene derivative probed by resonant photoemission 2005 Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 7 Tidskriftsartikel (refereegranskat)abstract A combination of conventional and resonant photoemission spectroscopy, x-ray absorption spectroscopy and ground-state quantum-chemical calculations has been used to study the valence electronic structure of a phenyl-capped 3,4-ethylenedioxythiophene oligomer, in polycrystalline thin films. The photon energy-dependent intensities of specific resonant decay channels are interpreted in terms of the spatial overlap of the excitation site and the ground-state molecular orbital involved in the decay. By making use of chemical shifts, excitations on different atomic sites are distinguished. It is demonstrated that site-specific information on the electronic structure of relatively large and complex organic systems may be obtained experimentally from non-radiative resonant decay spectra. In addition, these spectra provide relevant insight into the interpretation of near-edge x-ray absorption fine structure spectra. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
25.	Palermo, V., et al. (författare) Influence of molecular order on the local work function of nanographene architectures : A Kelvin-probe force microscopy study 2005 Ingår i: ChemPhysChem. - : Wiley. - 1439-4235 .- 1439-7641. ; 6:11, s. 2371-2375 Tidskriftsartikel (refereegranskat)abstract We report a Kelvin-probe force microscopy (KPFM) investigation on the structural and electronic properties of different submicronscale supramolecular architectures of a synthetic nanographene, including extended layers, percolated networks and broken patterm grown from solutions at surfaces. This study made it possible to determine the local work function (WF) of the different p-conjugated nanostructures adsorbed on mica with a resolution below 10 nm and 0.05 eV. It revealed that the WF strongly depends on the local molecular order at the surface, in particular on the delocalization of electrons in the p-states, on the molecular orientation at surfaces, on the molecular packing density, on the presence of defects in the film and on the different conformations of the aliphatic peripheral chains that might cover the conjugated core. These results were confirmed by comparing the KPFM-estimated local WF of layers supported on mica, where the molecules are preferentially packed edge-on on the substrate, with the ultraviolet photoelectron spectroscopy microscopically measured WF of layers adsorbed on graphite, where the molecules should tend to assemble face-on at the surface. It appears that local WF studies are of paramount importance for understanding the electronic properties of active organic nanostructures, being therefore fundamental for the building of high-performance organic electronic devices, including field-effect transistors, light-emitting diodes and solar cells. © 2005 Wiley-VCH Verlag GmbH & Co. KGaA.
26.	Samori, P., et al. (författare) Growth of ordered hexakis-dodecyl-hexabenzocoronene layers from solution : A SFM and ARUPS study 2001 Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1089-5647 .- 1520-6106 .- 1520-5207. ; 105:45, s. 11114-11119 Tidskriftsartikel (refereegranskat)abstract The layer growth of a polycyclic aromatic hydrocarbon moiety, hexakis-dodecyl-hexabenzocoronene (HBC-C12), from solution onto a conductive flat solid substrate has been studied. Scanning Force Microscopy (SFM), together with the analysis of the intensities of p-structures in spectra of Angle-Resolved Ultraviolet Photoelectron Spectroscopy (ARUPS) measurements, revealed that the HBC-C12 molecules can self-assemble as dry layers with the conjugated disklike molecules lying flat on the (0001) plane of highly oriented pyrolitic graphite (HOPG). By varying the rate of the molecular physisorption it was possible to orient these molecular architectures along preferential directions according to the symmetry of the substrate. Additionally, the film morphology is affected by the concentration of the solution. This indicates that the growth of these organic layers on HOPG is a kinetically governed process which, if carried out sufficiently slowly, leads to the growth of hetero-epitaxial crystallites.
27.	Sanchez-Carrera, R.S., et al. (författare) Vibronic coupling in the ground and excited states of oligoacene cations 2006 Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 110:38, s. 18904-18911 Tidskriftsartikel (refereegranskat)abstract The vibrational coupling in the ground and excited states of positively charged naphthalene, anthracene, tetracene, and pentacene molecules is studied on the basis of a joint experimental and theoretical study of ionization spectra using high-resolution gas-phase photoelectron spectroscopy and first-principles correlated quantum-mechanical calculations. Our theoretical and experimental results reveal that, while the main contribution to relaxation energy in the ground state of oligoacene systems comes from high-energy vibrations, the excited-state relaxation energies show a significant redistribution toward lower-frequency vibrations. A direct correlation is found between the nature of the vibronic interaction and the pattern of the electronic state structure. © 2006 American Chemical Society.
28.	Yamane, H., et al. (författare) Hole-vibration coupling in the uppermost valence band photoemission of pentacene monolayer on graphite 2006 Ingår i: MOLECULAR CRYSTALS AND LIQUID CRYSTALS. - : Informa UK Limited. - 1542-1406 .- 1563-5287. ; 455, s. 235-240 Tidskriftsartikel (refereegranskat)abstract The hole-vibration coupling of the highest occupied state in pentacene thin films on graphite was studied by high-resolution ultraviolet photoemission spectroscopy. It was found that vibration satellites in the film are more intense than that in the gas phase and the vibrational energy in the film is slightly lower than that in the gas phase. This demonstrates that the reorganization energy (hole mobility) in the pentacene thin film is slightly larger (smaller) than that expected from the photoemission spectrum of free pentacene molecules.
29.	Yamane, H., et al. (författare) Hole-vibration coupling of the highest occupied state in pentacene thin films 2005 Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 72:15 Tidskriftsartikel (refereegranskat)abstract The hole-vibration coupling of the highest occupied state in pentacene thin films on graphite is studied by high-resolution ultraviolet photoelectron spectroscopy. Vibration satellites in the film show a take-off-angle dependence, indicating that the Franck-Condon principle is not strictly satisfied in this system. They are more intense than in the gas phase and the vibrational energy in the film is slightly lower than that in the gas phase. This demonstrates that the reorganization energy in pentacene thin films is slightly larger than that estimated from the photoelectron spectrum of free pentacene molecules. Furthermore, it is pointed out that the electron hopping in the low-temperature film may occur in the femtosecond scale before the electronic polarization of the surrounding medium is completed. © 2005 The American Physical Society.
30.	Zhi, L., et al. (författare) Solid-state pyrolyses of metal phthalocyanines : A simple approach towards nitrogen-doped CNTs and metal/carbon nanocables 2005 Ingår i: Small. - : Wiley. - 1613-6810 .- 1613-6829. ; 1:8-9, s. 798-801 Tidskriftsartikel (refereegranskat)abstract Solid-state pyrolysis of organometallic precursors has emerged as an alternative method for preparing carbon nanostructures such as carbon nanotubes (CNT) and carbon anions. The morphology of the tubes can be controlled by the nature of the precursors and the pyrolysis procedures, and micrometer long nanotubes, composed of metal carbide wires encased in a graphitic sheath. Cobalt phthalocyanine (CoPc) as well as iron phthalocyanine were pyrolyzed at different temperatures to obtain CNTs. HRTEM and energy-dispersion X-Ray analysis disclosed that the core consisted of long, iron-containing single crystals and that the core was fully surrounded by crystallized graphic carbon. Iron-filled carbon nanotubes were also obtained from the pyrolysis of ferrocene by CVD method. Encapsulated iron carbide were also observed inside the carbon nanotubes formed after pyrolysis of FePc. These nanotubes and nanocables were considered useful for assembling miniaturized electronic device and sensors.

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