Repozitorij Univerze v Novi Gorici

Iskanje po repozitoriju
A+ | A- | Pomoč | SLO | ENG

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju

Opcije:
  Ponastavi


101 - 110 / 119
Na začetekNa prejšnjo stran3456789101112Na naslednjo stranNa konec
101.
Characterization of Mg low-index surfaces by first-principles
Miha Gunde, 2017, magistrsko delo

Opis: In this work, three surfaces, namely, Mg(0001), Mg(10 ̄1 0) and Mg(11 ̄2 0) are investigated by means of Density Functional Theory and Generalized Gradient Approximation first-principle calculations. The surfaces have been characterized in terms of their interlayer distances, surface energies, Projected Density of States and Surface Core Level Shifts. Contrary to what was found in previous studies based on Density Functional Theory-Local Density Approximation, the use of Generalized Gradient Approximation exchange correlation functional unravels the oscillatory behavior of both interlayer distances and Surface Core Level Shifts of Mg(10 ̄1 0). Moreover, the Projected Density Of States of un-reconstructed Mg(11 ̄2 0) exhibit the typical quantisation of electronic levels associated to a 2D-confinement of a 3D nearly-free electron gas, as observed in nano-wires, and a Peierls instability along the unconfined direction. Different possible reconstructions on Mg(11 ̄2 0) have then been investigated. In particular, it is found that the surface energy of (2X1) and (3X1) reconstructions is almost degenerate and lower than the surface energy of the unreconstructed Mg(11 ̄2 0) surface. Because of the quasi-degeneracy of surface energies, Mg(11 ̄2 0) surface should be composed by a combination of all the quasi degenerate phases.
Ključne besede: Density Functional Theory, first-principle calculations, Mg surface, Surface Core-Level Shift, surface relaxation, surface reconstruction
Objavljeno v RUNG: 04.07.2017; Ogledov: 7242; Prenosov: 2116
.pdf Celotno besedilo (1,77 MB)

102.
Introduction to Electronic Properties and Dynamics of Organic Complexes as Self‐Assembled Monolayers
Maddalena Pedio, 2017, samostojni znanstveni sestavek ali poglavje v monografski publikaciji

Opis: Self‐assembled monolayers (SAMs) of organic‐conjugated transition metal complexes on surfaces is a focus of both device engineering and basic science, since it is a key factor in nearly all important aspects of device performances, including operation voltages, degradation, and efficiency. The huge amount of literature results related to the first monolayer, and reorganization and self‐assembling processes are due to the general accepted result that structural and chemical properties of the first monolayer are the key parameters for controlled thin film growth. Optical and magneto‐electronic properties are intimately connected, and the accurate determination of electronic levels, excitation, and relaxation dynamics is mandatory for the optimization of electronic, photovoltaic, and opto‐electronic devices. Quite a number of electronic states is generated by the interaction of light with complex organic molecules. Time‐resolved spectroscopies are a new investigation tool that gives the possibility of correctly addressing their origin and life time. Examples of prototypical systems are presented and discussed. We review on complementary techniques, trying to single out how different approaches are fundamental to fully characterize these complex systems.
Ključne besede: self‐assembled monolayer (SAM), surface structures molecular layers, nanotechnology, electronic properties, spectroscopies, time resolved
Objavljeno v RUNG: 12.06.2017; Ogledov: 5695; Prenosov: 210
.pdf Celotno besedilo (5,78 MB)

103.
Time- and angle-resolved photoemission spectroscopy with optimized high-harmonic pulses using frequency-doubled Ti:Sapphire lasers
Steffen Eich, Jurij Urbančič, 2014, izvirni znanstveni članek

Opis: Time- and angle-resolved photoemission spectroscopy (trARPES) using femtosecond extreme ultraviolet high harmonics has recently emerged as a powerful tool for investigating ultrafast quasiparticle dynamics in correlated-electron materials. However, the full potential of this approach has not yet been achieved because, to date, high harmonics generated by 800 nm wavelength Ti:Sapphire lasers required a trade-off between photon flux, energy and time resolution. Photoemission spectroscopy requires a quasi-monochromatic output, but dispersive optical elements that select a single harmonic can significantly reduce the photon flux and time resolution. Here we show that 400 nm driven high harmonic extreme-ultraviolet trARPES is superior to using 800 nm laser drivers since it eliminates the need for any spectral selection, thereby increasing photon flux and energy resolution to <150 meV while preserving excellent time resolution of about 30 fs.
Ključne besede: angle-resolved photoemission spectroscopy, ARPES, high harmonic generation, ultrafast surface science
Objavljeno v RUNG: 20.04.2017; Ogledov: 6418; Prenosov: 0
Gradivo ima več datotek! Več...

104.
Self-amplified photo-induced gap quenching in a correlated electron material
Mathias Stefan, Eich Steffen, Jurij Urbančič, 2016, izvirni znanstveni članek

Opis: Capturing the dynamic electronic band structure of a correlated material presents a powerful capability for uncovering the complex couplings between the electronic and structural degrees of freedom. When combined with ultrafast laser excitation, new phases of matter can result, since far-from-equilibrium excited states are instantaneously populated. Here, we elucidate a general relation between ultrafast non-equilibrium electron dynamics and the size of the characteristic energy gap in a correlated electron material. We show that carrier multiplication via impact ionization can be one of the most important processes in a gapped material, and that the speed of carrier multiplication critically depends on the size of the energy gap. In the case of the charge-density wave material 1T-TiSe 2 , our data indicate that carrier multiplication and gap dynamics mutually amplify each other, which explains—on a microscopic level—the extremely fast response of this material to ultrafast optical excitation. Self-amplified photo-induced gap quenching in a correlated electron material. Available from: https://www.researchgate.net/publication/308804379_Self-amplified_photo-induced_gap_quenching_in_a_correlated_electron_material [accessed Apr 20, 2017].
Ključne besede: high harmonic generation, charge-density wave material, 1T-TiSe2, non-equilibrium electron dynamics, ultrafast surface science
Objavljeno v RUNG: 20.04.2017; Ogledov: 6822; Prenosov: 0
Gradivo ima več datotek! Več...

105.
Nanobodies against surface biomarkers enable the analysis of tumor genetic heterogeneity in uveal melanoma Patient Derived Xenografts
Ronan Crepin, David Gentien, Angeline Duche, Audrey Rapinat, Cecile Reyes, Fariba Nemati, Gerald Massonnet, Didier Deacaudin, Selma Djander, Sandrine Moutel, Klervi Even Desrumeaux, Nathalie Cassoux, Sophie Piperno-Neumann, Sebastian Amigorena, Franck Perez, Sergio Roman-Roman, Ario De Marco, 2017, izvirni znanstveni članek

Opis: Monoclonal antibodies specific for biomarkers expressed on the surface of uveal melanoma (UM) cells would simplify the immune-capture and genomic characterization of heterogeneous tumor cells originated from patient derived xenografts (PDXs). Antibodies against four independent tumor antigens were isolated by panning a nanobody synthetic library. Such antibodies enabled flow-cytometry-based sorting of distinct cell sub-populations from UM PDXs and to analyze their genomic features. The complexity and specificity of the biochemical and genomic biomarker combinations mirrored the UM tumor polyclonality. The data showed that MUC18 is highly and universally displayed at the surface of UM cells with different genetic background and consequently represents a reliable pan-biomarker for their identification and purification. In contrast, the other three biomarkers were detected in very variable combinations in UM PDX cells. The availability of the identified nanobodies will be instrumental in developing clone-specific drug evaluation and rational clinical strategies based on accurate genomic profiling
Ključne besede: nanobodies, uveal melanoma, patient derived xenografts, MUC18, membrane surface biomarkers, panning, tumor polyclonality
Objavljeno v RUNG: 19.04.2017; Ogledov: 6579; Prenosov: 0
Gradivo ima več datotek! Več...

106.
107.
108.
109.
Formation of Hybrid Electronic States in FePc Chains Mediated by the Au(110) Surface
Maria Grazia Betti, Pierluigi Gargiani, Carlo Mariani, Stefano Turchini, Nicola Zema, Sara Fortuna, Arrigo Calzolari, Stefano Fabris, 2012, izvirni znanstveni članek

Opis: Iron–phthalocyanine (FePc) molecules deposited on the Au(110) surface self-organize in ordered chains driven by the reconstructed Au channels. The interaction process induces a rehybridization of the electronic states localized on the central metal atom, breaking the 4-fold symmetry of the molecular orbitals of the FePc molecules. The molecular adsorption is controlled by a symmetry-determined mixing between the electronic states of the Fe metal center and of the Au substrate, as deduced by photoemission and absorption spectroscopy exploiting light polarization. DFT calculations rationalize this mixing of the Fe and Au states on the basis of symmetry arguments. The calculated electronic structure reproduces the main experimental spectral features, which are associated to a distorted molecular structure displaying a trigonal bipyramidal geometry of the ligands around the metal center.
Ključne besede: phthalocyanine, Au(110), gold, surface, DFT, density functional theory, calculation, simulation
Objavljeno v RUNG: 13.10.2016; Ogledov: 6066; Prenosov: 0
Gradivo ima več datotek! Več...

110.
Structural phases of ordered FePc-nanochains self-assembled on Au(110)
Betti Maria Grazia, Pierluigi Gargiani, Carlo Mariani, Roberto Biagi, Jun Fujii, Giorgio Rossi, Andrea Resta, Stefano Fabris, Sara Fortuna, Xavier Torrelles, Manvendra Kumar, Maddalena Pedio, 2012, izvirni znanstveni članek

Opis: Iron-phthalocyanine molecules deposited on the Au(110) reconstructed channels assemble into one-dimensional molecular chains, whose spatial distribution evolves into different structural phases at increasing molecular density. The plasticity of the Au channels first induces an ordered phase with a 5×5 symmetry, followed by a second long-range ordered structure composed by denser chains with a 5×7 periodicity with respect to the bare Au surface, as observed in the low-energy electron-diffraction (LEED) and grazing incidence X-ray diffraction (GIXRD) patterns. The geometry of the FePc molecular assemblies in the Au nanorails is determined by scanning tunneling microscopy (STM). For the 5×7 phases, the GIXRD analysis identifies a “4-3” rows profile along the [001] direction in the Au surface and an on-top FePc adsorption site, further confirmed by density functional theory (DFT) calculations. The latter also reveals the electronic mixing of the interface states. The chain assembly is driven by the molecule–molecule interaction and the chains interact with the Au nanorails via the central metal atom, while the chain–chain distance in the different structural phases is primarily driven by the plasticity of the Au surface.
Ključne besede: STM, LEED, DFT, density functional theory, phthalocyanine, Au(110), gold, surface
Objavljeno v RUNG: 13.10.2016; Ogledov: 5822; Prenosov: 0
Gradivo ima več datotek! Več...

Iskanje izvedeno v 0.04 sek.
Na vrh