A5003883164- Hydrogen Storage and Materials
- Advanced Chemical Physics Studies
- Electron and X-Ray Spectroscopy Techniques
- Rare-earth and actinide compounds
- Diamond and Carbon-based Materials Research
- Surface and Thin Film Phenomena
- Carbon Nanotubes in Composites
- Nuclear Materials and Properties
- Graphene research and applications
- Force Microscopy Techniques and Applications
- Ammonia Synthesis and Nitrogen Reduction
- Magnetic Properties of Alloys
- Metal and Thin Film Mechanics
- Semiconductor materials and devices
- Ion-surface interactions and analysis
- Catalytic Processes in Materials Science
- Physics of Superconductivity and Magnetism
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Materials Characterization Techniques
- nanoparticles nucleation surface interactions
- Electrocatalysts for Energy Conversion
- Quantum, superfluid, helium dynamics
- Fusion materials and technologies
- Electronic and Structural Properties of Oxides
- X-ray Diffraction in Crystallography
University of Fribourg
1998-2024
ETH Zurich
1981-2024
Kyushu University
2016
National Institute for Materials Science
2009-2016
Swiss Federal Laboratories for Materials Science and Technology
2001-2010
Board of the Swiss Federal Institutes of Technology
1987-2008
École Polytechnique Fédérale de Lausanne
2007
Research Institute for Analytical Instrumentation
2003
Swiss Center for Electronics and Microtechnology (Switzerland)
2003
Hiroshima University
2002
The investigation of the field emission (FE) properties carbon nanotube (CNT) films by a scanning anode FE apparatus, reveals strong dependence on density and morphology CNT deposit. Large differences between microscopic macroscopic current site densities are observed, explained in terms variation enhancement factor β. As consequence, emitted can be optimized tuning CNTs. Films with medium (on order 107 emitters/cm2, according to electrostatic calculations) show highest densities.
The Fermi surface of ${\mathrm{Bi}}_{2}$${\mathrm{Sr}}_{2}$${\mathrm{CaCu}}_{2}$${\mathrm{O}}_{8+\mathit{x}}$(001) has been mapped at nearly 6000 points in k space using angle-resolved photoemission 300 K. We observe both features that are good agreement with the local density calculation Massidda, Yu, and Freeman [Physica (Amsterdam) 158C, 251 (1988)] others missing calculation. Among those missing, most importantly, we find a c(2\ifmmode\times\else\texttimes\fi{}2) superstructure on...
We have investigated the field emission properties of nanotube thin films deposited by a plasma enhanced chemical vapor deposition process from 2% CH4 in H2 atmosphere. Depending on metallic catalyst [Fe(NO3)3 an ethanol solution or sputtered Ni] showed nested continuous dense distribution tubes. The consisted multiwalled nanotubes (MWNTs) with diameters ranging 40 down to 5 nm, large fraction tubes having open ends. film emitters turn-on less than 2 V μm−1 for current 1 nA. An site density...
Photoemission studies combined with measurements of the magnetic susceptibility show that La segregates to surface La${\mathrm{Ni}}_{5}$ in presence ${\mathrm{O}}_{2}$ or ${\mathrm{H}}_{2}$O, and Ni precipitations are formed during hydrogenation. This represents a self-restoring mechanism active surface, since highly reactive removes oxygen keeps metallic. Dissociative adsorption ${\mathrm{H}}_{2}$ may then occur at atoms.
Nanostructured graphite was prepared by mechanical milling under hydrogen atmosphere. Several samples obtained after different times were systematically examined to get fundamental information about the structures and concentrations. After expansion of interlayer, long-range ordering interlayer disappears continuously with increasing time. The concentration reaches up 7.4 mass % (CH0.95) for 80 h. Judging from radial distribution function determined neutron diffraction measurement, there are...
Nanotube assemblies constrained to predetermined geometric patterns form the topic of research presented here (see also cover). It is demonstrated that microcontact printing can be used pattern silicon wafers with catalysts upon which multiwalled carbon nanotubes are selectively grown. The Figure a scanning electron microscopy image surface thus patterned nanotubes.
Phase pure nanotube films were grown on silicon substrates by a microwave plasma under conditions which normally are used for the growth of chemical vapor deposited diamond films. However, instead using any pretreatment leading to nucleation we metal clusters substrate. The resulting contain only nanotubes and also onion-like structures. no other carbon allotropes like graphite or amorphous clustered material could be found. adhere very well do not need further purification step. Electron...
The interaction of atomic hydrogen and low-energy ions with ${\mathrm{sp}}^{2}$-bonded carbon is investigated on the surfaces ${\mathrm{C}}_{60}$ multilayer films, single-walled nanotubes, graphite (0001). These three materials have been chosen to represent networks different local curvatures closed (i.e. no dangling bonds). Chemisorption these reduces emission from photoemission features associated \ensuremath{\pi} electrons leads a lowering work function up 1.3 eV. It found that energy...
We report on long-range electronic effects caused by hydrogen-carbon interaction at the graphite surface. Two types of defects could be distinguished with a combined mode scanning tunneling microscopy and atomic force microscopy: chemisorption hydrogen basal plane vacancy formation. Both show (sqrt[3]xsqrt[3])R30 degrees superlattice in local density states but have different topographic structure. The range modifications structure, fundamental importance for devices based carbon...
We present photoelectron spectroscopy investigations of in-situ prepared AgO. The sample was by room temperature oxidation Ag in an electron cyclotron resonance ${\mathrm{O}}_{2}$ plasma. In contrast to other measurements based on ex situ AgO powder samples, our show a distinct double peak structure the O $1s$ signal with remarkable chemical shift 2.9 eV between two components. These components can not be motivated from crystallographic point view as oxygen sites are all equivalent unit...