34 research outputs found
Stability of the Surface Electron Accumulation Layers on the Nonpolar (1010) and (1120) Faces of ZnO
Enhanced hydrophobicity of CeO2 thin films: Role of the morphology, adsorbed species and crystallography
publishedVersio
Disentangling Electron-Boson Interactions on the Surface of a Familiar Ferromagnet
We report energy renormalizations from electron-phonon and electron-magnon
interactions in spin minority surface resonances on Ni(111). The different
interactions are disentangled and quantified in strength , based on
the characteristic shapes of their complex self-energies, and the largely
different binding energies at which they occur. The observed electron-magnon
interactions reveal a strong dependence on momentum and energy band position in
the bulk Brillouin zone. In contrast, electron-phonon interactions from the
same bands are observed to be practically momentum- and symmetry-independent.
Additionally, a moderately strong () electron-phonon interaction
is observed from a `buried', near-parabolic spin majority band that does not
cross the Fermi level.Comment: QuSpin 202
Controlling the growth of epitaxial graphene on metalized diamond (111) surface
The 2-dimensional transformation of the diamond (111) surface to graphene has been demonstrated using ultrathin Fe films that catalytically reduce the reaction temperature needed for the conversion of sp(3) to sp(2) carbon. An epitaxial system is formed, which involves the re-crystallization of carbon at the Fe/vacuum interface and that enables the controlled growth of monolayer and multilayer graphene films. In order to study the initial stages of single and multilayer graphene growth, real time monitoring of the system was preformed within a photoemission and low energy electron microscope. It was found that the initial graphene growth occurred at temperatures as low as 500 degrees C, whilst increasing the temperature to 560 degrees C was required to produce multi-layer graphene of high structural quality. Angle resolved photoelectron spectroscopy was used to study the electronic properties of the grown material, where a graphene-like energy momentum dispersion was observed. The Dirac point for the first layer is located at 2.5 eV below the Fermi level, indicating an n-type doping of the graphene due to substrate interactions, while that of the second graphene layer lies close to the Fermi level. (C) 2015 AIP Publishing LLC
Identifying chemical and physical changes in wide-gap semiconductors using real-time and near ambient-pressure XPS
Degradation of the chemotherapy drug 5-fouorouracil on medical-grade silver surfaces
The degradation of the chemotherapy drug 5-fluorouracil by a non-pristine metal surfaces is studied. Using density functional theory, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy we show that the drug is entirely degraded by medical-grade silver surfaces, already at body temperature, and that all of the fluorine has left the molecule, presumably as HF. Remarkably, this degradation is even more severe than that reported previously for 5-fluorouracil on a pristine monocrystalline silver surface (in which case 80% of the drug reacted at body temperature) [1]. We conclude that the observed reaction is due to a reaction pathway, driven by H to F attraction between molecules on the surface, which results in the direct formation of HF; a pathway which is favoured when competing pathways involving reactive Ag surface sites are made unavailable by environmental contamination. Our measurements indicate that realistically cleaned, non-pristine silver alloys, which are typically used in medical applications, can result in severe degradation of 5-fluorouracil, with the release of HF – a finding which may have important implications for the handling of chemotherapy drugs
Graphene coatings for chemotherapy: avoiding silver-mediated degradation
Chemotherapy treatment usually involves the delivery of fluorouracil (5-Fu) together with other drugs through central venous catheters. Catheters and their connectors are increasingly treated with silver or argentic alloys/compounds. Complications arising from broken catheters are common, leading to additional suffering for patients and increased medical costs. Here, we uncover a likely cause of such failure through a study of the surface chemistry relevant to chemotherapy drug delivery, i.e. between 5-Fu and silver. We show that silver catalytically decomposes 5-Fu, compromising the efficacy of the chemotherapy treatment. Furthermore, HF is released as a product, which will be damaging to both patient and catheter. We demonstrate that graphene surfaces inhibit this undesirable reaction and would offer superior performance as nanoscale coatings in cancer treatment applications