Music for Social Impact: An overview of context, policy and activity in four countries, Belgium, Colombia, Finland, and the UK

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Development of Graphene Atomic Mirrors for Neutral Helium Microscopy

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de la Materia Condensada. Fecha de lectura: 11-09-2017Esta tesis tiene embargado el acceso al texto completo hasta el 11-03-201

Ultrasmooth metal thin films on curved fused silica by laser polishing

The fabrication of atomically smooth metal films on supporting oxides is a quite demanding task, since most physical vapor deposition methods used on metals do not work properly on oxide substrates. Here, we report an alternative procedure, based on performing laser polishing of a fused silica substrate before depositing the metallic thin film. This reduces the RMS surface roughness of fused silica by ca. 33%, and increases the maximum grain size of the metallic film from 200 nm to 1200 nm. The method has been applied to a fused silica parabolic lens, which has been coated with a graphene-terminated Ru thin film. The reduction of surface roughness caused by laser polishing leads to the formation of ultrasmooth Ru thin films. Crystallinity and subnanometer roughness of the metal coating are demonstrated by the observation of He diffraction from a macroscopically curved surface.This work has been supported by the European Union, FP7, Grant no. 309672 and by the Spanish MINECO under projects MAT2015-65356-C3-3-R and MAT2015-65356-C3-1-R. D.F. acknowledges financial support from the Spanish MINECO, through the “María de Maeztu” Programme for Units of Excellence in R&D (MDM-2014-0377)

Quality of graphene on sapphire: Long-range order from helium diffraction versus lattice defects from Raman spectroscopy

We report a new method to produce high-quality, transparent graphene/sapphire samples, using Cu as a catalyst. The starting point is a high-quality graphene layer prepared by CVD on Cu(111)/AlO. Graphene on sapphire is obtained in situ by evaporation of the Cu film in UHV. He-diffraction, atomic force microscopy (AFM), Raman spectroscopy and optical transmission have been used to assess the quality of graphene in a metal free area. We used helium atom scattering as a sensitive probe of the crystallinity of the graphene on sapphire. The observation of high reflectivity and clear diffraction peaks demonstrates the presence of flat and homogeneous graphene domains over lateral scales of microns, consistent with the AFM results. Surprisingly, putting graphene on sapphire improves the quality of the He-diffraction spectra. Graphene forms a moiré pattern with a (11 × 11) periodicity, aligned with the (1 × 1) sapphire unit cell. The lattice constant of graphene on sapphire is a = (2.44 ± 0.02) Å. The phonon dispersion of the graphene flexural mode has been measured. This allowed the determination of the bending rigidity k = 0.61 ± 0.15 eV, and the graphene-sapphire coupling strength g = (5.8 ± 0.4) × 10 N m. The uniformity of the graphene has also been investigated by Raman mapping. Judging by the ratio of the 2D to G peaks, the quality of the graphene is not degraded by Cu removal. The high transparency (80%) measured in the visible range makes this system suitable for many applications that require hybrid properties commonly associated with metals (conductivity) and insulators (transparency). Our study shows that He-diffraction and Raman provide crucial information on quite different, complementary aspects of the same samples.This project was sponsored by the European Union, Seventh Framework Programme: Theme NMP.2012.1.4-3 Grant no. 309672. AMW and HKY acknowledge support from the Alexander von Humboldt Foundation, the Max Planck EPFL Center for Molecular Nanoscience and Technology as well as the Deutsche Forschungsgemeinschaft under CRC 1073. Additionally, a part of the research has been supported by the Spanish MINECO, under project MAT2012-37276-C03-01, and by Comunidad de Madrid, under project S2013/MIT-2740 (PHAMA_2.0-CM). S2013/MIT-2740/PHAMA_2.0-CMPeer reviewe