A5003551331- Advanced X-ray Imaging Techniques
- Astrophysical Phenomena and Observations
- X-ray Spectroscopy and Fluorescence Analysis
- Adaptive optics and wavefront sensing
- Semiconductor materials and devices
- Advanced Chemical Physics Studies
- Particle Detector Development and Performance
- Ion-surface interactions and analysis
- Advanced Surface Polishing Techniques
- Catalytic Processes in Materials Science
- Electron and X-Ray Spectroscopy Techniques
- Particle Accelerators and Free-Electron Lasers
- Semiconductor materials and interfaces
- High-pressure geophysics and materials
- Metal and Thin Film Mechanics
- Catalysis and Oxidation Reactions
- Laser-induced spectroscopy and plasma
- Laser Material Processing Techniques
- Integrated Circuits and Semiconductor Failure Analysis
- Catalysts for Methane Reforming
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- ZnO doping and properties
- nanoparticles nucleation surface interactions
- Advancements in Photolithography Techniques
University of Twente
2021-2025
Cosine (Netherlands)
2008-2017
Leiden University
2004-2010
European Synchrotron Radiation Facility
2004-2010
European Science Foundation
2005
Karlsruhe Institute of Technology
1999
We present the first structure determination by surface x-ray diffraction during restructuring of a model catalyst under reaction conditions, i.e., at high pressure and temperature, correlate with change in catalytic activity. have analyzed Pt(110) CO oxidation pressures up to 0.5 bar temperatures 625 K. Depending on ratio, we find three well-defined structures: namely, (i) bulk-terminated surface, (ii) thin, commensurate oxide, (iii) incommensurate oxide. The oxide only appears when both...
A versatile instrument for the in situ study of catalyst surfaces by surface x-ray diffraction and grazing incidence small angle scattering a 13 ml flow reactor combined with reaction product analysis mass spectrometry has been developed. The bridges so-called "pressure gap" "materials at same time, within one experimental setup. It allows preparation catalytically active single crystal is also equipped an evaporator deposition thin, pure metal films, necessary formation particles on oxide...
The oxidation of a vicinal Pd(553) surface has been studied from ultrahigh vacuum (UHV) to atmospheric oxygen pressures at elevated sample temperatures. investigation combines traditional electron based UHV techniques such as high resolution core level spectroscopy, low-energy diffraction, scanning tunneling microscopy with in situ x-ray and ab initio simulations. In this way, we show that the O atoms preferentially adsorb step edges below...
Using a combined experimental and theoretical approach, we show that thin RhO2 oxide film forms on Pt25Rh75(100) surface at elevated oxygen pressures temperatures prior to the bulk oxidation. By use of in situ x-ray diffraction under realistic CO oxidation reaction conditions, onset growth coincides with an increase CO2 production. During reaction, consumed is continuously re-grown by gas phase. Our results strongly suggest adsorbs metallic substrate but reacts O border between substrate....
Future large X-ray observatories in space will require mirrors with effective areas and long focal lengths to accomplish the proposed science. ESA programs for developing lightweight optics based on modules of silicon pore (SPO) slumped glass (SGO) were put place IXO mission (f=20m, r≈1m). To test such MPE PANTER facility has been upgraded / extended support from accommodate in-focus measurements modules. We describe extension first results obtained measuring SPO SGO during commissioning.
Ultrafast laser irradiation of metals can often be described theoretically with the two-temperature model. The energy exchange between excited electronic system and atomic one is governed by electron-phonon coupling parameter. depends on both, temperature. We analyze effect dependence parameter temperature in ruthenium, gold, palladium. It shown that induces nonlinear behavior, which a higher initial leads to faster equilibration. Analysis experimental measurements transient...
Hydrogen, crucial for the green energy transition, poses a challenge due to its tendency degrade surrounding wall materials. To harness hydrogen's potential, it is essential identify parameter(s) of materials that modulates hydrogen-material interaction. In recent publication, we have shown reduction (denitridation) transition metal (TM) nitrides in hydrogen radicals (H*) stops when their work function drops below threshold limit. this work, tailor complex TM oxide by tuning relative...
We performed the experimental and theoretical study of heating damaging ruthenium thin films induced by femtosecond laser irradiation. present results an optical pump-probe thermoreflectance experiment with rotating sample allowing to significantly reduce heat accumulation in irradiated spot. show evolution surface morphology from growth a heat-induced oxide layer at low intermediate fluences cracking grooving high fluences. Theoretical analysis our allows us relate behavior hot electrons...
Silicon Pore Optics, after 10 years of development, forms now the basis for future large (L) class astrophysics Xray observatories, such as ATHENA mission to study hot and energetic universe, matching L2 science theme recently selected by ESA launch in 2028. The scientific requirements result an optical design that demands high angular resolution (5") effective area (2 m<sup>2</sup> at a few keV) X-ray lens with focal length 12 to14 m. Optics was initially based on long (25 50 m) telescope...
Transition metal nitrides (TMNs) are reported as protective coatings in reactive hydrogen environments. Although the permeation of H2 through TMN is well reported, their reducibility H* environments less investigated. In this work, we categorize interaction with ambient exposed TiN, ZrN, HfN, VN, NbN, and TaN thin films at 700 °C into three classes. We find that TiN VN samples, H*-induced reduction was limited to surface (≈ top 2 nm). Significant denitridation observed ZrN HfN samples...
The Physikalisch-Technische Bundesanstalt (PTB) has used synchrotron radiation for the characterization of optics and detectors astrophysical X-ray telescopes more than 20 years. At a dedicated beamline at BESSY II, monochromatic pencil beam is by ESA cosine Research since end 2005 novel silicon pore optics, currently under development International Observatory (IXO). this beamline, photon energy 2.8 keV selected Si channel-cut monochromator. Two apertures distances 12.2 m 30.5 from dipole...
Silicon pore optics is a technology developed to enable future large area X-ray telescopes, such as the International Xray Observatory (IXO), candidate mission in ESA Space Science Programme 'Cosmic Visions 2015-2025'. IXO uses nested mirrors Wolter-I configuration focus grazing incidence photons on detector plane. The will have meet stringent performance requirements including an effective of ~3 m<sup>2</sup> at 1.25 keV and ~1 6 angular resolution better than 5 arc seconds. To achieve...
The science requirements for the Athena X-ray mirror are to provide a collecting area of 2 m<sup>2</sup> at 1 keV, an angular resolution ~5 arc seconds half energy eidth (HEW) and field view diameter 40-50 minutes. This combination over wide possible because unique features Silicon pore optics (SPO) technology used. Here we describe optimization modifications SPO required achieve specification demonstrate how optical design system impacts on scientific performance Athena.
Short-period multilayer mirrors are used in wavelength-dispersive x-ray fluorescence to extend the wavelength range available with naturally occurring Bragg-crystals. W/Si a period of 2.5 nm reflect and disperse elements O-Kα–Al-Kα range. However, reflectance is far from theoretical due nanoscale W-Si intermixing formation WSix. In this work, B4C diffusion barriers were applied sputter deposited multilayers inhibit W–Si interaction. A peak 45% at 9.7° grazing was measured 0.834 nm—the...
The electron-phonon coupling is the primary mechanism responsible for material relaxation after ultrafast laser irradiation. However, it remains an elusive variable that extremely challenging to extract experimentally, especially at high electron temperatures. Various previous theoretical approaches determine demonstrated large degree of inconsistency. In this paper, we present a first-principles framework simulating parameter based on spectral function, going beyond approximation introduced...
Future X-ray astrophysics missions, such as the International Observatory, IXO, require development of novel optics in order to deliver mission's large aperture, high angular resolution and low mass requirements. A series activities have been pursued by ESA, leading a consortium European industries develop Silicon Pore Optics for use an x-ray mirror technology. process takes base material commercially available silicon wafers, which shown possess excellent reflecting qualities. These are...
Silicon pore optics is a technology developed to enable future large area X-ray telescopes, such as the International Observatory (IXO) or Advanced Telescope for High ENergy Astrophysics (ATHENA), an L-class candidate mission in ESA Space Science Programme 'Cosmic Visions 2015-2025'. ATHENA/IXO use nested mirrors Wolter-I configuration focus grazing incidence photons on detector plane. The x-ray will have meet stringent performance requirements including effective of few m<sup>2</sup> at...
Silicon pore optics are currently under development for missions such as the International X-ray Observatory (IXO) an alternative to glass or nickel shell mirrors that were used in previous generation telescopes. The unprecedented effective area requirement of IXO requires a modular design suitable mass production. In this paper we discuss current state-of-the-art plate manufacturing technology. We provide examples process innovations have directly impacted cost per mirror and reduced...