Search results for "synchrotron radiation"
showing 10 items of 146 documents
Fast elemental mapping and magnetic imaging with high lateral resolution using a novel photoemission microscope
1998
Abstract Using tunable soft X-ray synchrotron radiation and a new-generation photoemission electron microscope with integral sample stage and microarea selector, elemental images and local XANES spectra have been measured. Given the present conditions (PM3 at BESSY), the lateral resolution was in the range of 130 nm with the potential of considerable improvement with high-brilliance sources (a base resolution of 25 nm was obtained in threshold photoemission). Measurements at the oxygen K-edge demonstrate that differences in the local chemical environment of the emitter atom are clearly revealed and can thus be used as a fingerprint technique for its chemical state and geometrical surroundin…
Excitation processes of the blue luminescence in crystalline SiO 2 probed by synchrotron radiation measurements
2007
Luminescence properties of crystalline α-quartz were investigated by time-resolved spectroscopy under pulsed synchrotron radiation excitation in the vacuum ultraviolet range. Our results evidence that two emission bands overlap at 2.7 eV, both being observed only at low temperature. The first contribution is excited by band-to-band transition and is related to the radiative recombination of a self trapped exciton occurring in a time scale of a few ms, the second is associated with defects induced in quartz by γ- and β-radiation, is excited at 7.6 eV and its lifetime is 3.6 ns at T = 10 K. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Anomale röntgenstreuung zur erforschung makromolekularer strukturen
1982
The possibilities of anomalous X-ray scattering for the investigation of semi- or noncrystalline macromolecular structures are discussed on the grounds of the first successful measurements of anomalous scattering of iron in dissolved hemoglobin. As anomalous scattering of this kind of material is limited to the near vicinity of the X-ray absorption edges, the use of synchrotron radiation appears to be obligatory. The anomalous dispersion of the atomic form factors slightly increases with the atomic number. Anomalous dispersion is nearly doubled when going from the K-absorption edge to the LIII-absorption edge and from there to the Mv- absorption edge. Therefore, the use of anomalous dispers…
Luminescence and vacuum ultraviolet excitation spectroscopy of samarium doped SrB4O7
2020
Abstract Sm2+ and Sm3+ co-doped SrB4O7 could be utilized in several high-level optical devices and fundamental knowledge about the optical behavior of these materials benefits the development of luminescent applications. Herein, we report luminescence and its vacuum ultraviolet (VUV) excitation spectra in samarium doped SrB4O7. Both, Sm2+ and Sm3+ luminescence centers have been examined and distinguished in the emission and the excitation spectra investigated under synchrotron radiation. The contribution of either Sm2+ or Sm3+ emission lines into the emission spectra heavily depended on the excitation energy, and strong f-f transitions of both Sm2+ and Sm3+ were detected. At 10 K, a broad i…
Luminescence of γ-radiation-induced defects in α-quartz
2004
Optical transitions associated with γ-radiation-induced defects in crystalline α-quartz were investigated by photoluminescence excited by both pulsed synchrotron radiation and steady-state light. After a 10 MGy γ-dose we observed two emissions at 4.9 eV (ultraviolet band) and 2.7 eV (blue band) excitable in the range of the induced absorption band at 7.6 eV. These two luminescence bands show a different temperature dependence: the ultraviolet band becomes bright below 80 K; the blue band increases below 180 K, but drops down below 80 K. Both emissions decay in a timescale of a few ns under pulsed excitation, however the blue band could also be observed in slow recombination processes and it…
Nuclear Resonance Scattering Using Synchrotron Radiation (Mössbauer Spectroscopy in the Time Domain)
2010
Conventional Mossbauer spectroscopy (MS) can be considered as “spectroscopy in the energy domain.” It has been widely used since its discovery in 1958 [1]. Nuclear resonant forward scattering (NFS) of synchrotron radiation has been successfully employed as a time-differential technique since 1991 [2]. Another related technique, nuclear inelastic scattering (NIS) of synchrotron radiation [3], can be regarded as an extension of conventional, energy-resolved MS (in the range 10−9 to 10−7 eV) to energies on the order of molecular vibrations (in the range 10−3 to 10−1 eV). So far only a few “Mossbauer” stations for NFS and NIS measurements have become available in synchrotron laboratories, i.e.,…
Resonant X-Ray Scattering of Biological Systems
1987
Nearly all synchrotron radiation laboratories at high energy electron storage rings put enormous effort into the developement of resonant (anomalous) X-ray scattering techniques. So does the Hamburger Synchrotronstrahlungslabor (HASYLAB) at Hamburg. One of these intruments which is built in cooperation with the university of Mainz at the beam line A1 of the storage ring DORIS. How does the physics of resonant scattering enter into the design of the X-ray instrument.
Structure and Dynamics of Confined Liquids: Challenges and Perspectives for the X-ray Surface Forces Apparatus
2019
Preprint of the open access article Weiss, H., Cheng, H.-W., Mars, J., Li, H., Merola, C., Renner, F. U., Honkimäki, V., Valtiner, M., & Mezger, M. (2019). Structure and Dynamics of Confined Liquids: Challenges and Perspectives for the X-ray Surface Forces Apparatus. Langmuir, 35(51), 16679–16692. https://doi.org/10.1021/acs.langmuir.9b01215
Characterization of single semiconductor nanowires by synchrotron radiation nanoprobe
2012
In this work, we report on the results of the characterization of single semiconductor nanowires by x-ray fluorescence nanoprobe. Wurtzite InGaN and Co-implanted ZnO single nanowires were studied. Ternary semiconductor nanowires show an axial inhomogeneous elemental distribution, with Ga accumulating at the bottom and In at the top of the wires. The ZnO NWs, on the other hand, show a homogeneous distribution of the Co implanted along the nanowires, without signatures of clustering or segregation effects induced by the implantation. No signatures of unintentional doping are observed neither in the InGaN nor the ZnO NWs. These overall results demonstrate the suitability of X-ray fluorescence …
On-line tools for microscopic and macroscopic monitoring of microwave processing
2007
International audience; Direct monitoring of temperature, chemistry and microstructure is required to understand microwave heating in more detail, in order to fully exploit the unique features this non-equilibrium processing method can offer. In this paper, we show first that microwave radiometry can be used to follow volumetrically the thermal trajectory of microwave-heated aluminium powder. In-situ Raman spectroscopy is then shown to evidence thermal gradients between diamond and silicon grains in a binary powder mixture. Finally, perspectives and preliminary results of microstructural analysis obtained from X-ray microtomography are presented.