Search results for "synchrotron"
showing 10 items of 307 documents
Using photoelectron emission microscopy with hard-X-rays
2001
We present several successful test cases of using photoelectron emission microscopy (PEEM) for photon energy up to 25 keV. First, the full extended X-ray absorption fine structure analysis was implemented in areas as small as 100 mum(2) for transition-metal K edge absorption spectra and, therefore, demonstrated the feasibility of combining structural and chemical analysis with hard-X-ray absorption spectroscopy with high lateral resolution. We also show that PEEM can be used in a transmission (radiography) mode as an imaging detector for hard-X-ray, This approach again leads to the unprecedented 0.3 mum lateral resolution, particularly critical for the use of coherence-based phase contrast …
High-resolution far-infrared synchrotron FTIR spectroscopy and analysis of the ν 7 , ν 19 and ν 20 bands of trioxane
2022
Rovibrational bands spectra of three ν20, ν7 and ν19 bands of 1, 3, 5 – trioxane (H2CO)3 were recorded in the 50–650 cm−1 range using a long path absorption cell coupled to a high resolution Fourier transform spectrometer and synchrotron radiation at the AILES beamline of the SOLEIL synchrotron. More than 16 000 lines were assigned with a dRMS better than 0.17 × 10−3 cm−1. Two different formalisms (tensorial and Watson) were used to derive accurate rotational and quartic parameters for the three bands and for the first time, a precise determination of Coriolis parameter and q+ l−doubling constant for both ν20 and ν19 perpendicular bands was obtained. Last, each set of spectroscopic paramete…
High-resolution infrared spectroscopy and analysis of the v2=v4 bending dyad and v3 stretching fundamental of ruthenium tetroxide
2017
International audience; RuO4 is a heavy tetrahedral molecule which has practical uses for several industrial fields. Due to its chemicaltoxicity and the radiological impact of its 103 and 106 isotopologues, the possible remote sensing of this compound in theatmosphere has renewed interest in its spectroscopic properties. We investigate here for the first time at high resolutionthe bending dyad region in the far IR and the line intensities in the 3 stretching region. Firstly, new high resolutionFTIR spectra of the bending modes region in the far infrared have been recorded at room temperature, using a speciallyconstructed cell and an isotopically pure sample of 102RuO4. New assignments and e…
INTEGRAL serendipitous detection of the gamma-ray microquasar LS 5039
2006
LS 5039 is the only X-ray binary persistently detected at TeV energies by the Cherenkov HESS telescope. It is moreover a gamma-ray emitter in the GeV and possibly MeV energy ranges. To understand important aspects of jet physics, like the magnetic field content or particle acceleration, and emission processes, such as synchrotron and inverse Compton (IC), a complete modeling of the multiwavelength data is necessary. LS 5039 has been detected along almost all the electromagnetic spectrum thanks to several radio, infrared, optical and soft X-ray detections. However, hard X-ray detections above 20 keV have been so far elusive and/or doubtful, partly due to source confusion for the poor spatial…
Single crystal EXAFS at high pressure
2000
Abstract We present a new technique for structure characterization under high pressure conditions. The use of an undulator beam of the third-generation ESRF source of synchrotron radiation has enabled the first single crystal EXAFS experiments at high pressure using a diamond anvil cell as pressure generator. Taking advantage of the linear polarization of X-rays the technique becomes an orientation-selective probe of the local structure of materials. We describe the principle of the technique and some applications.
Combustion wave structure during the MoSi2 synthesis by Mechanically-Activated Self-propagating High-temperature Synthesis (MASHS): In situ time-reso…
2006
Abstract In situ synchrotron time-resolved X-ray diffraction experiments coupled with an infrared imaging camera have been used to reveal the combustion wave structure during the production of MoSi2 by Mechanically Activated Self-propagating High-temperature Synthesis (MASHS). The fast combustion front exhibits a form described as an ‘equilibrium structure’ where the chemical reaction is the sole major driving force. In the MASHS process, oxide-free interfaces between Mo and Si nanocrystallites enhance the reaction Mo+2Si→MoSi2. Exhaustive time-resolved investigations show a possible solid-state process in the first second of the reaction within the combustion front. If preheating is added,…
The complementary structural studies of the double metal cyanide type catalysts for the ring opening polymerization of the oxiranes
2016
Przeprowadzono badania strukturalne katalizatorów dimetalocyjankowych (DMC) z dwoma rodzajami ligandów organicznych. Zaproponowano wyjaśnienie etapów przebiegu krzywych otrzymanych metodą analizy termograwimetrycznej i różnicowej kalorymetrii skaningowej (TG/DSC) badanych katalizatorów. Wykazano obecność kilku stopni związania ligandów w kompleksach DMC. Na podstawie wyników badań z wykorzystaniem absorpcji rentgenowskiej (XAS) stwierdzono, że centrum aktywne katalizatora stanowi atom cynku. W bezpośrednim sąsiedztwie atomów Zn wykryto obecność atomów Cl, natomiast w najbliższych sferach koordynacyjnych atomu Zn nie wykryto atomów tlenu.
Microspectroscopy and spectromicroscopy with photoemission electron microscopy using a new kind of imaging energy filter
2001
The use of an imaging retarding field analyser attached to the FOCUS IS-PEEM is described. This kind of energy filter is a simple, powerful tool to obtain microspectra from areas of down to about 1 μm using (V)UV and X-ray excitation sources. First results of microspectroscopy measured by excitation with a laboratory as well as a synchrotron X-ray source are presented.
Material quality characterization of CdZnTe substrates for HgCdTe epitaxy
2006
Cd1−xZnxTe (CZT) substrates were studied to investigate their bulk and surface properties. Imperfections in CZT substrates affect the quality of Hg1−xCdxTe (MCT) epilayers deposited on them and play a role in limiting the performance of infrared (IR) focal plane arrays. CZT wafers were studied to investigate their bulk and surface properties. Transmission and surface x-ray diffraction techniques, utilizing both a conventional closed-tube x-ray source as well as a synchrotron radiation source, and IR transmission micro-spectroscopy, were used for bulk and surface investigation. Synchrotron radiation offers the capability to combine good spatial resolution and shorter exposure times than conv…
Synchrotron radiation multiple diffraction study of Al0.304Ga0.172In0.524As MOVPE grown onto InP(001)
1997
Synchrotron radiation multiple diffraction in Renninger scanning (RS) geometry is used to characterise an Al0.304Ga0.172In0.524 As hetero-epitaxial layer MOVPE grown onto InP(001). (006) RS data for bulk, InP substrate and the quaternary layer were obtained using a new experimental set-up on station 7.6 at the Daresbury synchrotron radiation source. Examination of the multiple diffraction peak profiles reveal the epitaxial layers to have a higher mosaic spread than the underlying substrate materials. Measurements of the layer parallel lattice parameter a∥ = 5.8755 ± 0.003 A, as deduced from the tetragonal distortion measured at the 6-beam case in the layer RS, agrees very well with that obt…