scholarly journals STEM in SEM For Medium-Resolution X-Ray Microanalysis

2009 ◽  
Vol 15 (S2) ◽  
pp. 474-475 ◽  
Author(s):  
PG Kotula
Keyword(s):  
X Ray ◽  
Medium Resolution

Extended abstract of a paper presented at Microscopy and Microanalysis 2009 in Richmond, Virginia, USA, July 26 – July 30, 2009

scholarly journals ESA’s X-Ray Astronomy Mission, XMM

1990 ◽  
Vol 123 ◽  
pp. 129-140
Author(s):  
B.G. Taylor ◽  
A. Peacock
Keyword(s):  
Resolving Power ◽  
Science Program ◽  
Eccentric Orbit ◽  
Ccd Cameras ◽  
Optical Telescope ◽  
X Ray ◽  
Medium Resolution ◽  
Reflection Gratings ◽  
Better Than

AbstractESA’s X-ray Astronomy Mission, XMM, scheduled for launch in 1998, is the second of four cornerstones of ESA’s long term science program Horizon 2000. Covering the range from about 0.1 to 10 keV, it will provide a high throughput of 5000 cm2 at 7 keV with three independant telescopes, and have a spatial resolution better than 30 arcsec. Broadband spectrophotometry is provided by CCD cameras while reflection gratings provide medium resolution spectroscopy (resolving power of about 400) in the range 0.3–3 keV. Long uninterrupted observations will be made from the 24 hr period, highly eccentric orbit, reaching a sensitivity approaching 10−15 erg cm−2 s−1 in one orbit. A 30 cm UV/optical telescope is bore-sighted with the x-ray telescopes to provide simultaneous optical counterparts to the numerous serendipitous X-ray sources which will be detected during every observation.

scholarly journals Binaries among the WN population in the Magellanic Clouds

2003 ◽  
Vol 212 ◽  
pp. 180-181
Author(s):  
Cédric Foellmi ◽  
Anthony F.J. Moffat ◽  
Martín A. Guerrero Roncel
Keyword(s):  
Radial Velocity ◽  
Magellanic Clouds ◽  
Photometric Data ◽  
Systematic Search ◽  
X Ray ◽  
Medium Resolution ◽  
Velocity Variations

We have undertaken a large and extensive spectroscopic survey of WNE stars both in the SMC and LMC with various 2m and 4m telescopes, reaching a total of 78 nights, spread over three years, and obtaining over 1500 long-slit spectra of medium resolution. The first goal is a systematic search for binaries via periodic radial-velocity variations. We enlarged our dataset with photometric data from the ogle and macho databases, and with archival X-ray data from the ROSAT and Chandra satellites.

Extreme X-ray beam compression for a high-resolution table-top grazing-incidence small-angle X-ray scattering setup

2013 ◽  
Vol 46 (6) ◽  
pp. 1544-1550 ◽  
Author(s):  
Matej Jergel ◽  
Peter Šiffalovič ◽  
Karol Végsö ◽  
Eva Majková ◽  
Dušan Korytár ◽  
...  
Keyword(s):  
High Resolution ◽  
Small Angle ◽  
Grazing Incidence ◽  
Photon Flux ◽  
X Ray ◽  
Space Resolution ◽  
X Ray Scattering ◽  
Medium Resolution ◽  
Beam Parameters ◽  
Ray Scattering

The application of V-shaped channel-cut GeSi(220) and Ge(220) monochromators for one-dimensional extreme X-ray beam compression was tested on a table-top setup for grazing-incidence small-angle X-ray scattering (GISAXS) with a microfocus source. A lattice constant gradient and different asymmetry angles of the diffractors were employed to enhance the compression factor to 21 and 15, respectively. It was demonstrated that the output beam parameters in terms of the size, divergence, photon flux and spectral bandwidth surpass those of the slit collimators used traditionally in GISAXS. A beam size far below 100 µm allows a high-resolution spatial GISAXS mapping, while the reciprocal space resolution of ∼500 nm approaches the level of synchrotron measurements and allows a fast one-shot detection of high-resolution GISAXS patterns. An oversampling shifts the detection limit up to ∼1 µm. The very short design of the compact high-resolution table-top GISAXS setup is another advantage of the extreme beam compression. Benefits of V-shaped monochromators for medium-resolution X-ray diffraction experiments as a bonus application are demonstrated by a comparison with parallel channel-cut monochromators combined with a slit.

Element-selective charge density visualization of endohedral metallofullerenes using synchrotron X-ray multi-wavelength anomalous powder diffraction data

2013 ◽  
Vol 46 (3) ◽  
pp. 649-655 ◽  
Author(s):  
Sachiko Maki ◽  
Eiji Nishibori ◽  
Daisuke Kawaguchi ◽  
Makoto Sakata ◽  
Masaki Takata ◽  
...  
Keyword(s):  
Charge Density ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Analysis ◽  
Entropy Method ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Density Maps ◽  
Medium Resolution ◽  
Multi Wavelength

An algorithm for determining the element-selective charge density has been developed using the maximum entropy method (MEM), Rietveld analysis and synchrotron X-ray multi-wavelength anomalous powder diffraction data. This article describes in detail both experimental and analytical aspects of the developed method. A structural study of yttrium mono-metallofullerene, Y@C82, 1:1 co-crystallized with toluene using the present technique is reported in order to demonstrate the applicability of the method even when only medium resolution data are available (d> 1.32 Å). Element-selective MEM charge density maps, computed from synchrotron X-ray powder diffraction data collected at three distinct wavelengths around the yttriumK-absorption edge (∼0.727 A), are employed for determining three crystallographic sites of the disordered yttrium.

scholarly journals Soft X-Ray Spectroscopy with Exosat

1984 ◽  
Vol 86 ◽  
pp. 59-66
Author(s):  
R. Mewe
Keyword(s):  
Absorption Edge ◽  
White Dwarf ◽  
White Dwarfs ◽  
Cataclysmic Variables ◽  
Atmospheric Model ◽  
Abundance Ratio ◽  
The Other ◽  
X Ray ◽  
Element Abundances ◽  
Medium Resolution

With the 500 and 1000 l/mm transmission gratings aboard the European x-ray Observatory SATellite (EXOSAT) we have measured medium-resolution (Δλ 5 A at 100 A) spectra of some ten objects of various categories such as isolated white dwarfs, cool stars with convective mantles, cataclysmic variables (e.g. AM Her) and a high-luminosity X-ray source (Sco X-1).The Instrument configuration was mostly such that one low-energy telescope was used as a photometer, while the other telescope was used as a spectrometer with the 500 l/mm grating inserted.The white dwarf spectra were measured between about 60 and 300 A. They show a continuum with no clear evidence of aborption and emission lines except for the He II absorption edge at 227 A in the spectrum of Feige 24. For the cooler (28 000 K) white dwarf Sirius B the emission is peaked between about 100 and 160 A and limited to about 200 A. which can be expected from atmospheric model spectra of DA white dwarfs. The soft X-ray emission of the hotter (> 60 000 K) DA white dwarfs (HZ43. Feige 24) is also interpreted in terms of photospheric emission. In the HZ43 spectrum the absorption edge is apparently absent which sets a stringent upper limit to the abundance ratio He/H of about 10−5. On the other hand the spectrum of Feige 24 shows a dominant absorption edge, implying He/H > 10−3. Moreover, here the shape of the continuum may be indicative of a stratification of element abundances in the outer atmosphere.

High and medium resolution spectroscopy of the X-ray transient 4U1543-47

1985 ◽  
Vol 40 (1-2) ◽  
pp. 207-212 ◽  
Author(s):  
L. Chiappetti ◽  
N.E. Whitel ◽  
S.M. Kahn ◽  
R. Shafer
Keyword(s):  
X Ray ◽  
Medium Resolution

scholarly journals On the perspectives of using XMM to study fundamental parameters of early-type stars

1999 ◽  
Vol 193 ◽  
pp. 90-91
Author(s):  
Gregor Rauw ◽  
Karel A. van der Hucht ◽  
Rolf Mewe ◽  
Manuel Güdel ◽  
Jean-Marie Vreux ◽  
...  
Keyword(s):  
Effective Area ◽  
Early Type ◽  
X Ray ◽  
Fundamental Parameters ◽  
Medium Resolution ◽  
Wide Range ◽  
Imaging Camera ◽  
Substantial Progress ◽  
Early Type Stars ◽  
Reflection Grating

Although substantial progress has been achieved since the discovery of X-ray emission from early-type stars with the EINSTEIN satellite, several crucial aspects of this phenomenon are still not fully understood. Considerable breakthroughs in this field are expected from observations with the X-ray Multi-Mirror satellite (XMM) due for launch in early 2000. XMM is the second cornerstone mission of the ESA Horizon 2000 science programme (see Lumb et al. 1996 and references therein for an overall description of the satellite). XMM offers a large effective area over a wide range of energies and its instrumentation provides simultaneously non-dispersive spectroscopic imaging (EPIC - European Photon Imaging Camera), medium-resolution dispersive spectroscopy (RGS - Reflection Grating Spectrometer) and optical-UV imaging (OM - Optical Monitor).

Towards high-flux X-ray beam compressing channel-cut monochromators

2016 ◽  
Vol 49 (6) ◽  
pp. 1885-1892 ◽  
Author(s):  
Karol Végsö ◽  
Matej Jergel ◽  
Peter Šiffalovič ◽  
Eva Majková ◽  
Dušan Korytár ◽  
...  
Keyword(s):  
Compression Ratio ◽  
Single Point ◽  
Grazing Incidence ◽  
High Flux ◽  
X Rays ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Medium Resolution ◽  
Experimental Resolution

The issue of a high-flux X-ray beam compressing channel-cut monochromator for applications in X-ray metrology is addressed. A Ge(111) compressor with compression ratio 20.3 was designed on the principle of a combination of symmetric and highly asymmetric diffractions. A pilot application of the single-point diamond technology (SPDT) to finish active surfaces of X-ray optics was tested, providing 50% flux enhancement as compared to a Ge(220) counterpart prepared by traditional surface treatment. This is much more than the theoretical 22% forecast and shows the potential of SPDT for preparation of high-flux X-ray compressors with a high compression ratio, where highly asymmetric diffraction with a very low exit angle is inevitable. The implications for efficient collection of X-rays from microfocus X-ray sources are discussed. A comparison of Ge compressors with Ge parallel channel-cut monochromators combined with a 50 µm slit shows the several times higher flux of the former, making them applicable in X-ray diffraction experiments at medium resolution. Furthermore, the Ge(111) compressor was tested as a collimator in high-resolution grazing-incidence small-angle X-ray scattering (GISAXS) measurements of surface gratings, providing experimental resolution close to 400 nm. This is ∼100 nm smaller than that achieved with the Ge(220) compressor but still approximately twice that of commercial SAXS/GISAXS laboratory setups.

High and Medium Resolution Spectroscopy of the X-Ray Transient 4U1543-47

1985 ◽  
pp. 207-212
Author(s):  
L. Chiappetti ◽  
N. E. White ◽  
S. M. Kahn ◽  
R. Shafer
Keyword(s):  
X Ray ◽  
Medium Resolution
Sign in / Sign up

Export Citation Format

Share Document