scholarly journals A new imaging technology based on Compton X-ray scattering

2021 ◽  
Vol 28 (5) ◽  
Author(s):  
Ángela Saá Hernández ◽  
Diego González-Díaz ◽  
Pablo Villanueva ◽  
Carlos Azevedo ◽  
Marcos Seoane
Keyword(s):  
Atmospheric Pressure ◽  
Solid Angle ◽  
Photon Counting ◽  
Sensitive Volume ◽  
3D Images ◽  
X Ray ◽  
X Ray Scattering ◽  
Custom Made ◽  
The Rose ◽  
Detector Design

A feasible implementation of a novel X-ray detector for highly energetic X-ray photons with a large solid angle coverage, optimal for the detection of Compton X-ray scattered photons, is described. The device consists of a 20 cm-thick sensitive volume filled with xenon at atmospheric pressure. When the Compton-scattered photons interact with the xenon, the released photoelectrons create clouds of secondary ionization, which are imaged using the electroluminescence produced in a custom-made multi-hole acrylic structure. Photon-by-photon counting can be achieved by processing the resulting image, taken in a continuous readout mode. Based on Geant4 simulations, by considering a realistic detector design and response, it is shown that photon rates up to at least 1011 photons s−1 on-sample (5 µm water-equivalent cell) can be processed, limited by the spatial diffusion of the photoelectrons in the gas. Illustratively, if making use of the Rose criterion and assuming the dose partitioning theorem, it is shown how such a detector would allow obtaining 3D images of 5 µm-size unstained cells in their native environment in about 24 h, with a resolution of 36 nm.

Temperature-gradient analyzers for non-resonant inelastic X-ray scattering

2021 ◽  
Vol 28 (3) ◽  
Author(s):  
Daisuke Ishikawa ◽  
Alfred Q. R. Baron
Keyword(s):  
Temperature Gradient ◽  
Solid Angle ◽  
Dispersion Compensation ◽  
Full Width ◽  
Half Maximum ◽  
Sensitive Detector ◽  
X Ray ◽  
X Ray Scattering ◽  
Position Sensitive ◽  
And Performance

The detailed fabrication and performance of the temperature-gradient analyzers that were simulated by Ishikawa & Baron [(2010). J. Synchrotron Rad. 17, 12–24] are described and extended to include both quadratic and 2D gradients. The application of a temperature gradient compensates for geometric contributions to the energy resolution while allowing collection of a large solid angle, ∼50 mrad × 50 mrad, of scattered radiation. In particular, when operating relatively close to backscattering, π/2 − θB = 1.58 mrad, the application of a gradient of 1.32 K per 80 mm improves the measured total resolution from 60 to 25 meV at the full width at half-maximum, while when operating further from backscattering, π/2 − θB = 6.56 mrad, improvement from 330 to 32 meV is observed using a combination of a gradient of 6.2 K per 80 mm and dispersion compensation with a position-sensitive detector. In both cases, the operating energy was 15.8 keV and the incident bandwidth was 22 meV. Notably, the use of a temperature gradient allows a relatively large clearance at the sample, permitting installation of more complicated sample environments.

scholarly journals Supercritical CO2extraction of porogen phase: An alternative route to nanoporous dielectrics

2004 ◽  
Vol 19 (11) ◽  
pp. 3224-3233 ◽  
Author(s):  
J.A. Lubguban ◽  
S. Gangopadhyay ◽  
B. Lahlouh ◽  
T. Rajagopalan ◽  
N. Biswas ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Selective Extraction ◽  
Porous Structures ◽  
Saxs Data ◽  
3D Images ◽  
X Ray ◽  
X Ray Scattering ◽  
Through Diffusion ◽  
Organosilicate Thin Films ◽  
Poly Propylene

We present a supercritical CO2(SCCO2) process for the preparation of nanoporous organosilicate thin films for ultralow dielectric constant materials. The porous structure was generated by SCCO2extraction of a sacrificial poly(propylene glycol) (PPG) from a nanohybrid film, where the nanoscopic domains of PPG porogen are entrapped within the crosslinked poly(methylsilsesquioxane) (PMSSQ) matrix. As a comparison, porous structures generated by both the usual thermal decomposition (at approximately 450 °C) and by a SCCO2process for 25 and 55 wt% porogen loadings were evaluated. It is found that the SCCO2process is effective in removing the porogen phase at relatively low temperatures (<200 °C) through diffusion of the supercritical fluid into the phase-separated nanohybrids and selective extraction of the porogen phase. Pore morphologies generated from the two methods are compared from representative three-dimensional (3D) images built from small-angle x-ray scattering (SAXS) data.

scholarly journals GISAXS studies of mesoporous films using a standard laboratory diffractometer

2014 ◽  
Vol 70 (a1) ◽  
pp. C883-C883
Author(s):  
Milen Gateshki ◽  
Alexander Kharchenko ◽  
Patricia Kidd
Keyword(s):  
Photon Counting ◽  
Grazing Incidence ◽  
Low Noise ◽  
Mesoporous Films ◽  
X Ray ◽  
Noise Characteristics ◽  
X Ray Scattering ◽  
Silica Thin Film ◽  
Sample Structure ◽  
Set Up

With the increasing number of GISAXS (Grazing-Incidence Small-Angle X-ray Scattering) applications for the investigation of materials surface nano-structures, comes the demand for a mainstream laboratory capability to run alongside the more established synchrotron facilities. GISAXS poses considerable challenges when scaling the method to fit a multipurpose laboratory instrument, including the achievement of good angular resolution at small scattering radius, the reduction of scatter from the direct beam and the observation of low intensity signals. We have developed a hardware solution that addresses these challenges. The recent availability of small size pixel (55 micron) photon counting detectors with very low noise characteristics has enabled the implementation of new 2D imaging GISAXS hardware for a standard 1.8KW laboratory X-ray source. In this work we present a number of results that illustrate the capabilities of the new experimental set-up based on a standard multipurpose diffractometer. We present GISAXS images and analysis of a mesoporous silica thin film with close-packed hexagonal type ordering of the pores. In [1] we have reported reflectometry results and analysis of this sample structure. The addition of GISAXS information demonstrates the versatility of the multipurpose diffractometer and the strength in combining methods on one instrument. Strongly scattering Ti-filled silica mesoporous films illustrate the relative ease with which GISAXS signals can be recorded, including even the weak signal below the critical angle of the sample (fig.1). The scattering patterns from both samples exhibit subtle departures from a simple symmetry, suggesting that the films may exhibit residual strain. Thin films with vertical mesopores provide their own challenges in the observation of scatter close and parallel to the specularly reflected beam. We present results in which scattering from Co-filled mesopore structures with 37nm pitch can be clearly resolved.

Application of X-Ray Scattering to the in Situ Study of Organometallic Vapor Phase Epitaxy

1988 ◽  
Vol 131 ◽  
Author(s):  
P. H. Fuoss ◽  
D. W. Kisker ◽  
S. Brennan ◽  
J. L. Kahn
Keyword(s):  
Vapor Phase ◽  
Atmospheric Pressure ◽  
Chemical Vapor ◽  
High Signal ◽  
X Ray ◽  
Surface Sensitivity ◽  
X Ray Scattering ◽  
Detailed Surface ◽  
Ray Scattering

ABSTRACTDespite their importance, the detailed surface reactions and rearrangements which occur during chemical vapor deposition remain largely undetermined because of the lack of suitable experimental probes. In principle, x-ray scattering and spectroscopy techniques are well suited to studying these near atmospheric pressure processes but advances in this area have been limited both by the lack of suitable x-ray sources and by the difficulty of integrating the growth and measurement experiments. We have developed equipment and techniques to perform in situ x-ray scattering studies of the structure of surfaces during organometallic vapor phase epitaxial (OMVPE) growth using the extremely bright undulator radiation from the PEP electron storage ring. In this paper, we describe our initial experimental results studying cleaning and subsequent reconstruction of GaAs (001) surfaces in a flowing H2 ambient. These results demonstrate the excellent surface sensitivity, low background and high signal levels necessary to study the dynamic processes associated with semiconductor growth using OMVPE.

scholarly journals MHz pump and probe combined with XAS-XES

2014 ◽  
Vol 70 (a1) ◽  
pp. C127-C127
Author(s):  
Pieter Glatzel
Keyword(s):  
Single Photon ◽  
Pulse Length ◽  
Photon Counting ◽  
European Synchrotron Radiation Facility ◽  
Theoretical Interpretation ◽  
X Rays ◽  
X Ray ◽  
X Ray Scattering ◽  
Pump And Probe ◽  
Ray Scattering

We implemented a MHz pump and probe scheme on beamline ID26 of the European Synchrotron Radiation Facility. The laser runs at 1.4 MHz in the ESRF 16b mode and thus pumps every fourth pulse with ca. 15 uJ per pulse and 350 fs pulse length. The beamline hosts an X-ray emission spectrometer and thus allows combining resonant inelastic X-ray scattering with a MHz pump and probe schemes. The scattered X-rays are recorded with an avalanche photodiode in single photon counting mode. We measured the transient spectra of the spin cross-over transition in [Fe(bpy)3]Cl2 of the non-resonant Ka lines and of 1s2p resonant inelastic X-ray scattering (RIXS) at the K absorption pre-edge of Fe. The Ka transient spectrum can be readily modeled using crystal field multiplet calculations because the spectra mainly depend on the Fe spin state. The 1s2p RIXS is richer in information because it also probes the unoccupied molecular orbitals and a theoretical interpretation is more challenging.

scholarly journals The modular small-angle X-ray scattering data correction sequence

2017 ◽  
Vol 50 (6) ◽  
pp. 1800-1811 ◽  
Author(s):  
B. R. Pauw ◽  
A. J. Smith ◽  
T. Snow ◽  
N. J. Terrill ◽  
A. F. Thünemann
Keyword(s):  
Small Angle ◽  
Direct Detection ◽  
Photon Counting ◽  
Scattering Data ◽  
X Ray ◽  
Data Correction ◽  
X Ray Scattering ◽  
Uncertainty Estimates ◽  
Wide Range ◽  
Ray Scattering

Data correction is probably the least favourite activity amongst users experimenting with small-angle X-ray scattering: if it is not done sufficiently well, this may become evident only during the data analysis stage, necessitating the repetition of the data corrections from scratch. A recommended comprehensive sequence of elementary data correction steps is presented here to alleviate the difficulties associated with data correction, both in the laboratory and at the synchrotron. When applied in the proposed order to the raw signals, the resulting absolute scattering cross section will provide a high degree of accuracy for a very wide range of samples, with its values accompanied by uncertainty estimates. The method can be applied without modification to any pinhole-collimated instruments with photon-counting direct-detection area detectors.

Accurate Calibration of Efficiencies of X-ray Detectors: Flow-Proportional and Scintillation Counters

1975 ◽  
Vol 29 (4) ◽  
pp. 316-322 ◽  
Author(s):  
T. C. Loomis ◽  
H. D. Keith
Keyword(s):  
Energy Range ◽  
Proportional Counter ◽  
Scintillation Counter ◽  
Photon Counting ◽  
Silicon Detector ◽  
Direct Methods ◽  
General Electric ◽  
Attenuation Coefficients ◽  
X Ray ◽  
X Ray Scattering

Direct methods have been devised for calibrating the quantum efficiencies of two x-ray detectors: a Siemens flow-proportional counter in the energy range 2.6 to 11.2 keV, and a General Electric SPG 5 scintillation counter in the range 5.9 to 50.4 keV. Literature values for x-ray attenuation coefficients of detector components are used only to estimate small corrections for x-ray scattering. The largest known errors in the measurements are statistical errors in photon counting and range from 0.03 to 0.23%. In the energy range 5.9 to 11.2 keV, efficiencies of a lithium-drifted silicon detector measured by comparison with the two calibrated detectors as references agree satisfactorily. Linear attenuation coefficients have been measured for argon, methane and P-10 gas (90% Ar; 10% CH4) in the energy range 2 to 12 keV; these can be used to calculate the efficiency of any flow-proportional counter of known geometry when used with counter gas consisting of a known mixture of argon and methane.

scholarly journals Versatile sample environments and automation for biological solution X-ray scattering experiments at the P12 beamline (PETRA III, DESY)

2015 ◽  
Vol 48 (2) ◽  
pp. 431-443 ◽  
Author(s):  
Clement E. Blanchet ◽  
Alessandro Spilotros ◽  
Frank Schwemmer ◽  
Melissa A. Graewert ◽  
Alexey Kikhney ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Screening ◽  
Photon Counting ◽  
Remote Access ◽  
High Throughput Analysis ◽  
Time Resolved ◽  
X Ray ◽  
Screening Experiments ◽  
X Ray Scattering ◽  
Ray Scattering

A high-brilliance synchrotron P12 beamline of the EMBL located at the PETRA III storage ring (DESY, Hamburg) is dedicated to biological small-angle X-ray scattering (SAXS) and has been designed and optimized for scattering experiments on macromolecular solutions. Scatterless slits reduce the parasitic scattering, a custom-designed miniature active beamstop ensures accurate data normalization and the photon-counting PILATUS 2M detector enables the background-free detection of weak scattering signals. The high flux and small beam size allow for rapid experiments with exposure time down to 30–50 ms covering the resolution range from about 300 to 0.5 nm. P12 possesses a versatile and flexible sample environment system that caters for the diverse experimental needs required to study macromolecular solutions. These include an in-vacuum capillary mode for standard batch sample analyses with robotic sample delivery and for continuous-flow in-line sample purification and characterization, as well as an in-air capillary time-resolved stopped-flow setup. A novel microfluidic centrifugal mixing device (SAXS disc) is developed for a high-throughput screening mode using sub-microlitre sample volumes. Automation is a key feature of P12; it is controlled by a beamline meta server, which coordinates and schedules experiments from either standard or nonstandard operational setups. The integrated SASFLOW pipeline automatically checks for consistency, and processes and analyses the data, providing near real-time assessments of overall parameters and the generation of low-resolution models within minutes of data collection. These advances, combined with a remote access option, allow for rapid high-throughput analysis, as well as time-resolved and screening experiments for novice and expert biological SAXS users.

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