Note: This page contains sample records for the topic x-ray analysis electron from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

X-ray diffraction-based electronic structure calculations and experimental x-ray analysis for medical and materials applications  

Microsoft Academic Search

This thesis includes x-ray experiments for medical and materials applications and the use of x-ray diffraction data in a first-principles study of electronic structures and hyperfine properties of chemical and biological systems. Polycapillary focusing lenses were used to collect divergent x rays emitted from conventional x-ray tubes and redirect them to form an intense focused beam. These lenses are routinely

Dip Narayan Mahato

2009-01-01

2

X-ray diffraction-based electronic structure calculations and experimental x-ray analysis for medical and materials applications  

NASA Astrophysics Data System (ADS)

This thesis includes x-ray experiments for medical and materials applications and the use of x-ray diffraction data in a first-principles study of electronic structures and hyperfine properties of chemical and biological systems. Polycapillary focusing lenses were used to collect divergent x rays emitted from conventional x-ray tubes and redirect them to form an intense focused beam. These lenses are routinely used in microbeam x-ray fluorescence analysis. In this thesis, their potential application to powder diffraction and focused beam orthovoltage cancer therapy has been investigated. In conventional x-ray therapy, very high energy (˜ MeV) beams are used, partly to reduce the skin dose. For any divergent beam, the dose is necessarily highest at the entry point, and decays exponentially into the tissue. To reduce the skin dose, high energy beams, which have long absorption lengths, are employed, and rotated about the patient to enter from different angles. This necessitates large expensive specialized equipment. A focused beam could concentrate the dose within the patient. Since this is inherently skin dose sparing, lower energy photons could be employed. A primary concern in applying focused beams to therapy is whether the focus would be maintained despite Compton scattering within the tissue. To investigate this, transmission and focal spot sizes as a function of photon energy of two polycapillary focusing lenses were measured. The effects of tissue-equivalent phantoms of different thicknesses on the focal spot size were studied. Scatter fraction and depth dose were calculated. For powder diffraction, the polycapillary optics provide clean Gaussian peaks, which result in angular resolution that is much smaller than the peak width due to the beam convergence. Powder diffraction (also called coherent scatter) without optics can also be used to distinguish between tissue types that, because they have different nanoscale structures, scatter at different angles. Measurements were performed on the development of coherent scatter imaging to provide tissue type information in mammography. Atomic coordinates from x-ray diffraction data were used to study the nuclear quadrupole interactions and nature of molecular binding in DNA/RNA nucleobases and molecular solid BF3 systems.

Mahato, Dip Narayan

3

Surface elemental analysis in ambient atmosphere using electron-induced x-ray fluorescence  

Microsoft Academic Search

The progress in the development of the atmospheric electron x-ray spectrometer (AEXS) is described. The AEXS is a surface analysis tool based on excitation of characteristic x-ray fluorescence (XRF) spectra from samples in ambient atmospheres using a focused electron beam. Operation in ambient atmospheres with moderate-to-high spatial resolution in comparison to similar instruments is obtained through the use of a

Eduardo Urgiles; Risaku Toda; Jaroslava Z. Wilcox

2006-01-01

4

Calcium measurements with electron probe X-ray and electron energy loss analysis  

SciTech Connect

This paper presents a broad survey of the rationale for electron probe X-ray microanalysis (EPXMA) and the various methods for obtaining qualitative and quantitative information on the distribution and amount of elements, particularly calcium, in cryopreserved cells and tissues. Essential in an introductory consideration of microanalysis in biological cryosections is the physical basis for the instrumentation, fundamentals of X-ray spectrometry, and various analytical modes such as static probing and X-ray imaging. Some common artifacts are beam damage and contamination. Inherent pitfalls of energy dispersive X-ray systems include Si escape peaks, doublets, background, and detector calibration shifts. Quantitative calcium analysis of thin cryosections is carried out in real time using a multiple least squares fitting program on filtered X-ray spectra and normalizing the calcium peak to a portion of the continuum. Recent work includes the development of an X-ray imaging system where quantitative data can be retrieved off-line. The minimum detectable concentration of calcium in biological cryosections is approximately 300 mumole kg dry weight with a spatial resolution of approximately 100 A. The application of electron energy loss (EELS) techniques to the detection of calcium offers the potential for greater sensitivity and spatial resolution in measurement and imaging. Determination of mass thickness with EELS can facilitate accurate calculation of wet weight concentrations from frozen hydrated and freeze-dried specimens. Calcium has multiple effects on cell metabolism, membrane transport and permeability and, thus, on overall cell physiology or pathophysiology. Cells can be rapidly frozen for EPXMA during basal or altered functional conditions to delineate the location and amount of calcium within cells. 72 references.

LeFurgey, A.; Ingram, P. (Duke Univ., Durham, NC (USA))

1990-03-01

5

Simultaneous Detection of X-Ray Fluorescence and Conversion Electrons for Depth Selective XAFS Analysis  

SciTech Connect

An apparatus has been developed, which enables us to monitor both x-ray fluorescence yield (XFY) and conversion electron yield (CEY) from a sample. The apparatus has been installed to the BL11 of HSRC, and its basic performance has been evaluated. The detection limit of X-ray fluorescence analysis is 1.5 ppm for Ca and 6.6 ppm for S when the incident x-ray energy is optimized just above the absorption edge energy. The probing depth of the CEY method is estimated to be 4.0 nm for Ag thin films around Ag LIII edge while the escape depth of the x-ray fluorescence is more than 1 {mu}m The near surface sensitivity of the CEY is advantageous for XAFS measurements because x-ray fluorescence mode may suffer self-absorption-effects.

Hayakawa, Shinjiro; Makiyama, Yusuke; Esumi, Taku; Hirokawa, Takeshi [Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Hiroshima (Japan); Qiao, Shan; Namatame, Hirofumi [Hiroshima Synchrotron Radiation Center (HSRC), Hiroshima University, Hiroshima, (Japan); Morikawa, Atsushi; Tohno, Susumu [Graduate School of Energy Science, Kyoto University, Kyoto (Japan)

2007-02-02

6

Atmospheric electron x-ray spectrometer  

NASA Technical Reports Server (NTRS)

The present invention comprises an apparatus for performing in-situ elemental analyses of surfaces. The invention comprises an atmospheric electron x-ray spectrometer with an electron column which generates, accelerates, and focuses electrons in a column which is isolated from ambient pressure by a:thin, electron transparent membrane. After passing through the membrane, the electrons impinge on the sample in atmosphere to generate characteristic x-rays. An x-ray detector, shaping amplifier, and multi-channel analyzer are used for x-ray detection and signal analysis. By comparing the resultant data to known x-ray spectral signatures, the elemental composition of the surface can be determined.

Feldman, Jason E. (Inventor); George, Thomas (Inventor); Wilcox, Jaroslava Z. (Inventor)

2002-01-01

7

Elemental composition of bacterial metachromatic inclusions determined by electron microprobe X-ray analysis.  

PubMed Central

Electron microscopy and microprobe X-ray analysis were used to study metachromatic inclusions of Spirillum itersonii , Corynebacterium diphtheriae, and Micrococcus luteus. In situ metachromatic inclusions were electron dense and contained phosphorus and divalent cations. Metachromatic inclusions isolated by anion-exchange column chromatography and by isoosmolar Metrizamide density gradient centrifugation were similar in composition to in situ inclusions. Images

Webster, J A; Fay, D D; Costa, J L; Jones, P M; Hugh, R

1984-01-01

8

Calcium measurements with electron probe X-ray and electron energy loss analysis  

Microsoft Academic Search

This paper presents a broad survey of the rationale for electron probe X-ray microanalysis (EPXMA) and the various methods for obtaining qualitative and quantitative information on the distribution and amount of elements, particularly calcium, in cryopreserved cells and tissues. Essential in an introductory consideration of microanalysis in biological cryosections is the physical basis for the instrumentation, fundamentals of X-ray spectrometry,

A. LeFurgey; P. Ingram

1990-01-01

9

Calcium measurements with electron probe X-ray and electron energy loss analysis.  

PubMed

This paper presents a broad survey of the rationale for electron probe X-ray microanalysis (EPXMA) and the various methods for obtaining qualitative and quantitative information on the distribution and amount of elements, particularly calcium, in cryopreserved cells and tissues. Essential in an introductory consideration of microanalysis in biological cryosections is the physical basis for the instrumentation, fundamentals of X-ray spectrometry, and various analytical modes such as static probing and X-ray imaging. Some common artifacts are beam damage and contamination. Inherent pitfalls of energy dispersive X-ray systems include Si escape peaks, doublets, background, and detector calibration shifts. Quantitative calcium analysis of thin cryosections is carried out in real time using a multiple least squares fitting program on filtered X-ray spectra and normalizing the calcium peak to a portion of the continuum. Recent work includes the development of an X-ray imaging system where quantitative data can be retrieved off-line. The minimum detectable concentration of calcium in biological cryosections is approximately 300 mumole kg dry weight with a spatial resolution of approximately 100 A. The application of electron energy loss (EELS) techniques to the detection of calcium offers the potential for greater sensitivity and spatial resolution in measurement and imaging. Determination of mass thickness with EELS can facilitate accurate calculation of wet weight concentrations from frozen hydrated and freeze-dried specimens. Calcium has multiple effects on cell metabolism, membrane transport and permeability and, thus, on overall cell physiology or pathophysiology. Cells can be rapidly frozen for EPXMA during basal or altered functional conditions to delineate the location and amount of calcium within cells and the changes in location and concentration of cations or anions accompanying calcium redistribution. Recent experiments in our laboratory document that EPXMA in combination with other biochemical and electrophysiological techniques can be used to study, for example, sodium and calcium compartmentation in cultured cardiac cells. Such analyses can also be used to clarify the role of calcium in anoxic renal cell injury and to evaluate proposed ionic defects in cells of individuals with cystic fibrosis. PMID:2190819

LeFurgey, A; Ingram, P

1990-03-01

10

Calcium measurements with electron probe X-ray and electron energy loss analysis.  

PubMed Central

This paper presents a broad survey of the rationale for electron probe X-ray microanalysis (EPXMA) and the various methods for obtaining qualitative and quantitative information on the distribution and amount of elements, particularly calcium, in cryopreserved cells and tissues. Essential in an introductory consideration of microanalysis in biological cryosections is the physical basis for the instrumentation, fundamentals of X-ray spectrometry, and various analytical modes such as static probing and X-ray imaging. Some common artifacts are beam damage and contamination. Inherent pitfalls of energy dispersive X-ray systems include Si escape peaks, doublets, background, and detector calibration shifts. Quantitative calcium analysis of thin cryosections is carried out in real time using a multiple least squares fitting program on filtered X-ray spectra and normalizing the calcium peak to a portion of the continuum. Recent work includes the development of an X-ray imaging system where quantitative data can be retrieved off-line. The minimum detectable concentration of calcium in biological cryosections is approximately 300 mumole kg dry weight with a spatial resolution of approximately 100 A. The application of electron energy loss (EELS) techniques to the detection of calcium offers the potential for greater sensitivity and spatial resolution in measurement and imaging. Determination of mass thickness with EELS can facilitate accurate calculation of wet weight concentrations from frozen hydrated and freeze-dried specimens. Calcium has multiple effects on cell metabolism, membrane transport and permeability and, thus, on overall cell physiology or pathophysiology. Cells can be rapidly frozen for EPXMA during basal or altered functional conditions to delineate the location and amount of calcium within cells and the changes in location and concentration of cations or anions accompanying calcium redistribution. Recent experiments in our laboratory document that EPXMA in combination with other biochemical and electrophysiological techniques can be used to study, for example, sodium and calcium compartmentation in cultured cardiac cells. Such analyses can also be used to clarify the role of calcium in anoxic renal cell injury and to evaluate proposed ionic defects in cells of individuals with cystic fibrosis.

LeFurgey, A; Ingram, P

1990-01-01

11

Feasibility analysis for attosecond X-ray pulses at FERMI@ELETTRA free electron laser  

SciTech Connect

We present preliminary analysis for the feasibility of the attosecond x-ray pulses at a proposed FERMI@ELETTRA free electron laser (FEL) [1]. In part 1 we restrict ourselves to minimal modifications to the proposed FEL and consider a scheme for attosecond x-ray production which can be qualified as a small add-on to a primary facility. We demonstrate that at 5-nm wavelength our scheme is capable for production of pulses with an approximate duration of 100 attoseconds at approximately 2 MW peak power and with an absolute temporal synchronization to a pump laser pulse. In part 2 we propose to use an FEL amplifier seeded by a VUV signal and to follow it by the scheme for attosecond x-ray production described in part 1.

Zholents, Alexander

2004-09-01

12

X-ray analysis of a single aerosol particle with combination of scanning electron microscope and synchrotron radiation X-ray microscope  

NASA Astrophysics Data System (ADS)

We developed a microscope by a combination of synchrotron radiation X-ray fluorescence (SR-XRF) microscope and scanning electron microscope (SEM) with an energy dispersive X-ray spectrometer (EDX). SR-XRF is appropriate to detect trace and micro amount of elements and sensitive to heavy elements in an analyte but it cannot observe the real time image. SEM-EDX can observe the secondary electron image of a single particle in real time and is appropriate to detect lighter elements. This combination microscope can ensure the identification of the XRF spectrum to the SEM image without transferring the sample. For aerosol analysis, it is important to analyze each particle. The present method makes feasible to analyze not only the average elemental composition as the total particles but also elemental composition of each particle, which is dependent on the particle shape and size. The microscope was applied to an individual aerosol particle study. The X-ray spectra were different among the particles, but also different between SR-XRF and SEM-EDX for the same particle, due to the difference in fluorescence yields between X-ray excitation and electron excitation.

Toyoda, Masatoshi; Kaibuchi, Kazuki; Nagasono, Mitsuru; Terada, Yasuko; Tanabe, Teruo; Hayakawa, Shinjiro; Kawai, Jun

2004-08-01

13

Surface elemental analysis in ambient atmosphere using electron-induced x-ray fluorescence  

SciTech Connect

The progress in the development of the atmospheric electron x-ray spectrometer (AEXS) is described. The AEXS is a surface analysis tool based on excitation of characteristic x-ray fluorescence (XRF) spectra from samples in ambient atmospheres using a focused electron beam. Operation in ambient atmospheres with moderate-to-high spatial resolution in comparison to similar instruments is obtained through the use of a thin electron-transmissive membrane to isolate the vacuum of the electron probe, obviating the need for the samples to be drawn into the probe vacuum. Our initial setup that was used for the demonstration of the ability of the transmitted electrons to excite the XRF spectra in the external atmosphere consisted of an actively pumped chamber from within which the electrons were transmitted--not a portable instrument. The AEXS instrument that has been assembled in our laboratory during the past year consists of a miniature 20 keV electron microprobe that is vacuum sealed with a thin SiN membrane and requires no active pumping--a big step towards the development of a stand-alone instrument. The microprobe has been in operation for over one year and is used for performing rapid elemental analysis of NIST and USGS traceable metal and mineral standards, with good agreement with the certified composition for samples in up to about 90 Torr cm thick external atmospheres.

Urgiles, Eduardo; Toda, Risaku; Wilcox, Jaroslava Z. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)

2006-01-15

14

Electron Microprobe Analysis by Wavelength Dispersive X-ray Spectrometry (IAP 2006: Course 12.141) Course Notes  

Microsoft Academic Search

The electron microprobe provides a complete micron-scale quantitative chemical analysis of inorganic solids. The method is nondestructive and utilizes characteristic x-rays excited by an electron beam, incident on a flat surface of the sample. This course provides an introduction to the theory of x-ray microanalysis by wavelength and energy dispersive spectrometry (WDS and EDS), ZAF matrix correction procedures and different

Nilanjan Chatterjee

15

Comparison of synchrotron x-ray microanalysis with electron and proton microscopy for individual particle analysis  

SciTech Connect

This paper is concerned with the evaluation of the use of synchrotron/radiation induced x-ray fluorescences ({mu}-SRXRF) as implemented at two existing X-ray microprobes for the analysis of individual particles. As representative environmental particulates, National Institutes of Science and Technology (NIST) K227, K309, K441 and K961 glass microspheres were analyzed using two types of X-ray micro probes: the white light microprobe at beamline X26A of the monochromatic (15 keV) X-ray microprobe at station 7.6 of the SRS. For reference, the particles were also analyzed with microanalytical techniques more commonly employed for individual particles analysis such as EPMA and micro-PIXE.

Janssens, K.H.; van Langevelde, F.; Adams, F.C. [Universitaire Instelling Antwerpen, Antwerp (Belgium); Vis, R.D. [Vrije Univ., Amsterdam (Netherlands); Sutton, S.R.; Rivers, M.L. [Chicago Univ., IL (United States); Jones, K.W. [Brookhaven National Lab., Upton, NY (United States); Bowen, D.K. [Warwick Univ., Coventry (United Kingdom)

1991-12-31

16

Comparison of synchrotron x-ray microanalysis with electron and proton microscopy for individual particle analysis  

SciTech Connect

This paper is concerned with the evaluation of the use of synchrotron/radiation induced x-ray fluorescences ({mu}-SRXRF) as implemented at two existing X-ray microprobes for the analysis of individual particles. As representative environmental particulates, National Institutes of Science and Technology (NIST) K227, K309, K441 and K961 glass microspheres were analyzed using two types of X-ray micro probes: the white light microprobe at beamline X26A of the monochromatic (15 keV) X-ray microprobe at station 7.6 of the SRS. For reference, the particles were also analyzed with microanalytical techniques more commonly employed for individual particles analysis such as EPMA and micro-PIXE.

Janssens, K.H.; van Langevelde, F.; Adams, F.C. (Universitaire Instelling Antwerpen, Antwerp (Belgium)); Vis, R.D. (Vrije Univ., Amsterdam (Netherlands)); Sutton, S.R.; Rivers, M.L. (Chicago Univ., IL (United States)); Jones, K.W. (Brookhaven National Lab., Upton, NY (United States)); Bowen, D.K. (Warwick Univ., Coventry (United Kingdom))

1991-01-01

17

Use of Computers for X-Ray Absorption Edge, X-Ray Fluorescence, Electron Probe, and X-Ray Diffraction Analyses at Oak Ridge National Laboratory  

Microsoft Academic Search

Computers have been used by the X-Ray Analysis Section at Oak Ridge National Laboratory (ORNL) for several years. Codes are used for processing x-ray absorption edge, x-ray fluorescence, and electron probe data. A subroutine is available for plotting the x-ray fluorescence and electron probe data. The computer is also used to calculate lattice parameters from powder x-ray diffraction data.

H. W. Dunn

1972-01-01

18

Electron beam parallel X-ray generator  

NASA Technical Reports Server (NTRS)

Broad X ray source produces a highly collimated beam of low energy X rays - a beam with 2 to 5 arc minutes of divergence at energies between 1 and 6 keV in less than 5 feet. The X ray beam is generated by electron bombardment of a target from a large area electron gun.

Payne, P.

1967-01-01

19

Fast Detection Allows Analysis of the Electronic Structure of Metalloprotein by X-ray Emission Spectroscopy at Room Temperature  

PubMed Central

The paradigm of “detection-before-destruction” was tested for a metalloprotein complex exposed at room temperature to the high x-ray flux typical of third generation synchrotron sources. Following the progression of the x-ray induced damage by Mn K? x-ray emission spectroscopy, we demonstrated the feasibility of collecting room temperature data on the electronic structure of native Photosystem II, a trans-membrane metalloprotein complex containing a Mn4Ca cluster. The determined non-damaging observation timeframe (about 100 milliseconds using continuous monochromatic beam, deposited dose 1*107 photons/µm2 or 1.3*104 Gy, and 66 microseconds in pulsed mode using pink beam, deposited dose 4*107 photons/µm2 or 4.2*104 Gy) is sufficient for the analysis of this protein’s electron dynamics and catalytic mechanism at room temperature. Reported time frames are expected to be representative for other metalloproteins. The described instrumentation, based on the short working distance dispersive spectrometer, and experimental methodology is broadly applicable to time-resolved x-ray emission analysis at synchrotron and x-ray free-electron laser light sources.

Davis, Katherine M.; Mattern, Brian A.; Pacold, Joseph I.; Zakharova, Taisiya; Brewe, Dale; Kosheleva, Irina; Henning, Robert W.; Graber, Timothy J.; Heald, Steve M.; Seidler, Gerald T.; Pushkar, Yulia

2012-01-01

20

Distribution analysis of functional groups in polymers by derivatization-electron probe X-ray microanalysis  

Microsoft Academic Search

A new analytical method referred to as derivatization-electron probe X-ray microanalysis (XMA) has been developed to determine the distribution of 0.1% order functional groups in polymers with ?m level lateral resolution. The fundamental performance of XMA in analyzing derivatized polymers has been investigated. The results showed that the detection limit for the concentration of Br in a brominated epoxy resin

M Sugiura; A Murase; T Mitsuoka

2001-01-01

21

Distribution analysis of epoxy groups in polymers by derivatization-electron probe X-ray microanalysis.  

PubMed

An analytical method, referred to as "derivatization-electron probe X-ray micro-analysis (XMA)", has been developed to determine the distribution of a small amount of the functional groups in a polymer. The suitable conditions for the derivatization reaction with epoxy groups, which contribute to the hardening reactions of polymers, were investigated. It was found that epoxy groups in polymers were derivatized selectively using gas-phase esterification with hydrochloric acid (HCI). The most suitable amount of HCl in a 50 ml vial was 300 microl. After setting a sample in the vessel without directly contacting the reagent, by reacting the reagent and the sample at 25 degrees C for 1 h, the highest reaction yield and selectivity were obtained. By derivatization-XMA using this reaction condition, the measurement of the distribution of epoxy groups in the polymer became feasible. Actual applications to a depth analysis of epoxy groups in the hardened acrylic coating and epoxy resin proved that this method is useful for the characterization of polymers and for the study of the hardening reaction of polymers. PMID:11990569

Sugiura, M; Fukumoto, K; Murase, A; Ueda, K

2001-04-01

22

NASA Li\\/CF(x) cell problem analysis: Scanning electron microscopy with energy dispersive x ray spectrometry  

Microsoft Academic Search

An analysis was made of Lithium\\/carbon fluoride cell parts for possible chloride contamination induced by exposure to thionyl chloride (SOCl2); various samples were submitted for analysis. Only a portion of the analysis which has been conducted is covered, herein, namely analysis by scanning electron microscopy with energy dispersive x ray spectrometry (SEM\\/EDS). A strip of nickel was exposed to SOCl2

John Baker

1991-01-01

23

Comprehensive Study of Hydrated IDPs: X-Ray Diffraction, IR Spectroscopy and Electron Microscopic Analysis  

NASA Technical Reports Server (NTRS)

Chondritic hydrated interplanetary dust particles (IDPs) comprise up to 50% of all IDPs collected in the stratosphere(1). Although much is known about the mineralogy, chemistry and carbon abundance of hydrated IDPs (2-4) controversies still exist regarding their formation, history, and relationship to other primitive solar system materials. Hydrated IDPs are generally believed to be derived from asteroidal sources that have undergone some degree of aqueous alteration. However, the high C contents of hydrated IDPs (by 2 to 6X CI levels (3,4) indicate that they are probably not derived from the same parent bodies sampled by the known chondritic meteorites. We report the comprehensive study of individual hydrated IDPs. The strong depletion in Ca (I) has been used as a diagnostic feature of hydrated IDPs. The particles are embedded in elemental sulfur or low viscosity epoxy and ultramicrotomed thin sections are observed using a transmission electron microscope (TEM) equipped with an energy-dispersive X-ray detector (EDX) followed by other measurements including: 1) FTIR microspectroscopy to understand the significant constraints on the organic functionality and the nature of the C-bearing phases and 2) powder X-ray difiaction using a synchrotron X-ray source to understand the bulk mineralogy of the particles.

Nakamura, K.; Keller, L. P.; Nakamura, T.; Noguchi, T.; Nozaki, W.; Tomeoka, K.

2003-01-01

24

Effect of electrical charging on scanning electron microscopy-energy dispersive X-ray spectroscopy analysis of insulating materials  

NASA Astrophysics Data System (ADS)

We investigated the conditions under which we can obtain reasonable qualitative results in scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) analysis of trace elements in insulating materials using a diluted ionic liquid (EMI-CH3COO) and changing probe current. Below 100 nA, electrical charging of insulating materials was prevented. The probe current of 10 nA was suitable for qualitative analysis because the intensities of peaks from these materials were strong enough to detect trace elements at the concentration of 0.1 wt.% in the sample without interference by sum peaks. Diluted EMI-CH3COO can also be used for SEM-EDX quantitative analysis of insulating materials as discharging agents. In contrast, when insulating materials were electrically charged, the obtained spectra contained characteristic X-rays of the insulating materials with low energies and of materials other than the samples such as the sample stage and the collimator in the X-ray detector. This is because electrons from the electron beam were decelerated by and deflected from the insulating materials. By coating the insulating materials with the diluted EMI-CH3COO, the deceleration and deflection of the electron beam were prevented.

Imashuku, Susumu; Sakatoku, Shota; Kawai, Jun

2013-08-01

25

Stimulated electronic x-ray Raman scattering.  

PubMed

We demonstrate strong stimulated inelastic x-ray scattering by resonantly exciting a dense gas target of neon with femtosecond, high-intensity x-ray pulses from an x-ray free-electron laser (XFEL). A small number of lower energy XFEL seed photons drive an avalanche of stimulated resonant inelastic x-ray scattering processes that amplify the Raman scattering signal by several orders of magnitude until it reaches saturation. Despite the large overall spectral width, the internal spiky structure of the XFEL spectrum determines the energy resolution of the scattering process in a statistical sense. This is demonstrated by observing a stochastic line shift of the inelastically scattered x-ray radiation. In conjunction with statistical methods, XFELs can be used for stimulated resonant inelastic x-ray scattering, with spectral resolution smaller than the natural width of the core-excited, intermediate state. PMID:24476271

Weninger, Clemens; Purvis, Michael; Ryan, Duncan; London, Richard A; Bozek, John D; Bostedt, Christoph; Graf, Alexander; Brown, Gregory; Rocca, Jorge J; Rohringer, Nina

2013-12-01

26

Stimulated Electronic X-Ray Raman Scattering  

NASA Astrophysics Data System (ADS)

We demonstrate strong stimulated inelastic x-ray scattering by resonantly exciting a dense gas target of neon with femtosecond, high-intensity x-ray pulses from an x-ray free-electron laser (XFEL). A small number of lower energy XFEL seed photons drive an avalanche of stimulated resonant inelastic x-ray scattering processes that amplify the Raman scattering signal by several orders of magnitude until it reaches saturation. Despite the large overall spectral width, the internal spiky structure of the XFEL spectrum determines the energy resolution of the scattering process in a statistical sense. This is demonstrated by observing a stochastic line shift of the inelastically scattered x-ray radiation. In conjunction with statistical methods, XFELs can be used for stimulated resonant inelastic x-ray scattering, with spectral resolution smaller than the natural width of the core-excited, intermediate state.

Weninger, Clemens; Purvis, Michael; Ryan, Duncan; London, Richard A.; Bozek, John D.; Bostedt, Christoph; Graf, Alexander; Brown, Gregory; Rocca, Jorge J.; Rohringer, Nina

2013-12-01

27

X-ray free-electron lasers  

Microsoft Academic Search

With intensities 108–1010 times greater than other laboratory sources, X-ray free-electron lasers are currently opening up new frontiers across many areas of science. In this Review we describe how these unconventional lasers work, discuss the range of new sources being developed worldwide, and consider how such X-ray sources may develop over the coming years.

Neil R. Thompson; Brian W. J. McNeil

2010-01-01

28

Synchrotron radiation induced x-ray micro analysis: A realistic alternative for electron- and ion beam microscopy  

SciTech Connect

Synchrotron Radiation induced X-ray micro Fluorescence analysis ([mu]-SRXRF) is compared with more conventional microanalytical techniques such as Secondary Ion Microscopy (SIMS) and Electron Probe X-ray Microanalysis (EPXMA) for two typical microanalytical applications. SRXRF and EPXMA are employed for the analysis of individual particles, showing the complementary character of both techniques. By means of element mapping of trace constituents in a heterogeneous feldspar, the strong and weak points of SRXRF in comparison to EPXMA and SIMS are illustrated. The most striking difference between SRXRF and the other two microanalytical methods is the ability of SRXRF to probe deep into the investigated Material, whereas SIMS and EPXMA only investigate the upper surface of the material. The possibilities of SRXRF at third generation synchrotron rings is also briefly discussed.

Janssens, K.; Adams, F. (Universitaire Instelling Antwerpen, Antwerp (Belgium). Dept. of Chemistry); Rivers, M.L.; Jones, K.W. (Brookhaven National Lab., Upton, NY (United States))

1992-01-01

29

Synchrotron radiation induced x-ray micro analysis: A realistic alternative for electron- and ion beam microscopy?  

SciTech Connect

Synchrotron Radiation induced X-ray micro Fluorescence analysis ({mu}-SRXRF) is compared with more conventional microanalytical techniques such as Secondary Ion Microscopy (SIMS) and Electron Probe X-ray Microanalysis (EPXMA) for two typical microanalytical applications. SRXRF and EPXMA are employed for the analysis of individual particles, showing the complementary character of both techniques. By means of element mapping of trace constituents in a heterogeneous feldspar, the strong and weak points of SRXRF in comparison to EPXMA and SIMS are illustrated. The most striking difference between SRXRF and the other two microanalytical methods is the ability of SRXRF to probe deep into the investigated Material, whereas SIMS and EPXMA only investigate the upper surface of the material. The possibilities of SRXRF at third generation synchrotron rings is also briefly discussed.

Janssens, K.; Adams, F. [Universitaire Instelling Antwerpen, Antwerp (Belgium). Dept. of Chemistry; Rivers, M.L.; Jones, K.W. [Brookhaven National Lab., Upton, NY (United States)

1992-10-01

30

Semi-quantitative analysis of changes in soil coatings by scanning electron microscope and energy dispersive X-ray mapping  

Microsoft Academic Search

Scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDX) has been used extensively with soils and sediments. The method of obtaining X-ray spectrums at single points on samples has two shortcomings; (1) it is limited to a particular point and (2) it is primarily a qualitative measure indicating the presence or the absence of specific elements. The relative

Bashar M Alsmadi; Peter Fox

2001-01-01

31

Imaging ultrafast electronic motion by x-ray scattering  

NASA Astrophysics Data System (ADS)

Time-resolved ultrafast x-ray scattering is an emerging approach to probe the temporally evolving electronic charge distribution in real-space and in real-time. In this contribution, time-resolved ultrafast x-ray scattering from an electronic wave packet is presented. It is shown that the spatial and temporal correlations are imprinted in the scattering patterns, obtained by ultrafast x-ray scattering from an electronic wave packet, which deviate drastically from the notion that the instantaneous electronic density is the key quantity being probed. Furthermore, a detailed analysis of ultrafast x-ray scattering from a sample containing a mixture of non-stationary and stationary electrons along with the role of scattering interference between a non-stationary and several stationary electrons to the total scattering signal is discussed.

Dixit, Gopal; Santra, Robin

2014-04-01

32

Molecular and elemental characterisation of mineral particles by means of parallel micro-Raman spectrometry and Scanning Electron Microscopy\\/Energy Dispersive X-ray Analysis  

Microsoft Academic Search

The “fingerprinting” of a molecular structure obtained by micro-Raman spectroscopy (MRS) can be successfully complemented by means of X-ray spot analysis through the application of scanning electron microscopy equipped with an X-ray detector (SEM\\/EDX). The elemental composition revealed by SEM\\/EDX is essential for a correct interpretation of the collected Raman spectra. The results presented here illustrate how the two techniques

E. A. Stefaniak; A. Worobiec; S. Potgieter-Vermaak; A. Alsecz; S. Török; R. Van Grieken

2006-01-01

33

Bremsstrahlung X rays from Jovian auroral electrons  

NASA Astrophysics Data System (ADS)

In a recent paper by D. D. Barbosa, it is argued that electron bremsstrahlung is the most likely source of the auroral x-ray emissions that have been observed at Jupiter. Barbosa bases his argument on observational and theoretical studies of the production of secondary electrons in the Earth's aurora. It is argued here that Barbosa's interpretation is flawed because it ignors the constraint that the primary electron distribution parameters place on the parameters for the secondary electron distribution. As a result, Barbosa's postulated secondary electron fluxes are over three orders of magnitude greater than the theory of auroral electrons permits.

Waite, J. Hunter, Jr.

1991-09-01

34

Profile correction to electron temperature and enhancement factor in soft x-ray pulse-height-analysis measurements in tokamaks  

SciTech Connect

Because soft x-ray pulse-height-analysis (PHA) spectra contain chordal information, the electron temperature and the radiation intensity (enhancement factor) measurements do not represent the local values. Assuming that the profile Ansatz for the electron temperature and density is of the form n/sub eo/(1-(ra)/sup 2/)/sup ..cap alpha../ and kT/sub eo/(1--(ra)/sup 2/)/sup ..beta../, we obtain the correction factors for the electron temperature and the enhancement factor as a function of the profile coefficients ..cap alpha.. and ..beta.. and the energy at which the evaluation was made. The corrected values of the temperature are typically between 1 to 10% higher than the values derived from the raw chordal spectra. We also correct the measured radiation intensity for the profile effects. Finally, the spectrum distortion due to pulse pile-up effects is evaluated. A set of curves is given from which the distortion of the spectrum can be obtained, if the electron temperature, the Be or Al filter thickness, and the electronic parameters of the acquisition system are known. 7 refs., 23 figs.

Sesnic, S.; Diesso, M.; Hill, K.; Holland, A.; Pohl, F.

1988-04-01

35

X-ray induced electron emission  

Microsoft Academic Search

The development and use of a magnetic spectrograph for the measurement of X-ray induced electron emission is described. Results are presented for metal and dielectric targets ranging in atomic number from Z=6 to Z-82. Materials studied were lead, tantalum, copper, aluminum, magnesium, solar cell cover glass, silica cloth, thermal control paint, Kevlar, Mylar, and conducting\\/nonconducting epoxy. Direct measurement was made

C. A. Aeby

1982-01-01

36

X-ray induced electron emission  

NASA Astrophysics Data System (ADS)

The development and use of a magnetic spectrograph for the measurement of X-ray induced electron emission is described. Results are presented for metal and dielectric targets ranging in atomic number from Z=6 to Z-82. Materials studied were lead, tantalum, copper, aluminum, magnesium, solar cell cover glass, silica cloth, thermal control paint, Kevlar, Mylar, and conducting/nonconducting epoxy. Direct measurement was made of the quantum yield and energy distribution of electrons emitted at angles of 0 deg, 30 deg, 45 deg and 60 deg with respect to the surface normal of targets exposed to normal incidence filtered and unfiltered 50 kV bremsstrah lung X-rays. Experimental results are compared with previous measurements where possible, and with computer code predictions where predictive capability matches the measurement range. The experimental results corroborates the cos theta angular dependence predicted by simple theoretical models, particularly for medium and high Z materials. A trend toward isotropic emission distribution is noted for the lower Z materials. Compared to the measured results, the emission yields predicted by a commonly used analytical model are low by approximately a factor of 2 for the unfiltered X-ray spectrum.

Aeby, C. A.

1982-04-01

37

The continental component of a Pacific Marine aerosol: Identification by combined neutron activation analysis and scanning electron microscopy with X-ray analysis  

Microsoft Academic Search

The relative merits and sampling requirements of instrumental neutron activation analysis (INAA) and scanning electron microscopy\\u000a (SEM) with energy dispersive X-ray spectroscopy (EDS) analysis as applied to the continental component of marine aerosols\\u000a are discussed. When correlated with air mass information, the quantitative INAA data on the concentrations of 15 major and\\u000a minor elements in the continental dust fraction provides

F. K. Lepple; P. E. Wilkniss; D. J. Bressan; W. H. Cullen; G. W. Phillips; K. W. Marlow

1977-01-01

38

NASA Li/CF(x) cell problem analysis: Scanning electron microscopy with energy dispersive x ray spectrometry  

NASA Technical Reports Server (NTRS)

An analysis was made of Lithium/carbon fluoride cell parts for possible chloride contamination induced by exposure to thionyl chloride (SOCl2); various samples were submitted for analysis. Only a portion of the analysis which has been conducted is covered, herein, namely analysis by scanning electron microscopy with energy dispersive x ray spectrometry (SEM/EDS). A strip of nickel was exposed to SOCl2 vapors to observe variations in surface concentrations of sulfur and chlorine with time. By detecting chlorine one can not infer contamination by SOCl2 only that contamination is present. Six samples of stainless steel foil were analyzed for chlorine using EDS. Chlorine was not detected on background samples but was detected on the samples which had been handled including those which had been cleaned. Cell covers suspected of being contaminated while in storage and covers which were not exposed to the same storage conditions were analyzed for chlorine. Although no chlorine was found on the covers from cells, it was found on all stored covers. Results are presented with techniques shown for analysis and identification. Relevant photomicrographs are presented.

Baker, John

1991-01-01

39

Analysis of x-ray emission and electron dynamics in a capillary-guided laser wakefield accelerator  

NASA Astrophysics Data System (ADS)

The dynamics of electron acceleration driven by laser wakefield inside a 30.5 mm long dielectric capillary tube is analyzed using radiation emitted in the x-ray range. 3D particle-in-cell simulations, performed with parameters close to the experimental ones, show that in long plasmas, the accelerated electrons catch up and finally overrun the driving laser owing to a higher velocity of the electrons in the plasma. The electrons are then transversely scattered by the laser pulse, and penetrate the capillary wall where they generate bremsstrahlung radiation, modeled using geant4 simulations. The signature of bremsstrahlung radiation is detected using an x-ray camera, together with the betatron radiation emitted during electron acceleration in the plasma bubble. The reflection of betatron radiation from the inner capillary surface also accounts for a fraction of the observed signal on the x-ray camera. The simulation results are in agreement with the experimental ones and provide a detailed description of the electron and radiation properties, useful for the design of laser wakefield accelerators or radiation sources using long plasma media.

Ju, J.; Genoud, G.; Ferrari, H. E.; Dadoun, O.; Paradkar, B.; Svensson, K.; Wojda, F.; Burza, M.; Persson, A.; Lundh, O.; Andreev, N. E.; Wahlström, C.-G.; Cros, B.

2014-05-01

40

ANALYSIS OF PASSIVATED SURFACES FOR MASS SPECTROMETER INLET SYSTEMS BY AUGER ELECTRON AND X-RAY PHOTOELECTRON SPECTROSCOPY  

SciTech Connect

Stainless steel coupons approximately 0.5' in diameter and 0.125' thick were passivated with five different surface treatments and an untreated coupon was left as a control. These surface treatments are being explored for use in tritium storage containers. These coupons were made to allow surface analysis of the surface treatments using well-know surface analysis techniques. Depth profiles using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) were performed on these coupons to characterize the surface and near surface regions. Scanning electron microscope (SEM) images were collected as well. All of the surface treatments studied here appear to change the surface morphology dramatically, as evidenced by lack of tool marks on the treated samples. In terms of the passivation treatment, Vendors A-D appeared to have oxide layers that were very similar in thickness to each other (0.7-0.9 nm thick) as well as the untreated samples (the untreated sample oxide layers appeared to be somewhat larger). Vendor E's silicon coating appears to be on the order of 200 nm thick.

Ajo, H.; Clark, E.

2010-09-01

41

X-ray Free-electron Lasers  

SciTech Connect

We review the present status and properties of X-ray free-electron lasers in operation or under construction in the nanometer and sub-nanometer wavelength range, and the novel possibilities they offer for the study of atomic and molecular processes. We also discuss recent developments in relativistic electron beam physics that give us the possibility of designing a new generation of X-ray free-electron lasers that: a. are more compact; b. reduce the radiation pulse duration to one femtosecond or below; c. extend the photon energy to the 50 keV region. These results are obtained by reducing the electron bunch charge while at same time maximizing the beam brightness and reducing the bunch length to a value near or smaller than the free-electron laser cooperation length. In the last case the radiation pulse is fully coherent in the longitudinal and transverse space. The increase in beam brightness can also be used to reduce the beam energy needed for a given radiation wavelength, when, at the same time, the undulator period is reduced. The simultaneous decrease in beam energy and undulator period leads to a more compact free-electron laser, while the high beam brightness reduces the gain length and increases the coherent radiation intensity.

Pellegrini, Claudio [UCLA Department of Physics and Astronomy, Los Angeles, CA 90095-1547 (United States)

2009-09-10

42

X-ray Analysis of Sand  

NSDL National Science Digital Library

This is an x-ray diffraction analysis of six sand samples and comparison with hand specimens. Students look at each of the six samples under the binocular microscope and note such useful properties as number of minerals, cleavage/fracture, color, shape, grain size, roundness, and degree of sorting. Then they grind up small amounts of each sample and mount them on glass slides for X-ray. Students write all sample descriptions and X-ray analysis results in their lab notebook. Then they identify the minerals in each sample, determine where they are from, and write a report summarizing all results.

Perkins, Dexter

43

Multifractal analysis of the microdistribution of elements in sedimentary structures using images from scanning electron microscopy and energy dispersive X ray spectrometry  

Microsoft Academic Search

A novel method for the quantitative characterization of density distributions of elements in sedimentary geosystems is presented. This general technique is based on the multifractal analysis of image-processed elemental maps obtained by scanning electron microscopy combined with energy dispersive X ray spectrometry. Application to microdistributions of Si, Fe, and Al in recent bioactive siliciclastic marine sediments are reported. Inhomogeneous scaling

A. Block; W. von Bloh; T. Klenke; H. J. Schellnhuber

1991-01-01

44

Forensic analysis of soil and sediment traces by scanning electron microscopy and energy-dispersive X-ray analysis: An experimental investigation  

Microsoft Academic Search

This paper reports the results of a series of experiments carried out to determine the precision of soil trace comparisons based on elemental peak height ratios determined by energy-dispersive X-ray analysis (EDXRA) in a variable pressure scanning electron microscope (VP-SEM). Experiments were conducted on ‘bulk’ soil aggregates, ground powders prepared from the <150?m soil fractions and on smears of both

Kenneth Pye; Debra Croft

2007-01-01

45

Scanning electron microscopy, X-ray diffraction and thermal analysis study of the TiH{sub 2} foaming agent  

SciTech Connect

The decomposition of commercially available TiH{sub 2} was investigated while performing different thermal treatments. TiH{sub 2} powder, which is widely used as a foaming agent, was heat treated at 450 Degree-Sign C for various times, from 15 min to 120 min. Scanning electron microscopy (SEM) images of the surfaces at different magnifications were obtained and interpreted. A Bragg-Brentano X-ray diffractometer was used to measure the X-ray diffraction (XRD) spectra on all five samples. A close examination of the diffraction spectra showed that for an as-received sample and samples undergoing the longest thermal treatment (1 and 2 h) these spectra can be explained as deriving from cubic TiH{sub 1.924}, while for the other two samples they can be explained as deriving from tetragonal TiH{sub 1.924}. A constant-unit-cell-volume phase transition between the cubic and tetragonal phases in TiH{sub 2-y}-type compounds had been described in the literature. The unit-cell parameters obtained from measured spectra confirm that within the measurement uncertainty the unit-cell volume is indeed constant in all five samples. Thermo-gravimetry (TG) and differential thermal analysis (DTA) measurements were performed on all the samples, showing that the intensity of the dehydrogenation depends on the previous treatment of the TiH{sub 2}. After the thermal analysis XRD of the samples was performed again and the material was found to exhibit a Ti-like unit cell, but slightly enlarged due to the unreleased hydrogen. - Highlights: Black-Right-Pointing-Pointer TiH{sub 2} samples were cubic or tetragonal TiH{sub 1.924} Black-Right-Pointing-Pointer Onset of the hydrogen release temperature increases with the pre-treatment time. Black-Right-Pointing-Pointer Thermal dehydrogenation for the as-prepared TiH{sub 2} is a three-step process. Black-Right-Pointing-Pointer After thermal analysis 2 residual hydrogen TiH{sub x} phases, close to {alpha}Ti, appeared.

Mandrino, Djordje, E-mail: djordje.mandrino@imt.si [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia)] [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia); Paulin, Irena [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia)] [Institute of Metals and Technology, Lepi pot 11, 1000 Ljubljana (Slovenia); Skapin, Sreco D. [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)] [Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)

2012-10-15

46

Improvement of analysis precision upon the atomic number and electron density measurement by the dual x-ray CT  

NASA Astrophysics Data System (ADS)

To identify the factor impairing the material identification parameters, which is provided by the dual-energy X-ray computed tomography method using a conventional X-ray tube and a CdTe detector, linear attenuation coefficient was measured by the radioactivity of radio isotopes and compared with theoretical figure. In our study, the atomic number and the electron density is calculated from the linear attenuation coefficient obtained in CT measurement by 64-channel CdTe line detector. To estimate accuracy of CdTe line sensor, it is needed to obtain the linear attenuation coefficient accurately. Using a single detector, the linear attenuation coefficient is verified for accuracy. The energy resolution of CdTe detectors and the method of reconstruction are discussed.

Imura, Yukino; Morii, Hisashi; Koike, Akifumi; Okunoyama, Takaharu; Neo, Yoichiro; Mimura, Hidenori; Aoki, Toru

2010-08-01

47

Visualization and detectability of elements rarely contained in soft tissue by X-ray scanning analytical microscopy and electron-probe micro analysis.  

PubMed

The detectability of elements rarely contained in soft tissue was compared using X-ray scanning analytical microscope (XSAM) and electron-probe micro analysis (EPMA). Mapping images of Ca, S and P in normal soft tissue of the rat and dissolved Ni in Ni implanted soft tissue could be obtained by XSAM and EPMA. EPMA was more sensitive in detection of P, while XSAM was superior for Ca, S and Ni mapping. The high detectability for heavier elements by XSAM was explained by the large volume of characteristic X-ray generation in XSAM and low attenuation of the characteristic X-rays from heavier elements. XSAM could provide clearer mapping images for heavier elements whose concentration was low without radiation damage to specimens. PMID:11396882

Uo, M; Watari, F; Yokoyama, A; Matsuno, H; Kawasaki, T

2001-07-01

48

Application of scanning electron microscopy to x-ray analysis of frozen- hydrated sections. I. Specimen handling techniques  

Microsoft Academic Search

X-ray microanalysis of frozen-hydrated tissue sections permits direct quantitative analysis of diffusibleelements in defined cellularcompartments . Because the sections are hydrated, elemental concentrations can be defined as wet-weight mass fractions.Use of these techniques should also permit determination of water fraction in cellular compartments . Reliablepreparative techniques provide flat,smooth, 0.5p,m-thicksections with littleelemental and morphological disruption.The specimen support and transfersystem described permits

ALBERT J. SAUBERMANN; PATRICK ECHLIN; PATRICIA D. PETERS; REINIER BEEUWKES

1981-01-01

49

Use of electron microprobe x-ray analysis for determination of low calcium concentrations across leaves deficient in calcium  

NASA Technical Reports Server (NTRS)

An electron microprobe with wavelength-dispersive x-ray spectrometry (WDS) was found to be useful for the determination of Ca concentrations in leaf tissue deficient in Ca. WDS effectively detected Ca concentrations as low as 0.2 mg/g dry wt in the presence of high levels of K and Mg (120 and 50 mg/g dry wt, respectively). Leaf specimens were prepared for analysis by quick-freezing in liquid nitrogen and freeze-drying at -20 degrees C to maintain elemental integrity within the tissue. Because dry material was analyzed, sample preparation was simple and samples could be stored for long periods before analysis. A large beam diameter of 50 gm was used to minimize tissue damage under the beam and analyze mineral concentrations within several cells at one time. Beam penetration was between 50 and 55 microns, approximately one-third of the thickness of the leaf. For analysis of concentrations in interveinal areas, analyses directed into the abaxial epidermis were found most useful. However, because of limited beam penetration, analyses of veinal areas would require use of cross sections [correction of crosssections]. Solid mineral standards were used for instrument standardization. To prevent measurement errors resulting from differences between the matrix of the mineral standards and the analyzed tissue, concentrations in leaves were corrected using gelatin standards prepared and analyzed under the same conditions. WDS was found to be useful for documenting that very low Ca levels occur in specific areas of lettuce leaves exhibiting the Ca deficiency injury termed tipburn.

Barta, D. J.; Tibbitts, T. W.

1991-01-01

50

Analysis of a Novel Diffractive Scanning Wire Beam Position Monitor (BPM) for Discriminative Profiling of Electron Vs. X Ray Beams  

SciTech Connect

Recent numerical studies of Free Electron Lasers (FELs) operating in the Self Amplified Spontaneous Emission (SASE) regime indicate a large sensitivity of the gain to the degree of transverse overlap (and associated phase coherence) between the electron and photon beams traveling down the insertion device. Simulations of actual systems imply that accurate detection and correction for this relative loss of overlap, rather than correction for the absolute departure of the electron beam from a fixed axis, is the preferred function of an FEL amplifier's Beam Position Monitor (BPM) and corrector systems. In this note we propose a novel diffractive BPM with the capability of simultaneously detecting and resolving the absolute (and relative) transverse positions and profiles of electron and x-ray beams co-propagating through an undulator. We derive the equations governing the performance of the BPM and examine its predicted performance for the SLAC Linac Coherent Light Source (LCLS), viz., for profiling multi-GeV electron bunches co-propagating with one-to-several-hundred keV x-ray beams. Selected research and development (r&d) tasks for fabricating and testing the proposed BPM are discussed.

Tatchyn, Roman; /SLAC

2011-09-01

51

Femtosecond x-ray absorption spectroscopy with hard x-ray free electron laser  

SciTech Connect

We have developed a method of dispersive x-ray absorption spectroscopy with a hard x-ray free electron laser (XFEL), generated by a self-amplified spontaneous emission (SASE) mechanism. A transmission grating was utilized for splitting SASE-XFEL light, which has a relatively large bandwidth (?E/E ? 5 × 10{sup ?3}), into several branches. Two primary split beams were introduced into a dispersive spectrometer for measuring signal and reference spectra simultaneously. After normalization, we obtained a Zn K-edge absorption spectrum with a photon-energy range of 210 eV, which is in excellent agreement with that measured by a conventional wavelength-scanning method. From the analysis of the difference spectra, the noise ratio was evaluated to be ?3 × 10{sup ?3}, which is sufficiently small to trace minute changes in transient spectra induced by an ultrafast optical laser. This scheme enables us to perform single-shot, high-accuracy x-ray absorption spectroscopy with femtosecond time resolution.

Katayama, Tetsuo; Togashi, Tadashi; Tono, Kensuke; Kameshima, Takashi [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)] [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Inubushi, Yuichi; Sato, Takahiro; Hatsui, Takaki; Yabashi, Makina [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)] [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Obara, Yuki; Misawa, Kazuhiko [Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan)] [Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Bhattacharya, Atanu; Kurahashi, Naoya [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan)] [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Ogi, Yoshihiro [Molecular Reaction Dynamics Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako 351-0198 (Japan)] [Molecular Reaction Dynamics Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako 351-0198 (Japan); Suzuki, Toshinori [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan) [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Molecular Reaction Dynamics Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako 351-0198 (Japan)

2013-09-23

52

Scanning electron microscopy and energy-dispersive X-ray analysis of self-etching adhesive systems to ground and unground enamel  

Microsoft Academic Search

The morphological analysis of the ground and unground enamel was treated with three different self-etching adhesive systems.\\u000a Ultrastructural features were observed by using the field emission scanning electron microscope (FESEM) in combination with\\u000a Energy Dispersive X-Ray Spectroscopy (EDS) analysis. Thirty extracted human molars were used for this study. Teeth were divided\\u000a into two groups. In the first group unground enamel

Dinesh D. S. Weerasinghe; Toru Nikaido; Shizuko Ichinose; Kanchana G. P. Waidyasekara; Junji Tagami

2007-01-01

53

Resin-slide for X-ray analysis of inorganic deposits on paraffin sections in the scanning electron microscope.  

PubMed

A preparation method for x-ray analysis of inorganic deposits on paraffin sections is described. It involves the use of resin-slides for mounting paraffin sections which are then dewaxed, carboncoated and examined in the SEM. The resin support, being much cheaper than the carbon planchet and having a perfectly flat surface, facilitates the adhesion of paraffin sections to it, and slides can be stored desiccated for retrospective study. The method also permits direct examination of sections under a light microscope to locate areas of interest. It is simple and useful for the analysis of inorganic inclusions in biological samples. PMID:6096794

Or, S B; Ngai, H K; Yau, W L

1984-07-01

54

Analysis of 20 KEV Electron Induced X-Ray Production in Skull, Femur/tibia Bones of Rats  

NASA Astrophysics Data System (ADS)

Hind-limb suspension (HLS) of rats is a NASA validated model of simulated weightlessness. This study examines the effects of microgravity on the skeletal system of rats to assess whether or not exposure of rats to HLS for one week will induce alteration of structural features in selected bones. Four groups of rats were used: two unsuspended controls and two suspended groups. Body weight, food, and water intake were monitored daily before and after suspension. X-rays were measured by a liquid nitrogen cooled Si(li) detector on a Scanning Electron Microscope (SEM) that provided the 20 keV electron beam. X-ray data were collected from square cross sections between 100 ?m2 and 104 ?m2. The bones were measured for elemental levels of calcium, phosphorus, oxygen and carbon from both control and HLS rats. The average body weight of all HLS groups decreased compared to their respective unsuspended controls. Food and water intake was also lower in both suspended groups. A correlation among HLS and control samples in terms of the distribution of the primary elements was found in the bone tissue when analyzed as a function of position along the hind-leg and within the cross sections.

Mehta, Rahul; Watson, Alec; Ali, Nawab; Soulsby, Michael; Chowdhury, Parimal

2010-04-01

55

Fundamental characteristics of hybrid X-ray focusing optics for micro X-ray fluorescence analysis  

NASA Astrophysics Data System (ADS)

We developed a hybrid X-ray focusing optics, which consisted of a polycapillary X-ray lens (PCXL) and a tungsten conical pinhole (WCP) for micro X-ray fluorescence (?-XRF) analysis. A single PCXL produced an X-ray micro beam with a spot size of 12 ?m. We developed a WCP by using a laser-ablation technique with an input diameter of 39 ?m, an output diameter of 2.5 ?m, and a thickness of 0.5 mm in a conical shape. This hybrid X-ray optics gave a small spot size of 2.8 ?m with a small divergent angle of 12 mrad.

Komatani, Shintaro; Nakamachi, Kazuo; Nakano, Kazuhiko; Ohzawa, Sumito; Uchihara, Hiroshi; Bando, Atsushi; Tsuji, Kouichi

2013-08-01

56

Complementary analysis of historical glass by scanning electron microscopy with energy dispersive X-ray spectroscopy and laser ablation inductively coupled plasma mass spectrometry  

Microsoft Academic Search

.  Laser ablation inductively coupled plasma mass spectrometry (LA ICP MS) was used as a supporting method for elemental analysis\\u000a of historical glass investigated by means of scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM\\/EDS).\\u000a Investigated objects represent mainly late- and post-medieval glass objects (mostly Façon-de-Venise vessels and nuppenbechers), window glass and chandeliers from excavation in Elbl?g, Pozna? and Wroc?aw

Barbara Wagner; Anna Nowak; Ewa Bulska; Jerzy Kunicki-Goldfinger; Olivier Schalm; Koen Janssens

2008-01-01

57

The Swift X-ray Telescope Cluster Survey. II. X-ray spectral analysis  

NASA Astrophysics Data System (ADS)

Aims: We present a spectral analysis of a new, flux-limited sample of 72 X-ray selected clusters of galaxies identified with the X-ray Telescope (XRT) on board the Swift satellite down to a flux limit of ~10-14 erg s-1 cm-2 (SWXCS). We carry out a detailed X-ray spectral analysis with the twofold aim of measuring redshifts and characterizing the properties of the intracluster medium (ICM) for the majority of the SWXCS sources. Methods: Optical counterparts and spectroscopic or photometric redshifts for some of the sources are obtained with a cross-correlation with the NASA/IPAC Extragalactic Database. Additional photometric redshifts are computed with a dedicated follow-up program with the Telescopio Nazionale Galileo and a cross-correlation with the SDSS. In addition, we also blindly search for the Hydrogen-like and He-like iron K? emission line complex in the X-ray spectrum. We detect the iron emission lines in 35% of the sample, and hence obtain a robust measure of the X-ray redshift zX with typical rms error 1-5%. We use zX whenever the optical redshift is not available. Finally, for all the sources with measured redshift, background-subtracted spectra are fitted with a single-temperature mekal model to measure global temperature, X-ray luminosity and iron abundance of the ICM. We perform extensive spectral simulations to accounts for fitting bias, and to assess the robustness of our results. We derive a criterion to select reliable best-fit models and an empirical formula to account for fitting bias. The bias-corrected values are then used to investigate the scaling properties of the X-ray observables. Results: Overall, we are able to characterize the ICM of 46 sources with redshifts (64% of the sample). The sample is mostly constituted by clusters with temperatures between 3 and 10 keV, plus 14 low-mass clusters and groups with temperatures below 3 keV. The redshift distribution peaks around z ~ 0.25 and extends up to z ~ 1, with 60% of the sample at 0.1 < z < 0.4. We derive the luminosity-temperature relation for these 46 sources, finding good agreement with previous studies. Conclusions: Thanks to the good X-ray spectral quality and the low background of Swift/XRT, we are able to measure ICM temperatures and X-ray luminosities for the 46 sources with redshifts. Once redshifts are available for the remaining 26 sources, this sample will constitute a well-characterized, flux-limited catalog of clusters distributed over a broad redshift range (0.1 ? z ? 1.0) providing a statistically complete view of the cluster population with a selection function that allows a proper treatment of any measurement bias. The quality of the SWXCS sample is comparable to other samples available in the literature and obtained with much larger X-ray telescopes. Our results have interesting implications for the design of future X-ray survey telescopes, characterized by good-quality PSF over the entire field of view and low background. Tables 1 and 2 and Appendix A are available in electronic form at http://www.aanda.orgCatalog and data products of SWXCS, constantly updated, are made available to the public through the websites http://www.arcetri.astro.it/SWXCS/ and http://swxcs.ustc.edu.cn/

Tozzi, P.; Moretti, A.; Tundo, E.; Liu, T.; Rosati, P.; Borgani, S.; Tagliaferri, G.; Campana, S.; Fugazza, D.; D'Avanzo, P.

2014-07-01

58

Fundamental physics with an X-ray free electron laser  

Microsoft Academic Search

Of late, laboratories around the world are considering building X-ray free electron lasers based on high energy electron accelerators\\u000a (with energies exceeding 10 GeV) to produce bright coherent X rays with wavelengths on the order of 1 . Because of the extremely\\u000a small wavelength and high brilliance of these coherent X rays, there is an unprecedented opportunity to explore new

T. Tajima

2003-01-01

59

Quantitative x-ray spectrometry using the environmental scanning electron microscope  

Microsoft Academic Search

It is desirable to know the elemental composition of features viewed in the environmental scanning electron microscope (ESEM) using energy dispersive x-ray spectrometry (EDS). This analysis is complicated by the spread of the electron beam by chamber gas molecules and the necessity for charge neutralization. The research reported herein assesses the feasibility of doing x-ray analysis in the ESEM. The

Robert A. Carlton

2001-01-01

60

Multivariate statistical analysis of particle x-ray spectra  

Microsoft Academic Search

Multivariate statistical analysis (MSA) is a powerful tool for the analysis of series of spectra. This paper explores an application of MSA to a series of energy dispersive X-ray (EDX) spectra acquired in the scanning electron microscope (SEM) from a series of particles. The raw data were series of spectra previously acquired to test analytical procedures for trace element detection.

I. M. Anderson; J. A. Small

1998-01-01

61

X-Ray Zone Plates Fabricated Using Electron-Beam and X-Ray Lithography.  

National Technical Information Service (NTIS)

Fresnel zone plate patterns, free of spherical abberation, with diameters of up to 0.63 mm and linewidths as small as 1000 A were fabricated on polyimide-membrane x-ray masks using scanning electron beam lithography Distortion of the electron beam scan ra...

D. C. Shaver D. C. Flanders N. M. Ceglio H. I. Smith

1979-01-01

62

Density gradient free electron collisionally excited x-ray laser  

DOEpatents

An operational x-ray laser is provided that amplifies 3p-3s transition x-ray radiation along an approximately linear path. The x-ray laser is driven by a high power optical laser. The driving line focused optical laser beam illuminates a free-standing thin foil that may be associated with a substrate for improved structural integrity. This illumination produces a generally cylindrically shaped plasma having an essentially uniform electron density and temperature, that exists over a long period of time, and provides the x-ray laser gain medium. The x-ray laser may be driven by more than one optical laser beam. The x-ray laser has been successfully demonstrated to function in a series of experimental tests.

Campbell, E.M.; Rosen, M.D.

1984-11-29

63

Fundamental studies of X-ray and secondary electron spectroscopy  

NASA Astrophysics Data System (ADS)

Microanalysis of submicron particles in the Scanning Electron Microscope (SEM) is only possible by using low incident electron beam energies due to smaller interaction volume and suppressed beam induced charging. Such low beam energies must use L- and M-lines rather than the familiar K-lines. The information about the fundamental parameters of X-ray emission and transport at low energies is limited, so the use of L- and M-lines is problematic. The rate of generation of X-rays from an element irradiated at some energy E depends on the product of the ionization cross-section sigma(E) and the fluorescent yield o. Unfortunately neither of these quantities is well established independently, especially outside of the K-series of lines. Therefore the absolute X-ray generation efficiencies (photons/electron) were directly measured and parameterized for a wide range of K, L , and M lines from different elements. It is anticipated that a complete set of such data would be of great value in applications such as spectrum simulation and standardless analysis. Secondary electron spectra have been collected from both pure elements and from compounds examined under conditions approximating those found in a scanning electron microscope. Despite the presence of substantial surface contamination these spectra are found to be reproducible and characteristic of the underlying material. Typically the peak in such spectra is found to be at an energy of about 5 eV, and 50% of the total secondary electron emission falls within the range 0--12 eV. These data may be of value for the design of detectors for scanning microscopy and might have applications for microanalysis.

Mulapudi, Satya Prasad

64

Growth and texture of spark plasma sintered Al2O3 ceramics: A combined analysis of X-rays and electron back scatter diffraction  

NASA Astrophysics Data System (ADS)

Textured alumina ceramics were obtained by Spark Plasma Sintering of undoped commercial ?-Al2O3 powders. Various parameters (density, grain growth, grain size distribution) of the alumina ceramics, sintered at two typical temperatures 1400 °C and 1700 °C, are investigated. Quantitative textural and structural analysis, carried out using a combination of Electron Back Scattering Diffraction and X-ray diffraction, are represented in the form of mapping and pole figures. The mechanical properties of these textured alumina ceramics include high elastic modulus and hardness values with high anisotropic nature, opening the door for a large range of applications.

Pravarthana, D.; Chateigner, D.; Lutterotti, L.; Lacotte, M.; Marinel, S.; Dubos, P. A.; Hervas, I.; Hug, E.; Salvador, P. A.; Prellier, W.

2013-04-01

65

Micro and imaging x-ray analysis by using polycapillary x-ray optics  

NASA Astrophysics Data System (ADS)

We have studied the micro x-ray fluorescence (XRF) and 2D- or 3D-XRF analysis in the laboratory by using polycapillary optics. A confocal 3D micro-XRF instrument was applied for solid/liquid interface analysis. 2D elemental maps of x-ray fluorescence for the solid surface of an Fe plate after Cu was deposited by chemical plating were obtained. The 2D images could be taken in the solution. This result suggests that this 3D micro-XRF method is useful for in-situ monitoring of chemical reactions on solid-liquid interfaces. Furthermore, we have reported a new application of polycapillary x-ray optics. Two independent straight polycapillary optics were arranged between the sample and an x-ray energy dispersive detector. X-ray fluorescence emitted from the sample was collimated by the first capillary, and then it was introduced into the second capillary. By adjusting the angle between two capillary optics, only the x-rays totally reflected on the inner wall of the second capillary could be detected by the x-ray detector. This result suggests that we can use these polycapillary optics for x-ray energy filtering optics.

Tsuji, Kouichi; Nakano, Kazuhiko; Yamaguchi, Makoto; Yonehara, Tasuku

2008-08-01

66

Structural and electron density changes in dense guest-host systems: Analysis of X-ray diffraction data by the Rietveld and Maximum Entropy Methods  

Microsoft Academic Search

When studying the high-pressure structural behavior of crystalline materials, it is highly desirable to determine structural changes accurately, preferably at electron density levels. The Maximum Entropy Method (MEM) has already proven to be a very powerful tool for extracting the most probable charge density distributions directly from X-ray diffraction data. This thesis presents high pressure X-ray diffraction studies on two

Roxana Ioana Flacau

2007-01-01

67

Micro and imaging x-ray analysis by using polycapillary x-ray optics  

Microsoft Academic Search

We have studied the micro x-ray fluorescence (XRF) and 2D- or 3D-XRF analysis in the laboratory by using polycapillary optics. A confocal 3D micro-XRF instrument was applied for solid\\/liquid interface analysis. 2D elemental maps of x-ray fluorescence for the solid surface of an Fe plate after Cu was deposited by chemical plating were obtained. The 2D images could be taken

Kouichi Tsuji; Kazuhiko Nakano; Makoto Yamaguchi; Tasuku Yonehara

2008-01-01

68

Synchrotron x-ray fluorescence and extended x-ray absorption fine structure analysis  

SciTech Connect

The advent of dedicated synchrotron radiation sources has led to a significant increase in activity in many areas of science dealing with the interaction of x-rays with matter. Synchrotron radiation provides intense, linearly polarized, naturally collimated, continuously tunable photon beams, which are used to determine not only the elemental composition of a complex, polyatomic, dilute material but also the chemical form of the elements with improved accuracy. Examples of the application of synchrotron radiation include experiments in synchrotron x-ray fluorescence (SXRF) analysis and extended x-ray absorption fine structure (EXAFS) analysis. New synchrotron radiation x-ray microprobes for elemental analysis in the parts per billion range are under construction at several laboratories. 76 references, 24 figures.

Chen, J.R.; Gordon, B.M.; Hanson, A.L.; Jones, K.W.; Kraner, H.W.; Chao, E.C.T.; Minkin, J.A.

1984-01-01

69

Au25(SEt)18, a Nearly Naked Thiolate-Protected Au25 Cluster: Structural Analysis by Single Crystal X-ray Crystallography and Electron Nuclear Double Resonance.  

PubMed

X-ray crystallography has been fundamental in discovering fine structural features of ultrasmall gold clusters capped by thiolated ligands. For still unknown structures, however, new tools capable of providing relevant structural information are sought. We prepared a 25-gold atom nanocluster protected by the smallest ligand ever used, ethanethiol. This cluster displays the electrochemistry, mass spectrometry, and UV-vis absorption spectroscopy features of similar Au25 clusters protected by 18 thiolated ligands. The anionic and the neutral form of Au25(SEt)18 were fully characterized by (1)H and (13)C NMR spectroscopy, which confirmed the monolayer's properties and the paramagnetism of neutral Au25(SEt)18(0). X-ray crystallography analysis of the latter provided the first known structure of a gold cluster protected by a simple, linear alkanethiolate. Here, we also report the direct observation by electron nuclear double resonance (ENDOR) of hyperfine interactions between a surface-delocalized unpaired electron and the gold atoms of a nanocluster. The advantages of knowing the exact molecular structure and having used such a small ligand allowed us to compare the experimental values of hyperfine couplings with DFT calculations unaffected by structure's approximations or omissions. PMID:24628268

Dainese, Tiziano; Antonello, Sabrina; Gascón, José A; Pan, Fangfang; Perera, Neranjan V; Ruzzi, Marco; Venzo, Alfonso; Zoleo, Alfonso; Rissanen, Kari; Maran, Flavio

2014-04-22

70

Recent Advances in X-Ray Free Electron Lasers  

NASA Astrophysics Data System (ADS)

X-ray free electron lasers(FELs) are undergoing an exciting development. They will soon become a reality with the commissioning of the LCLS in early next year, soon followed by Spring 8 X-FEL and the European XFEL at Hamburg. Intense, coherent pulses of x-rays from these machines will permit exploration of the atomic world with spatial and temporal precisions hitherto not feasible. After these first generation x-ray FELs based on self-amplified spontaneous emission (SASE) in a single pass high-gain system, the next generation devices for higher performance and/or smaller and lower cost are under various stages of development. In the soft x-ray region, seeded FELs with high harmonic generated (HHG) laser input will produce coherent output in a shorter system. Drastic improvement in hard x-ray region is possible with new types of electron injectors producing electron beams with an order of magnitude smaller emittance. Hard x-ray FELs can be built with an order of magnitude smaller electron energy and thus with a significant savings in the cost. The Spring-8 FEL is a first step in this direction. Novel types of FELs are possible; ultra-short SASE providing sub-fs time-resolution and x-ray FEL oscillator (XFELO) providing ultra-narrow spectral resolution. The XFELO employs optical cavity formed by Bragg reflectors, delivering temporally and spatially coherent hard x-rays, with meV spectral resolution. Its peak spectral brightness is similar to but the average spectral brightness is about five orders of magnitudes higher than LCLS.

Kim, Kwang-Je

2009-03-01

71

Asbestos Characterization using Scanning Electron Microscopy/Light Element X-ray Spectrometry.  

National Technical Information Service (NTIS)

The Defence Research Establishment Atlantic(DREA) has traditionally used scanning electron microscopy (SEM) coupled with energy dispersive x-ray (EDX) spectrometry to identify asbestos fibers in solid insulating materials. This analysis typically utilizes...

G. C. Fisher R. M. Morchat

1993-01-01

72

Electron beam and x-ray resists  

US Patent & Trademark Office Database

Polymers are disclosed comprising a poly(vinyl alcohol) backbone with the following groups or combination of groups bound to the backbone: (A) (substituted alkyl)benzoyl groups; or (B) (substituted alkyl)benzoyl groups, and (vinyl)benzoyl groups; or (C) (substituted alkyl)benzoyl groups, and (halo)benzoyl groups or (2-carboxy-3,4,5,6-tetrachloro) benzoyl groups; (D) (substituted alkyl)benzoyl groups, (vinyl) benzoyl groups, and (halo)benzoyl groups or (2-carboxy-3,4,5,6-tetrachloro)benzoyl groups; (E) (vinyl)benzoyl groups, and (halo)benzoyl groups or (2-carboxy-3,4,5,6-tetrachloro) benzoyl groups; or (F) (halo)benzoyl groups. Each of these polymers can optionally contain, bound to the poly(vinyl alcohol) backbone, (trialkylsily) benzoyl groups. The benzoyl groups are randomly bound to the poly(vinyl alcohol) by ester linkages. Residual pendant hydroxy groups remain after the attachment of the benzoyl groups. Also disclosed are the use of these polymers as radiation sensitive resists, such as, for example, x-ray and/or E-beam resists.

1989-09-19

73

The analysis of primer mixtures and gunshot residues using scanning electron microscopy\\/energy dispersive X-ray analysis  

Microsoft Academic Search

Although the analysis of GSR using SEM\\/EDX has been thoroughly studied, no literature on the SEM\\/EDX analysis of primer mixtures of center-fired cartridges has been reported. Thus, not only GSR but also primer mixtures generated from both reference cartridges and confiscated illegal cartridges were analyzed in this work. The aim of this work is to obtain elemental composition data of

Hsien-Hui Meng; Hsei-Chang Lee; Yu-Liang Chen

2003-01-01

74

Crystallization and preliminary X-ray diffraction analysis of a complex between the electron-transfer partners hexameric Cu-containing nitrite reductase and pseudoazurin  

PubMed Central

The complex between Cu-containing nitrite reductase (HdNIR) and its electron-donor protein pseudoazurin (HdPAz) from Hyphomicrobium denitrificans has been crystallized. The crystals were obtained from a mixture of the two proteins using the hanging-drop vapour-diffusion method in the presence of polyethylene glycol (PEG) and 2-methyl-2,4-pentanediol (MPD) as precipitants. SDS–PAGE analysis demonstrated that the crystals contained both proteins. The X-ray diffraction experiment was carried out at SPring-8 and diffraction data were collected to 3.3?Å resolution. The crystals were tetragonal (space group P41212), with unit-cell parameters a = b = 130.39, c = 505.55?Å. Preliminary analysis indicated that there was one HdNIR and at least two HdPAz molecules in the asymmetric unit of the crystal.

Hira, Daisuke; Nojiri, Masaki; Suzuki, Shinnichiro

2009-01-01

75

Flash X-Ray (FXR) Accelerator Optimization Electronic Time-Resolved Measurement of X-Ray Source Size  

SciTech Connect

Lawrence Livermore National Laboratory (LLNL) is currently investigating various approaches to minimize the x-ray source size on the Flash X-Ray (FXR) linear induction accelerator in order to improve x-ray flux and increase resolution for hydrodynamic radiography experiments. In order to effectively gauge improvements to final x-ray source size, a fast, robust, and accurate system for measuring the spot size is required. Timely feedback on x-ray source size allows new and improved accelerator tunes to be deployed and optimized within the limited run-time constraints of a production facility with a busy experimental schedule; in addition, time-resolved measurement capability allows the investigation of not only the time-averaged source size, but also the evolution of the source size, centroid position, and x-ray dose throughout the 70 ns beam pulse. Combined with time-resolved measurements of electron beam parameters such as emittance, energy, and current, key limiting factors can be identified, modeled, and optimized for the best possible spot size. Roll-bar techniques are a widely used method for x-ray source size measurement, and have been the method of choice at FXR for many years. A thick bar of tungsten or other dense metal with a sharp edge is inserted into the path of the x-ray beam so as to heavily attenuate the lower half of the beam, resulting in a half-light, half-dark image as seen downstream of the roll-bar; by measuring the width of the transition from light to dark across the edge of the roll-bar, the source size can be deduced. For many years, film has been the imaging medium of choice for roll-bar measurements thanks to its high resolution, linear response, and excellent contrast ratio. Film measurements, however, are fairly cumbersome and require considerable setup and analysis time; moreover, with the continuing trend towards all-electronic measurement systems, film is becoming increasingly difficult and expensive to procure. Here, we shall discuss an x-ray source size measurement system which utilizes a traditional roll-bar setup combined with a high resolution gated CCD camera, fast-response organic plastic scintillator, and image processing and analysis software, which is executable on a standard PC running which is executable on a standard PC running LabVIEW and Matlab. Analysis time is reduced from several hours to several minutes, while our experimental results demonstrate good agreement with both traditional film-based roll-bar measurements as well as the entirely unrelated technique of x-ray pinhole camera measurements; in addition, our time-resolved measurements show a significant variation in source size throughout the 70 ns beam pulse, a phenomenon which requires further investigation and indicates the possibility of greatly improving final spot size.

Jacob, J; Ong, M; Wargo, P

2005-07-21

76

Andrographolide: an X-ray crystallographic analysis  

Microsoft Academic Search

The structure of andrographolide, isolated fromAndrographis paniculata Nees, has been established by means of a single crystal X-ray analysis. The crystals have the space groupP21, witha=6.550(1),b=8.005(2),c=17.991(7) Å,ß=97.36(2)°, andZ=2. The structure was refined toR=7.3%. The molecular stereochemistry, bond distances, bond angles, and hydrogen bonding scheme have all been determined. The systematic name is 3-[2-[decahydro-6-hydroxy-5-(hydroxymethyl)-5,8a-dimethyl-2-methylene-1-naphthalenyl]ethylidine]dihydro-4-hydroxy-2(3H)-furanone.

Amos B. Smith; Bruce H. Toder; Patrick J. Carroll; Jerry Donohue

1982-01-01

77

Exotic X-ray Sources from Intermediate Energy Electron Beams  

NASA Astrophysics Data System (ADS)

High intensity x-ray beams are used in a wide variety of applications in solid-state physics, medicine, biology and material sciences. Synchrotron radiation (SR) is currently the primary, high-quality x-ray source that satisfies both brilliance and tunability. The high cost, large size and low x-ray energies of SR facilities, however, are serious limitations. Alternatively, ``novel'' x-ray sources are now possible due to new small linear accelerator (LINAC) technology, such as improved beam emittance, low background, sub-Picosecond beam pulses, high beam stability and higher repetition rate. These sources all stem from processes that produce Radiation from relativistic Electron beams in (crystalline) Periodic Structures (REPS), or the periodic ``structure'' of laser light. REPS x-ray sources are serious candidates for bright, compact, portable, monochromatic, and tunable x-ray sources with varying degrees of polarization and coherence. Despite the discovery and early research into these sources over the past 25 years, these sources are still in their infancy. Experimental and theoretical research are still urgently needed to answer fundamental questions about the practical and ultimate limits of their brightness, mono-chromaticity etc. We present experimental results and theoretical comparisons for three exotic REPS sources. These are Laser-Compton Scattering (LCS), Channeling Radiation (CR) and Parametric X-Radiation (PXR).

Chouffani, K.; Wells, D.; Harmon, F.; Jones, J. L.; Lancaster, G.

2003-08-01

78

Exotic X-ray Sources from Intermediate Energy Electron Beams  

SciTech Connect

High intensity x-ray beams are used in a wide variety of applications in solid-state physics, medicine, biology and material sciences. Synchrotron radiation (SR) is currently the primary, high-quality x-ray source that satisfies both brilliance and tunability. The high cost, large size and low x-ray energies of SR facilities, however, are serious limitations. Alternatively, 'novel' x-ray sources are now possible due to new small linear accelerator (LINAC) technology, such as improved beam emittance, low background, sub-Picosecond beam pulses, high beam stability and higher repetition rate. These sources all stem from processes that produce Radiation from relativistic Electron beams in (crystalline) Periodic Structures (REPS), or the periodic 'structure' of laser light. REPS x-ray sources are serious candidates for bright, compact, portable, monochromatic, and tunable x-ray sources with varying degrees of polarization and coherence. Despite the discovery and early research into these sources over the past 25 years, these sources are still in their infancy. Experimental and theoretical research are still urgently needed to answer fundamental questions about the practical and ultimate limits of their brightness, mono-chromaticity etc. We present experimental results and theoretical comparisons for three exotic REPS sources. These are Laser-Compton Scattering (LCS), Channeling Radiation (CR) and Parametric X-Radiation (PXR)

Chouffani, K.; Wells, D.; Harmon, F. [Idaho Accelerator Center, Idaho State University, Pocatello, ID 83209 (United States); Jones, J.L.; Lancaster, G. [Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID 83415-280 (United States)

2003-08-26

79

Food irradiation technology using electron beams and x-rays  

Microsoft Academic Search

In this presentation we will discuss the technology of food irradiation using electron accelerators. Food irradiation has generally come to describe the use of ionizing radiation (e.g., energetic electrons and x-rays) to decrease the population of, or prevent the growth of, undesirable biological organisms in food. The many beneficial applications include for example, the disinfestation of insects in fruits and

R. B. Miller

2002-01-01

80

X-ray Emission from Electron Betatron Motion in a Laser-Plasma Accelerator  

SciTech Connect

Single-shot x-ray spectra from electron bunches produced by a laser-plasma wakefield accelerator (LPA) were measured using a photon-counting single-shot pixelated Silicon-based detector [3], providing for the first time direct spectra without assumptions required by filter based techniques. In addition, the electron bunch source size was measured by imaging a wire target, demonstrating few micron source size and stability. X-rays are generated when trapped electrons oscillate in the focusing field of the wake trailing the driver laser pulse. In addition to improving understanding of bunch emittance and wake structure, this provides a broadband, synchronized femtosecond source of keV x-rays. Electron bunch spectra and divergence were measured simultaneously and preliminary analysis shows correlation between x-ray andelectron spectra. Bremsstrahlung background was managed using shielding and magnetic diversion.

Plateau, Guillaume; Geddes, Cameron; Thorn, Daniel; Matlis, Nicholas; Mittelberger, Daniel; Stoehlker, T; Battaglia, Marco; Kim, Tae; Nakamura, Kei; Esarey, Eric; Leemans, Wim

2011-07-19

81

The History of X-ray Free-Electron Lasers  

SciTech Connect

The successful lasing at the SLAC National Accelerator Laboratory of the Linear Coherent Light Source (LCLS), the first X-ray free-electron laser (X-ray FEL), in the wavelength range 1.5 to 15 {angstrom}, pulse duration of 60 to few femtoseconds, number of coherent photons per pulse from 10{sup 13} to 10{sup 11}, is a landmark event in the development of coherent electromagnetic radiation sources. Until now electrons traversing an undulator magnet in a synchrotron radiation storage ring provided the best X-ray sources. The LCLS has set a new standard, with a peak X-ray brightness higher by ten orders of magnitudes and pulse duration shorter by three orders of magnitudes. LCLS opens a new window in the exploration of matter at the atomic and molecular scales of length and time. Taking a motion picture of chemical processes in a few femtoseconds or less, unraveling the structure and dynamics of complex molecular systems, like proteins, are some of the exciting experiments made possible by LCLS and the other X-ray FELs now being built in Europe and Asia. In this paper, we describe the history of the many theoretical, experimental and technological discoveries and innovations, starting from the 1960s and 1970s, leading to the development of LCLS.

Pellegrini, C.; /UCLA /SLAC

2012-06-28

82

The history of X-ray free-electron lasers  

NASA Astrophysics Data System (ADS)

The successful lasing at the SLAC National Accelerator Laboratory of the Linear Coherent Light Source (LCLS), the first X-ray free-electron laser (X-ray FEL), in the wavelength range 1.5 to 15 Å, pulse duration of 60 to few femtoseconds, number of coherent photons per pulse from 1013 to 1011, is a landmark event in the development of coherent electromagnetic radiation sources. Until now electrons traversing an undulator magnet in a synchrotron radiation storage ring provided the best X-ray sources. The LCLS has set a new standard, with a peak X-ray brightness higher by ten orders of magnitudes and pulse duration shorter by three orders of magnitudes. LCLS opens a new window in the exploration of matter at the atomic and molecular scales of length and time. Taking a motion picture of chemical processes in a few femtoseconds or less, unraveling the structure and dynamics of complex molecular systems, like proteins, are some of the exciting experiments made possible by LCLS and the other X-ray FELs now being built in Europe and Asia. In this paper, we describe the history of the many theoretical, experimental and technological discoveries and innovations, starting from the 1960s and 1970s, leading to the development of LCLS.

Pellegrini, C.

2012-10-01

83

Quantitative energy-dispersive electron probe X-ray microanalysis for single-particle analysis and its application for characterizing atmospheric aerosol particles  

Microsoft Academic Search

.  An energy-dispersive electron probe X-ray microanalysis (ED-EPMA) technique using an energy-dispersive X-ray detector with\\u000a an ultra-thin window, designated as low-Z particle EPMA, has been developed. The low-Z particle EPMA allows the quantitative determination of concentrations of low-Z elements such as C, N and O, as well as higher-Z elements that can be analysed by conventional ED-EPMA. The quantitative determination of

Shila Maskey; Chul-Un Ro

2011-01-01

84

Remineralization of enamel subsurface lesions with casein phosphopeptide-amorphous calcium phosphate: A quantitative energy dispersive X-ray analysis using scanning electron microscopy: An in vitro study  

PubMed Central

Aim: The objective of this study was to quantitatively evaluate the remineralization potential of casein phosphopeptide-amor-phous calcium phosphate paste on enamel subsurface lesions using scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX). Materials and Methods: Ninety enamel specimens were prepared from extracted human molars. All specimens were evaluated for mineral content (% weight) using SEM-EDX. The specimens were placed in demineralizing solution for four days to produce artificial carious lesions. The mineral content (calcium/phosphorus ratios, Ca/P ratios) was remeasured using SEM-EDX. The specimens were then randomly assigned to five study groups and one control group of 15 specimens per group. Except for the control group, all group specimens were incubated in remineralizing paste (CPP-ACP paste) for 7, 14, 21, 28, and 35 days twice daily for three minutes. The control group received no treatment with remineralizing paste. All the 90 specimens were stored in artificial saliva at 37°C. After remineralization, the mineral content (% weight) of the samples was measured using SEM-EDX. Results: All the study groups showed very highly significant differences between Ca/P ratios of the demineralized and remineralized samples. There was no significant difference seen in the control group. Conclusion: CPP-ACP paste could significantly remineralize the artificial enamel subsurface lesions in vitro: the remineralizing rates increasing with the time for which the samples were kept in the remineralizing paste. Energy dispersive X-ray analysis is an efficient way to quantitatively assess the changes in mineral content during demineralization and in vitro remineralization processes.

Hegde, Mithra N; Moany, Anu

2012-01-01

85

An investigation of X-ray fluorescence analysis with an X-ray focusing system (X-ray lens)  

Microsoft Academic Search

Divergent X-ray radiation has been focused into a small spot (diameter 500 mum) by an X-ray lens made of polycapillaries, increasing the power density by 104 times. The new X-ray lens has been applied to the XRF technique. Limits of detection of 10-9-10-10g have been obtained by means of the new technique with an X-ray tube of 2 W power.

Yan Yiming; Ding Xunliang

1993-01-01

86

X-ray fluorescence analysis based on Kumakhov optics  

Microsoft Academic Search

The use of Kumakhov optics in x-ray fluorescence analysis is considered. Thanks to high efficiency of a polycapillary lens the concentration of x-ray detector in a close proximity to the sample decreases sufficiently the time of exposure. It is shown experimentally that in the case of use of a small x-ray source with power of 2W the minimal detection limit

Svetlana V. Nikitina; Nariman S. Ibraimov; Alexander S. Stcherbakov

1998-01-01

87

Bremsstrahlung X rays from Jovian Auroral Electrons (Final Report).  

National Technical Information Service (NTIS)

In a recent paper by D. D. Barbosa, it is argued that electron bremsstrahlung is the most likely source of the auroral x-ray emissions that have been observed at Jupiter. Barbosa bases his argument on observational and theoretical studies of the productio...

J. H. Waite

1991-01-01

88

Molecular imaging using X-ray free-electron lasers.  

PubMed

The opening of hard X-ray free-electron laser facilities, such as the Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory in the United States, has ushered in a new era in structural determination. With X-ray pulse durations down to 10 fs or shorter, and up to 10(13) transversely coherent photons per pulse in a narrow spectral bandwidth, focused irradiances of 10(18) to 10(21) W cm(-2) or higher can be produced at X-ray energies ranging from 500 eV to 10 keV. New techniques for determining the structure of systems that cannot be crystallized and for studying the time-resolved behavior of irreversible reactions at femtosecond timescales are now available. PMID:23331310

Barty, Anton; Küpper, Jochen; Chapman, Henry N

2013-01-01

89

Molecular Imaging Using X-Ray Free-Electron Lasers  

NASA Astrophysics Data System (ADS)

The opening of hard X-ray free-electron laser facilities, such as the Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory in the United States, has ushered in a new era in structural determination. With X-ray pulse durations down to 10 fs or shorter, and up to 1013 transversely coherent photons per pulse in a narrow spectral bandwidth, focused irradiances of 1018 to 1021 W cm-2 or higher can be produced at X-ray energies ranging from 500 eV to 10 keV. New techniques for determining the structure of systems that cannot be crystallized and for studying the time-resolved behavior of irreversible reactions at femtosecond timescales are now available.

Barty, Anton; Küpper, Jochen; Chapman, Henry N.

2013-04-01

90

Feasibility Study of X-Ray Fluorescence for Analysis of Welding and Brazing Fumes.  

National Technical Information Service (NTIS)

An X-ray fluorescence technique (XRF) was developed for the analysis of welding and brazing fumes. Welding or brazing fumes were collected on six standard filter cassettes and examined by electron microscopy and X-ray diffraction to assess the particle si...

T. P. Carsey

1980-01-01

91

Remote X-Ray Diffraction and X-Ray Fluorescence Analysis on Planetary Surfaces  

NASA Technical Reports Server (NTRS)

The legacy of planetary X-ray Diffraction (XRD) and X-ray Fluorescence (XRF) began in 1960 when W. Parish proposed an XRD instrument for deployment on the moon. The instrument was built and flight qualified, but the Lunar XRD program was cancelled shortly before the first human landing in 1969. XRF chemical data have been collected in situ by surface landers on Mars (Viking 1 & 2, Pathfinder) and Venus (Venera 13 & 14). These highly successful experiments provide critical constraints on our current understanding of surface processes and planetary evolution. However, the mineralogy, which is more critical to planetary surface science than simple chemical analysis, will remain unknown or will at best be imprecisely constrained until X-ray diffraction (XRD) data are collected. Recent progress in X-ray detector technology allows the consideration of simultaneous XRD (mineralogic analysis) and high-precision XRF (elemental analysis) in systems miniaturized to the point where they can be mounted on fixed landers or small robotic rovers. There is a variety of potential targets for XRD/XRF equipped landers within the solar system, the most compelling of which are the poles of the moon, the southern highlands of Mars and Europa.

Blake, David F.; DeVincenzi, D. (Technical Monitor)

1999-01-01

92

Analysis of electronic structure of amorphous InGaZnO/SiO{sub 2} interface by angle-resolved X-ray photoelectron spectroscopy  

SciTech Connect

The electronic structures of amorphous indium gallium zinc oxide (a-IGZO) on a SiO{sub 2} layers before and after annealing were observed by constant final state X-ray photoelectron spectroscopy (CFS-XPS) and X-ray adsorption near-edge structure spectroscopy (XANES). From the results of angle-resolved CFS-XPS, the change in the electronic state was clearly observed in the a-IGZO bulk rather than in the a-IGZO/SiO{sub 2} interface. This suggests that the electronic structures of the a-IGZO bulk strongly affected the thin-film transistor characteristics. The results of XANES indicated an increase in the number of tail states upon atmospheric annealing (AT). We consider that the increase in the number of tail states decreased the channel mobility of AT samples.

Ueoka, Y.; Ishikawa, Y.; Maejima, N.; Matsui, F.; Matsui, H.; Yamazaki, H.; Urakawa, S.; Horita, M.; Daimon, H.; Uraoka, Y. [Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan)] [Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192 (Japan)

2013-10-28

93

Analysis of electronic structure of amorphous InGaZnO/SiO2 interface by angle-resolved X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

The electronic structures of amorphous indium gallium zinc oxide (a-IGZO) on a SiO2 layers before and after annealing were observed by constant final state X-ray photoelectron spectroscopy (CFS-XPS) and X-ray adsorption near-edge structure spectroscopy (XANES). From the results of angle-resolved CFS-XPS, the change in the electronic state was clearly observed in the a-IGZO bulk rather than in the a-IGZO/SiO2 interface. This suggests that the electronic structures of the a-IGZO bulk strongly affected the thin-film transistor characteristics. The results of XANES indicated an increase in the number of tail states upon atmospheric annealing (AT). We consider that the increase in the number of tail states decreased the channel mobility of AT samples.

Ueoka, Y.; Ishikawa, Y.; Maejima, N.; Matsui, F.; Matsui, H.; Yamazaki, H.; Urakawa, S.; Horita, M.; Daimon, H.; Uraoka, Y.

2013-10-01

94

OSO-8 soft X-ray wheel experiment: Data analysis  

NASA Technical Reports Server (NTRS)

The soft X-ray experiment hardware and its operation are described. The device included six X-ray proportional counters, two of which, numbers 1 and 4, were pressurized with on-board methane gas supplies. Number 4 developed an excessive leak rate early in the mission and was turned off on 1975 day number 282 except for brief (typically 2-hour) periods up to day 585 after which it as left off. Counter 1 worked satisfactorily until 1975 day number 1095 (January 1, 1978) at which time the on-board methane supply was depleted. The other four counters were sealed and all except number 3 worked satisfactorily throughout the mission which terminated with permanent satellie shut-down on day 1369. This was the first large area thin-window, gas-flow X-ray detector to be flown in orbit. The background problems were severe and consumed a very large portion of the data analysis effort. These background problems were associated with the Earth's trapped electron belts.

Kraushaar, W. L.

1982-01-01

95

Search for X-rays and relativistic electrons in laboratory discharge experiments  

NASA Astrophysics Data System (ADS)

In 2013 discharge experiments were carried out at the Technical University of Eindhoven. The experimental set-up was designed to search for both X-rays and electrons produced in meter-scale sparks using a 1 MV Marx generator. In this paper we present the spatial distribution of signals and examine whether they are X-rays only or X-rays and electrons. Other characteristics of the signals will be presented as well. These experiments are carried out in the context of a larger effort to understand the various phenomena of X-rays and gammas from natural lightning. We acknowledge Z. Scherrer, K. Weber and K. LeCaptain at the Carthage college for supporting the initial data-analysis.

Ostgaard, Nikolai; Carlson, Brant E.; Grøndahl, Øystein; Kochkin, Pavlo; Nisi, Ragnhild S.; Gjesteland, Thomas

2014-05-01

96

X-Ray Diffraction Analysis Program  

NASA Technical Reports Server (NTRS)

SOPAD separates overlapping peaks and analyzes derivatives of X-ray diffraction data. SOPAD helps analyst get most information out of available diffraction data. SOPAD uses Marquardt-type nonlinear regression routine to refine initial estimates of individual peak positions, intensities, shapes, and half-widths.

Wiedemann, K. E.; Unnam, J.; Naidu, S. V. N.; Houska, C. R.

1986-01-01

97

Fundamental physics at an X-ray free electron laser  

Microsoft Academic Search

X-ray free electron lasers (FELs) have been proposed to be constructed both at SLAC in the form of the so-called Linac Coherent Light Source as well as at DESY, where the so-called XFEL laboratory is part of the design of the electron-positron linear collider TESLA. In addition to the immediate applications in condensed matter physics, chemistry, material science, and structural

A. Ringwald

2001-01-01

98

Interaction of relativistic electrons with ultrashort laser pulses: Generation of femtosecond x-rays and microprobing of electron beams  

SciTech Connect

The interaction of relativistic electrons with terawatt femtosecond laser pulses is reviewed with emphasis on how the scattering process can be used as a source of ultrashort X-ray pulses and as a time-resolved diagnostic for measuring transverse and longitudinal phase space distributions of an electron beam with microns spatial and subpicosecond temporal resolution. Recent experimental results are presented in which 90{degree} Thomson scattering was utilized to generate 300 fs duration pulses of X-rays with peak energy of 30 keV. It is shown that, through analysis of the scattered X-ray beam properties, transverse and longitudinal distributions of the electron beam can be obtained.

Leemans, W.P.; Schoenlein, R.W.; Volfbeyn, P. [Lawrence Berkeley National Lab., CA (United States)] [and others] [Lawrence Berkeley National Lab., CA (United States); and others

1997-11-01

99

SEM/X-ray imaging method in petrographic modal analysis  

SciTech Connect

Image analysis is a fast and accurate technique for conducting petrographic modal analysis. In a routine scanning electron microscope-based modal analysis, backscattered electrons (BSE) are used to generate atomic number contrast to determine the presence of various minerals. The minerals are then identified with the use of an energy-dispersive spectrometer. The number of pixels, displayed as a specific level of intensity for a particular mineral, can be integrated and then calculated into the modal percent of that mineral. This method works well in most cases except where samples contain minerals with similar average atomic numbers or backscattering coefficients, thus producing ambiguity in identifying minerals in the BSE image. This problem, however, can be overcome by using a superimposed x-ray imaging method (SXI), which applies logic and function to combine multiple x-ray maps of various elements in a mineral. The area of each mineral can then be estimated by integrating the pixels which contain all characteristic elements for that mineral. If two or more minerals contain the same elements but different concentrations, the minerals can be distinguished by the pixel intensity in the x-ray maps. An application of the SXI method on a sample consisting of quartz, albite, and orthoclase proves that this method can unambiguously identify minerals and provide modal analysis with an absolute percent error of less than 2%. In contrast, the use of the BSE method creates difficulty in distinguishing quartz from albite owing to the close backscattering coefficients (quartz 0.125 vs albite 0.124). Therefore, the author recommends that the SXI method be incorporated with the routine BSE method for an accurate modal analysis.

Liang, L.

1989-03-01

100

Analysis of particles produced during airbag deployment by scanning electron microscopy with energy dispersive x-ray spectroscopy and their deposition on surrounding surfaces: a mid-research summary  

Microsoft Academic Search

Airbags can be encountered in forensic work when investigating a car crash and are typically constructed with primerlike material to begin the deployment apparatus. The mechanisms of airbag deployment can produce particles ideal for scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM\\/EDS) analysis. A recent study published by Berk studied airbags with vents and showed that it is possible

J. Matney Wyatt

2011-01-01

101

NASA Li/CF(X) Cell Problem Analysis: Scanning Electron Microscopy with Energy Dispersive X Ray Spectrometry.  

National Technical Information Service (NTIS)

An analysis was made of Lithium/carbon fluoride cell parts for possible chloride contamination induced by exposure to thionyl chloride (SOCl2); various samples were submitted for analysis. Only a portion of the analysis which has been conducted is covered...

J. Baker

1991-01-01

102

Correlative Instrumental Neutron Activation Analysis, Light Microscopy, Transmission Electron Microscopy, and X-ray Microanalysis for Qualitative and Quantitative Detection of Colloidal Gold Spheres in Biological Specimens.  

PubMed

: Colloidal gold, conjugated to ligands or antibodies, is routinely used as a label for the detection of cell structures by light (LM) and electron microscopy (EM). To date, several methods to count the number of colloidal gold labels have been employed with limited success. Instrumental neutron activation analysis (INAA), a physical method for the analysis of the elemental composition of materials, can be used to provide a quantitative index of gold accumulation in bulk specimens. Given that gold is not naturally found in biological specimens in any substantial amount and that colloidal gold and ligand conjugates can be prepared to yield uniform bead sizes, the amount of label can be calculated in bulk biological samples by INAA. Here we describe the use of INAA, LM, transmission EM, and X-ray microanalysis (EDX) in a model to determine both distribution (localization) and amount of colloidal gold at the organ, tissue, cellular, and ultrastructural levels in whole animal systems following administration. In addition, the sensitivity for gold in biological specimens by INAA is compared with that of inductively coupled plasma-mass spectrometry (ICP-MS). The correlative use of INAA, LM, TEM, and EDX can be useful, for example, in the quantitative and qualitative tracking of various labeled molecular species following administration in vivo. PMID:9990870

Hillyer; Albrecht

1998-09-01

103

Three-Dimensional X-ray Observation of Atmospheric Biological Samples by Linear-Array Scanning-Electron Generation X-ray Microscope System  

Microsoft Academic Search

Recently, we developed a soft X-ray microscope called the scanning-electron generation X-ray microscope (SGXM), which consists of a simple X-ray detection system that detects X-rays emitted from the interaction between a scanning electron beam (EB) and the thin film of the sample mount. We present herein a three-dimensional (3D) X-ray detection system that is based on the SGXM technology and

Toshihiko Ogura; Akos Vertes

2011-01-01

104

Pulse height analysis using Si-pin diode of x-ray irradiated from a 2.45 GHz electron cyclotron resonance multicharged ion source  

NASA Astrophysics Data System (ADS)

Production of multicharged ions is experimentally studied on an electron cyclotron resonance (ECR) source. The ECR zone for a microwave frequency of 2.45 GHz is formed at the bottom of a mirror trap. The x-ray spectra are measured by Si-pin diode detector in the various operating conditions. Available energy range of the x-ray measurement is several keV approximately several tens keV. Measurements are carried out at either line of sight including the ECR zone along the geometrical axis or at off-ECR zone from the side wall. The temperatures determined at both positions are about 2-3 keV from the observed spectrum with assuming nonrelativistic maxwellian plasma. The intensities of Ar K? and bremsstrahlung radiation correlate to pressure and microwave power dependence of multicharged-ion production. But the dependence of the temperature is not clear. Therefore the multicharged-ion production largely depends on an abundance of high energy electrons rather than the change of the temperature of them in this energy region; and it is suggested that the emission profiles of the x-ray radiation peaks at the center of the mirror at the low pressure.

Kato, Yushi; Kubo, Yoshiyuki; Ishii, Shigeyuki

1998-02-01

105

A case of hut lung: scanning electron microscopy with energy dispersive x-ray spectroscopy analysis of a domestically acquired form of pneumoconiosis.  

PubMed

Hut lung is a pneumoconiosis caused by exposure to smoke derived from biomass fuels used for cooking in poorly ventilated huts. We report, to our knowledge, the first analysis of the dust deposited in the lungs in hut lung by scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM/EDS). A Bhutanese woman presented with shortness of breath and an abnormal chest radiograph. Chest CT scan showed innumerable tiny bilateral upper lobe centrilobular nodules. Transbronchial biopsy revealed mild interstitial fibrosis with heavy interstitial deposition of black dust. SEM/EDS showed that the dust was carbonaceous, with smaller yet substantial numbers of silica and silicate particles. Additional history revealed use of a wood/coal-fueled stove in a small, poorly ventilated hut for 45 years. The possibility of hut lung should be considered in women from countries where use of biomass-fueled stoves for cooking is common. Our findings support the classification of this condition as a mixed-dust pneumoconiosis. PMID:23880681

Mukhopadhyay, Sanjay; Gujral, Manmeet; Abraham, Jerrold L; Scalzetti, Ernest M; Iannuzzi, Michael C

2013-07-01

106

Atomic holography with electrons and x-rays  

SciTech Connect

Gabor first proposed holography in 1948 as a means to experimentally record the amplitude and phase of scattered wavefronts, relative to a direct unscattered wave, and to use such a {open_quotes}hologram{close_quotes} to directly image atomic structure. But imaging at atomic resolution has not yet been possible in the way he proposed. Much more recently, Sz{umlt o}ke in 1986 noted that photoexcited atoms can emit photoelectron or fluorescent x-ray wavefronts that are scattered by neighboring atoms, thus yielding the direct and scattered wavefronts as detected in the far field that can then be interpreted as holographic in nature. By now, several algorithms for directly reconstructing three-dimensional atomic images from electron holograms have been proposed (e.g. by Barton) and successfully tested against experiment and theory. Very recently, Tegze and Faigel, and Gog {ital et al.} have recorded experimental x-ray fluorescence holograms, and these are found to yield atomic images that are more free of the kinds of aberrations caused by the non-ideal emission or scattering of electrons. The basic principles of these holographic atomic imaging methods are reviewed, including illustrative applications of the reconstruction algorithms to both theoretical and experimental electron and x-ray holograms. We also discuss the prospects and limitations of these newly emerging atomic structural probes. {copyright} {ital 1997 American Institute of Physics.}

Len, P.M. [Department of Physics, University of California, Davis, California 95616 (United States of America); Fadley, C.S. [Department of Physics, University of California, Davis, California 95616 (United States of America)]|[Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States of America); Materlik, G. [Hamburger Synchrotronstrahlungslabor (HASYLAB) am Deutsches Elektronen-Synchrotron (DESY), 22603 Hamburg (Germany)

1997-01-01

107

The effect of phytostabilization on Zn speciation in a dredged contaminated sediment using scanning electron microscopy, X-ray fluorescence, EXAFS spectroscopy, and principal components analysis  

NASA Astrophysics Data System (ADS)

The maintenance of waterways generates large amounts of dredged sediments, which are deposited on adjacent land surfaces. These sediments are often rich in metal contaminants and present a risk to the local environment. Understanding how the metals are immobilized at the molecular level is critical for formulating effective metal containment strategies such as phytoremediation. In the present work, the mineralogical transformations of Zn-containing phases induced by two graminaceous plants (A grostis tenuis and Festuca rubra) in a contaminated sediment ([Zn] = 4700 mg kg -1, [P 2O 5] = 7000 mg kg -1, pH = 7.8), untreated or amended with hydroxylapatite (AP) or Thomas basic slag (TS), were investigated after two yr of pot experiment by scanning electron microscopy coupled with energy-dispersive spectrometry (SEM-EDS), synchrotron-based X-ray microfluorescence (?-SXRF), and powder and laterally resolved extended X-ray absorption fine structure (?-EXAFS) spectroscopy. The number and nature of Zn species were evaluated by principal component (PCA) and least-squares fitting (LSF) analysis of the entire set of ?-EXAFS spectra, which included up to 32 individual spectra from regions of interest varying in chemical composition. Seven Zn species were identified at the micrometer scale: sphalerite, gahnite, franklinite, Zn-containing ferrihydrite and phosphate, (Zn-Al)-hydrotalcite, and Zn-substituted kerolite-like trioctahedral phyllosilicate. Bulk fractions of each species were quantified by LSF of the powder EXAFS spectra to linear combinations of the identified Zn species spectra. In the untreated and unvegetated sediment, Zn was distributed as ˜50% (mole ratio of total Zn) sphalerite, ˜40% Zn-ferrihydrite, and ˜10 to 20% (Zn-Al)-hydrotalcite plus Zn-phyllosilicate. In unvegetated but amended sediments (AP and TS), ZnS and Zn-ferrihydrite each decreased by 10 to 20% and were replaced by Zn-phosphate (˜30˜40%). In the presence of plants, ZnS was almost completely dissolved, and the released Zn bound to phosphate (˜40-60%) and to Zn phyllosilicate plus (Zn,Al)-hydrotalcite (˜20-40%). Neither the plant species nor the coaddition of mineral amendment affected the Zn speciation in the vegetated sediment. The sediment pore waters were supersaturated with respect to Zn-containing trioctahedral phyllosilicate, near saturation with respect to Zn-phosphate, and strongly undersaturated with respect to (Zn,Al)-hydrotalcite. Therefore, the formation of (Zn,Al)-hydrotalcite in slightly alkaline conditions ought to result from heterogeneous precipitation on mineral surface.

Panfili, Frédéric; Manceau, Alain; Sarret, Géraldine; Spadini, Lorenzo; Kirpichtchikova, Tatiana; Bert, Valérie; Laboudigue, Agnès; Marcus, Matthew A.; Ahamdach, Noureddine; Libert, Marie-Françoise

2005-05-01

108

Electron Microscopy and X-ray Analysis of Cr-Containing Precipitates Synthesized by Newly Isolated Actinobacterium, Flexivirga alba ST13(T.).  

PubMed

Chromium(Cr) precipitate synthesized by Cr(VI)-reducing bacterium Flexivirga alba ST13(T) was examined using transmission electron microscopy (TEM) and the energy dispersive X-ray (EDX). The strain showed altered-morphology after exposing to Cr(VI) in minimal medium. The resultant precipitate included bacterial pellet and needle-like structure which was similar to the structure made from Cr(OH)3 precipitate. Cr was observed in bacterial cells using TEM-EDX. Bacteria with high electron density showed the precipitation of Ca in addition to Cr. The isolated strain would be useful to precipitate Cr from Cr(VI)-containing environment. PMID:24891744

Sugiyama, Tomoyasu; Sakaguchi, Toshifumi

2014-09-01

109

Aerosols over the Amazon Rainforest Investigated by Scanning Transmission X-ray Microscopy and Scanning Electron Microscopy  

Microsoft Academic Search

We collected atmospheric aerosols over the central Amazon Basin near Manaus, Brazil, during the wet season in February 2008, as part of the AMAZE-08 (Amazonian Aerosol Characterization Experiment) campaign. Aerosol samples were analyzed by Scanning Transmission X-ray Microscopy (STXM) coupled with Near-Edge X-ray Absorption Fine Structure Spectroscopy (NEXAFS) and Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive X-ray Analysis (EDX). A

M. O. Andreae; P. P. Artaxo; M. K. Gilles; S. T. Martin; E. Mikhailov; R. Moffet; U. Poeschl; B. Sinha; H. Yang

2009-01-01

110

X ray microscope assembly and alignment support and advanced x ray microscope design and analysis  

NASA Technical Reports Server (NTRS)

Considerable efforts have been devoted recently to the design, analysis, fabrication, and testing of spherical Schwarzschild microscopes for soft x ray application in microscopy and projection lithography. The spherical Schwarzschild microscope consists of two concentric spherical mirrors configured such that the third order spherical aberration and coma are zero. Since multilayers are used on the mirror substrates for x ray applications, it is desirable to have only two reflecting surfaces in a microscope. In order to reduce microscope aberrations and increase the field of view, generalized mirror surface profiles have been considered in this investigation. Based on incoherent and sine wave modulation transfer function (MTF) calculations, the object plane resolution of a microscope has been analyzed as a function of the object height and numerical aperture (NA) of the primary for several spherical Schwarzschild, conic, and aspherical head reflecting two mirror microscope configurations.

Shealy, David L.

1991-01-01

111

X-ray induced electron emission. Final report  

SciTech Connect

The development and use of a magnetic spectrograph for the measurement of X-ray induced electron emission is described. Results are presented for metal and dielectric targets ranging in atomic number from Z=6 to Z-82. Materials studied were lead, tantalum, copper, aluminum, magnesium, solar cell cover glass, silica cloth, thermal control paint, Kevlar, Mylar, and conducting/nonconducting epoxy. Direct measurement was made of the quantum yield and energy distribution of electrons emitted at angles of 0 deg, 30 deg, 45 deg and 60 deg with respect to the surface normal of targets exposed to normal incidence filtered and unfiltered 50kV bremsstrah lung X-rays. Experimental results are compared with previous measurements where possible, and with computer code predictions where predictive capability matches the measurement range. The experimental results corroborates the cos theta angular dependence predicted by simple theoretical models, particularly for medium and high Z materials. A trend toward isotropic emission distribution is noted for the lower Z materials. Compared to the measured results, the emission yields predicted by a commonly used analytical model are low by approximately a factor of 2 for the unfiltered X-ray spectrum.

Aeby, C.A.

1982-04-01

112

Femtosecond X-ray absorption spectroscopy at a hard X-ray free electron laser: application to spin crossover dynamics.  

PubMed

X-ray free electron lasers (XFELs) deliver short (<100 fs) and intense (?10(12) photons) pulses of hard X-rays, making them excellent sources for time-resolved studies. Here we show that, despite the inherent instabilities of current (SASE based) XFELs, they can be used for measuring high-quality X-ray absorption data and we report femtosecond time-resolved X-ray absorption near-edge spectroscopy (XANES) measurements of a spin-crossover system, iron(II) tris(2,2'-bipyridine) in water. The data indicate that the low-spin to high-spin transition can be modeled by single-exponential kinetics convoluted with the overall time resolution. The resulting time constant is ?160 fs. PMID:23281652

Lemke, Henrik T; Bressler, Christian; Chen, Lin X; Fritz, David M; Gaffney, Kelly J; Galler, Andreas; Gawelda, Wojciech; Haldrup, Kristoffer; Hartsock, Robert W; Ihee, Hyotcherl; Kim, Jeongho; Kim, Kyung Hwan; Lee, Jae Hyuk; Nielsen, Martin M; Stickrath, Andrew B; Zhang, Wenkai; Zhu, Diling; Cammarata, Marco

2013-01-31

113

Note: Studies on x-ray production in electron cyclotron resonance x-ray source based on ridged cylindrical cavity  

SciTech Connect

A ridged cylindrical cavity has been designed using MICROWAVE STUDIO programme and it is used in the electron cyclotron resonance (ECR) x-ray source. The experimental parameters of the source are optimized for maximizing the x-ray output, and an x-ray dose rate of {approx}1000 {mu}Sv/h was observed at 20 cm from the port, for 500 W of microwave power without using any target. With the molybdenum target located at optimum position of the ridged cavity, the dose rate is found to be increased only by 10%. In order to understand the experimental observation, the electric field pattern of the cavity with the target placed at various radial distances is studied. In this note, the experimental and theoretical studies on ECR x-ray source using the ridged cylindrical cavity are presented.

Selvakumaran, T. S.; Baskaran, R. [Radiological Safety Division, Indira Gandhi Center for Atomic Research, Kalpakkam, Tamilnadu 603102 (India)

2012-02-15

114

X-ray optics power considerations for high intensity x-ray free-electron lasers based on superconducting technology  

NASA Astrophysics Data System (ADS)

X-ray free-electron lasers generate ultrashort and very intense x-ray radiation in the wavelength domain reaching from the VUV (100 nm and shorter) all the way to the hard x-ray domain (typically 0.1 nm). FEL radiation features extreme brilliance, ultrashort pulse duration, and high peak power. Superconducting accelerators provide furthermore the possibility to accelerate a large number of electron bunches during a single radio-frequency pulse. Likewise the total number of x-ray pulses available for the experiments is increased leading to a significantly higher average brilliance. FEL light sources, and those based on super-conducting accelerator technology, are therefore considered to provide a new quality of short wavelength radiation if compared to existing x-ray sources. The high intensity and the high repetition rate lead to new requirements for x-ray optics in terms of peak and average power. Values for peak and average power are presented in relation to the proposed realization of the photon beamlines at the European XFEL facility.

Tschentscher, Th.; Sinn, H.; Tiedtke, K.; Wabnitz, H.

2007-05-01

115

The angular distribution of energetic electron and X-ray emissions from triggered lightning leaders  

NASA Astrophysics Data System (ADS)

We investigate individual X-ray bursts from lightning leaders to determine if energetic electrons at the source (and hence X-rays) are emitted isotropically or with some degree of anisotropy. This study was motivated by the work of Saleh et al. (2009), which found the falloff of X-rays in concentric radial annuli, covering all azimuthal directions in each annulus, from the lightning channel to be most consistent with an isotropic electron source. Here we perform a statistical analysis of angular and spatial distributions of X-rays measured by up to 21 NaI/PMT detectors at the International Center for Lightning Research and Testing site for 21 leader X-ray bursts from five leaders (including four dart-stepped leaders and one dart leader). Two procedures were used to complete this analysis. Procedure 1 found the first-order anisotropy, and procedure 2 tested whether or not the angular distribution was consistent with an isotropic distribution. Because higher-order anisotropies could be present in the data, a distribution that is not isotropic does not necessarily have a significant first-order anisotropy. Using these procedures, we find that at least 11 out of 21 X-ray bursts have a statistically significant first-order anisotropy, and hence those 11 are inconsistent with an isotropic emission. The remaining 10 bursts do not have significant first-order anisotropy. However, of those 10 bursts, 9 are inconsistent with isotropic emission, since they exhibit significant higher-order anisotropies. Since Saleh et al. (2009) did not consider anisotropies in the azimuthal direction, these new measurements of anisotropy do not necessarily contradict that work. Indeed, our analysis supports the finding that the X-ray emissions from lightning are inconsistent with a vertically downward beam. The level of anisotropy of the runaway electrons is important because it provides, in principle, information on the streamer zone in front of the leader and the electric field near the lightning leader tip.

Schaal, M. M.; Dwyer, J. R.; Rassoul, H. K.; Hill, J. D.; Jordan, D. M.; Uman, M. A.

2013-10-01

116

X-ray surveys - X-ray spectral analysis of bright Chandra-COSMOS sources  

NASA Astrophysics Data System (ADS)

We present the X-ray spectral analysis of the 405 brightest sources in the Chandra- COSMOS catalog (Elvis et al. 2009) that present at least 70 net counts in the 0.5-7 keV band. This bright sample has a ~100% completeness in optical-IR identification, with ~73% of the sample having a spectroscopic redshift and ~23% a photometric redshift (with accuracy ?(z)/(1+z)~1.5%). This allow us to accurately determine both the intrinsic absorption distribution and the intrinsic L2-10 of all the sources in the sample, and to study the evolution of X-ray spectral parameters in redshift. We analyze the statistical distribution of X-ray spectral properties in the sample (e.g. NH and L2-10 distribution, fraction of obscured sources) and their correlation with multiwavelength properties. Finally, 294 sources present a detected counterpart in the XMM-COSMOS survey. For this sources we performed a simultaneous spectral fit with the XMM-Newton data, in order to search for systematic differences in the constraint on spectral parameters and, eventually, for variability in the values of flux and obscuration.

Lanzuisi, Giorgio

2012-09-01

117

X-Ray diffraction and scanning electron microscopy-energy dispersive spectroscopic analysis of ceram?metal interface at different firing temperatures  

PubMed Central

Objective: Porcelain chipping from porcelain fused to metal restoration has been Achilles heel till date. There has been advent of newer ceramics in past but but none of them has been a panacea for Porcelain fracture. An optimal firing is thus essential for the clinical success of the porcelain-fused to metal restoration. The aim of the present study was to evaluate ceramo-metal interface at different firing temperature using XRD and SEM-EDS analysis. Clinical implication of the study was to predict the optimal firing temperature at which porcelain should be fused with metal in order to possibly prevent the occasional failure of the porcelain fused to metal restorations. Materials and Methods: To meet the above-mentioned goal, porcelain was fused to metal at different firing temperatures (930–990°C) in vacuum. The microstructural observations of interface between porcelain and metal were evaluated using X-ray diffraction and scanning electron microscopy with energy dispersive spectroscopy. Results: Based on the experimental investigation of the interaction zone of porcelain fused to metal samples, it was observed that as the firing temperature was increased, the pores became less in number as well as the size of the pores decreased at the porcelain/metal interface upto 975°C but increased in size at 990°C. The least number of pores with least diameter were found in samples fired at 975°C. Several oxides like Cr2O3, NiO, and Al2O3 and intermetallic compounds (CrSi2, AlNi3) were also formed in the interaction zone. Conclusions It is suggested that the presence of pores may trigger the crack propagation along the interface, causing the failure of the porcelain fused to metal restoration during masticatory action.

Saini, Monika; Chandra, Suresh; Singh, Yashpal; Basu, Bikramjit; Tripathi, Arvind

2010-01-01

118

Basic studies on x-ray fluorescence analysis for active x-ray spectrometer on SELENE-2  

NASA Astrophysics Data System (ADS)

An active X-ray spectrometer (AXS) is now being developed as a payload candidate for the rover on SELENE-2, the next Japanese lunar exploration mission. The AXS will determine the chemical compositions of lunar rocks and regolith around the landing site. The surface of lunar rock samples will be ground using a rock abrasion tool. Thus, fundamental studies on the X-ray fluorescence analysis for lunar rocks and regolith are required to design and develop the AXS. In this study, we have investigated the X-ray fluorescence analysis in order to evaluate the effects of surface roughness of samples and the angle of incident and emergent X-rays. It was found that the fluorescent X-ray yield for low energy X-rays, i.e. the light elements, decreases at rough surface samples. This effect of surface roughness becomes small for smooth surface samples. It was also found that the fluorescent X-ray yield depends on the incident angle, which is attributed to the fact that the X-ray fluorescence occurs closer to the sample surface at larger incident angles. Since the emergent X-rays are affected by the detection geometry and surface roughness, the incident angle effect also depends on the above conditions.

Kusano, Hiroki; Hasebe, Nobuyuki; Nagaoka, Hiroshi; Kodama, Takuro; Oyama, Yuki; Tanaka, Reiko; Amano, Yoshiharu; Kim, Kyeong J.; Matias Lopes, Josè A.

2013-09-01

119

University of California electron and X-ray experiments on ISEE-3  

NASA Technical Reports Server (NTRS)

The history of the University of California solar and interplanetary electron experiment and the solar X-ray experiment is outlined, and the two instruments used are described. The roles of personnel are mentioned and the data analysis projects completed or begun are summarized. A bibliography is included.

Anderson, K. A.

1981-01-01

120

A new soft x-ray pulse height analysis array in the HL-2A tokamak  

SciTech Connect

A new soft x-ray pulse height analysis (PHA) array including nine independent subsystems, on basis of a nonconventional software multichannel analysis system and a silicon drift detector (SDD) linear array consisting of nine high performance SDD detectors, has been developed in the HL-2A tokamak. The use of SDD has greatly improved the measurement accuracy and the spatiotemporal resolutions of the soft x-ray PHA system. Since the ratio of peak to background counts obtained from the SDD PHA system is very high, p/b{>=}3000, the soft x-ray spectra measured by the SDD PHA system can approximatively be regarded as electron velocity distribution. The electron velocity distribution can be well derived in the pure ohmic and auxiliary heating discharges. The performance of the new soft x-ray PHA array and the first experimental results with some discussions are presented.

Zhang, Y. P.; Liu Yi; Yang, J. W.; Song, X. Y.; Liao, M.; Li, X.; Yuan, G. L.; Yang, Q. W.; Duan, X. R.; Pan, C. H. [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041 (China)

2009-12-15

121

An X-ray luminosity analysis for FRIs and FRIIs  

NASA Astrophysics Data System (ADS)

Radio galaxies are divided into two groups according to their luminosities at 178 MHz, namely Fanaroff-Riley type Is (FRIs) and Fanaroff-Riley type IIs (FRIIs) with FRIs showing lower radio luminosities than FRIIs. In this paper, the X-ray data are compiled for 183 radio galaxies (61 FRIs and 122 FRIIs), from the available literature, for the analysis of the X-ray properties. The 1 keV X-ray luminosities are calculated and discussed for the two groups, and an averaged X-ray luminosity of log L {X/1 keV} = 41.30±2.51 erg·s-1·keV-1 is found for FRIs, which is lower than that for FRIIs, log L {X/1 keV} = 43.39±3.06 erg·s-1·keV-1. A Kolmogorov-Smirnov (K-S) test indicates that the probability for the X-ray luminosity distributions of the two groups to be from the same parent distribution is 1.44×10-10. We also discuss the origin and the mechanism of the X-ray emission for FRIs and FRIIs.

Zhang, Chunling; Fan, Junhui

2009-09-01

122

Characterization of a femtosecond-laser-produced plasma x-ray source by electronic, optical, and x-ray diagnostic techniques  

NASA Astrophysics Data System (ADS)

Short-pulse laser-produced plasmas look very promising for the generation of sub-picosecond X-rays. By combining several experimental techniques, we have significantly progressed towards a better understanding of ultrafast laser-matter interaction. The X-ray yield is a sensitive function of the electron density gradient scale length of the target plasma. In this work, the scale length has been changed by varying the temporal separation between the main laser pulse and a lower intensity prepulse. X-ray spectroscopic diagnostics of the plasma parameters have been used from the analysis of resonance and dielectronic satellite lines. The angular and energy distribution of suprathermal electrons emitted during the ultrafast laser- plasma interaction have been measured as a function of laser polarization and prepulse delay. Frequency-domain interferometry and optical measurements of the reflected probe pulse have been used to study the velocity and the gradient scale length of the expanding plasma. The K? emission yield peaks for a scale length where resonant absorption is optimized. Hydrodynamic simulations have been performed to investigate the plasma dynamics and the basic processes which control the X-ray emission duration and intensity. Applications of ultrashort K? X-rays to the diagnostic of solid plasma conditions and as a source for time-resolved diffraction and spectroscopy of transient chemical, biological or physical phenomena are underway.

Gauthier, Jean-Claude J.; Bastiani, S.; Audebert, Patrick; Geindre, Jean-Paul; Rousse, Antoine; Quoix, C.; Grillon, G.; Mysyrowicz, Andre; Antonetti, Andre; Mancini, Roberto C.; Shlyaptseva, Alla S.

1997-10-01

123

Limitations of ZAF correction factors in the determination of calcium\\/phosphorus ratios: Important forensic science considerations relevant to the analysis of bone fragments using scanning electron microscopy and energy-dispersive x-ray microanalysis  

Microsoft Academic Search

A series of calcium phosphate standards having calcium\\/phosphorus (Ca\\/P) molar ratios of 0.50, 1.00, 1.50, and 1.67, respectively, was prepared for bulk specimen analysis using scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDXA). The standards were mounted on carbon planchettes as either pure crystals or crystals embedded in epoxy resin. Ten different samples of each embedded and non-embedded standard

C. M. Payne; D. W. Cromey

1990-01-01

124

Three-Dimensional Analysis of Urban Aerosols by use of a Combined Lidar, Scanning Electron Microscopy, and X-Ray Microanalysis.  

PubMed

We present a novel method of characterizing urban aerosols that combines scanning-electron microscopy, x-ray microanalysis, and lidar measurements. Inversion algorithms, based on fractal aerosol models, allowed us to compute the scattering coefficients of the measured size distribution. The alpha and beta coefficients were used to invert lidar data, yielding what to our knowledge are the first quantitative three-dimensional measurements of the aerosol mass concentrations in urban conditions. The combined method was used during an extensive experiment in Lyon in the summer of 1996. Size distributions exhibit two main modes, at 0.1 and 0.9 mum, the composition of which was determined by x-ray microanalysis. The first mode is soot, and the second is composed of 60% coarse soot particles and 40% silica particles. Lidar measurements showed a homogeneous aerosol concentration within the mixing layer and a steep gradient above. Measurements made over 24 h also showed loads that were due to traffic rush hours and the dynamics of the height of the planetary boundary layer. PMID:18273146

Frejafon, E; Kasparian, J; Rambaldi, P; Yu, J; Vezin, B; Wolf, J P

1998-04-20

125

Analysis of paramagnetic centers in X-ray-irradiated enamel, bone, and carbonate-containing hydroxyapatite by electron spin resonance spectroscopy.  

PubMed

Carbonate-containing hydroxyapatite, enamel, and bone were irradiated by an X-ray and investigated between 77 degrees and 350 degrees K by means of electron spin resonance (ESR) spectroscopy. The ESR spectrum of enamel irradiated at 77 degrees K in vacuum and observed at the same temperature was almost the same as that of the carbonate-containing hydroxyapatite. The temperature dependence of signal intensities confirms a spin-energy exchange between the mineral and organic constituents in bone, but in enamel no or very little spin-energy exchange between the mineral and organic constituents. Considerable similarity among the ESR spectra of enamel, bone, and carbonate-containing apatite was obtained after X-ray irradiation in air at 300 degrees K with both an X-band and a Q-band ESR spectrometer. The Q-band spectrum can be interpreted in terms of two paramagnetic species. One is identified as a CO3(3-) anion radical which has an axial symmetry with g factors of 2.0029 and 1.9972. The other species is found to be centered at g = 2.0019. PMID:228815

Doi, Y; Aoba, T; Okazaki, M; Takahashi, J; Moriwaki, Y

1979-10-31

126

Hard x-ray or gamma ray laser by a dense electron beam  

SciTech Connect

A dense electron beam propagating through a laser undulator can radiate a coherent x-ray or gamma ray. This lasing scheme is studied with the Landau damping theory. The analysis suggests that, with currently available physical parameters, coherent gamma rays of up to 50 keV can be generated. The electron quantum diffraction suppresses the free electron laser action, which limits the maximum radiation.

Son, S. [18 Caleb Lane, Princeton, New Jersey 08540 (United States); Joon Moon, Sung [8 Benjamin Rush Ln., Princeton, New Jersey 08540 (United States)

2012-06-15

127

Food Irradiation Using Electron Beams and X-Rays  

NASA Astrophysics Data System (ADS)

In this presentation we will discuss the technology of food irradiation using electron accelerators. Food irradiation has generally come to describe the use of ionizing radiation to decrease the population of, or prevent the growth of, undesirable biological organisms in food. The many beneficial applications include insect disinfestation, sprouting inhibition, delayed ripening, and the enhanced safety and sterilization of fresh and frozen meat products, seafood, and eggs. With special regard to food safety, bacteria such as Salmonella enteridis, Listeria monocytogenes, Campylobacter jejuni and Escherichia coli serotype O157:H7 are the primary causes of food poisoning in industrialized countries. Ionizing doses in the range of only 1-5 kilogray (kGy) can virtually eliminate these organisms from food, without affecting the food's sensory and nutritional qualities, and without inducing radioactivity. The key elements of an accelerator-based irradiation facility include the accelerator system, a scanning system, and a material handling system that moves the product through the beam in a precisely controlled manner. Extensive radiation shielding is necessary to reduce the external dose to acceptable levels, and a safety system is necessary to prevent accidental exposure of personnel during accelerator operation. Parameters that affect the dose distribution must be continuously monitored and controlled with process control software. The choice of electron beam vs x-ray depends on the areal density (density times thickness) of the product and the anticipated mass throughput. To eliminate nuclear activation concerns, the maximum kinetic energy of the accelerator is limited by regulation to 10 MeV for electron beams, and 5 MeV for x-rays. From penetration considerations, the largest areal density that can be treated by double-sided electron irradiation at 10 MeV is about 8.8 g/cm2. Products having greater areal densities must be processed using more penetrating x-rays. The mass throughput (dM/dt in kg/s) of an accelerator-based system is proportional to the average beam power (P in kW), and inversely proportional to the minimum required dose (Dm in kGy, with 1 kGy = 1 kJ/kg). The constant of proportionality is the mass throughput efficiency. Throughput efficiencies of 0.4 or better are typical of electron beam installations, but are only 0.025-0.035 for x-ray installations, primarily because of the inefficiency of bremsstrahlung generation at 5 MeV (about 8an axially-coupled, standing-wave, L-band linac with an average power in excess of 100 kW to achieve reasonable throughput rates with x-ray processing. Various design aspects of this new machine will be presented.

Miller, Bruce

2003-04-01

128

Miniature, low-power X-ray tube using a microchannel electron generator electron source  

NASA Technical Reports Server (NTRS)

Embodiments of the invention provide a novel, low-power X-ray tube and X-ray generating system. Embodiments of the invention use a multichannel electron generator as the electron source, thereby increasing reliability and decreasing power consumption of the X-ray tube. Unlike tubes using a conventional filament that must be heated by a current power source, embodiments of the invention require only a voltage power source, use very little current, and have no cooling requirements. The microchannel electron generator comprises one or more microchannel plates (MCPs), Each MCP comprises a honeycomb assembly of a plurality of annular components, which may be stacked to increase electron intensity. The multichannel electron generator used enables directional control of electron flow. In addition, the multichannel electron generator used is more robust than conventional filaments, making the resulting X-ray tube very shock and vibration resistant.

Elam, Wm. Timothy (Inventor); Kelliher, Warren C. (Inventor); Hershyn, William (Inventor); DeLong, David P. (Inventor)

2011-01-01

129

Proposal for an x-ray free electron laser oscillator with intermediate energy electron beam.  

PubMed

Harmonic lasing of low-gain free electron laser oscillators has been experimentally demonstrated in the terahertz and infrared regions. Recently, the low-gain oscillator has been reconsidered as a promising candidate for hard x-ray free electron lasers, through the use of high reflectivity, high-resolution x-ray crystals. In this Letter, it is proposed to utilize a crystal-based cavity resonant at a higher harmonic of the undulator radiation, together with phase shifting, to enable harmonic lasing of the x-ray free electron laser oscillator, and hence allow the generation of hard x-ray radiation at a reduced electron beam energy. Results show that fully coherent free electron laser radiation with megawatt peak power, in the spectral region of 10-25 keV, can be generated with a 3.5 GeV electron beam. PMID:22400748

Dai, Jinhua; Deng, Haixiao; Dai, Zhimin

2012-01-20

130

GRB Swift X-ray light curves analysis (Margutti+, 2013)  

NASA Astrophysics Data System (ADS)

We present a comprehensive statistical analysis of Swift X-ray light curves of gamma-ray bursts (GRBs) collecting data from more than 650 GRBs discovered by Swift and other facilities. The unprecedented sample size allows us to constrain the rest-frame X-ray properties of GRBs from a statistical perspective, with particular reference to intrinsic time-scales and the energetics of the different light-curve phases in a common rest-frame 0.3-30keV energy band. Temporal variability episodes are also studied and their properties constrained. Two fundamental questions drive this effort: (i) Does the X-ray emission retain any kind of 'memory' of the prompt ?-ray phase? (ii) Where is the dividing line between long and short GRB X-ray properties? We show that short GRBs decay faster, are less luminous and less energetic than long GRBs in the X-rays, but are interestingly characterized by similar intrinsic absorption. We furthermore reveal the existence of a number of statistically significant relations that link the X-ray to prompt ?-ray parameters in long GRBs; short GRBs are outliers of the majority of these two-parameter relations. However and more importantly, we report on the existence of a universal three-parameter scaling that links the X-ray and the ?-ray energy to the prompt spectral peak energy of both long and short GRBs: EX,iso{prop.to}E1.00+/-0.06?,iso/E0.60+/-0.10pk. (3 data files).

Margutti, R.; Zaninoni, E.; Bernardini, M. G.; Chincarini, G.; Pasotti, F.; Guidorzi, C.; Angelini, L.; Burrows, D. N.; Capalbi, M.; Evans, P. A.; Gehrels, N.; Kennea, J.; Mangano, V.; Moretti, A.; Nousek, J.; Osborne, J. P.; Page, K. L.; Perri, M.; Racusin, J.; Romano, P.; Sbarufatti, B.; Stafford, S.; Stamatikos, M.

2013-11-01

131

Electron-optical recorder for pulse x-ray diagnostics of high-speed processes  

Microsoft Academic Search

At research of high speed gas-dynamic processes x-ray image recording method is widely applied. The informativity of this method is defined by characteristics of the x-ray image formation system, which consists from x-ray or gamma- radiation source and a system of images recording. Application of developed in RFNC VNIIEF electron-optical recorders of the x-ray images has allowed to realize multi-

Vasily V. Burtsev; Sergey E. Elfimov; Yuri M. Makarov; Andrey V. Ryzhkov

1997-01-01

132

X-ray fluorescence analysis of various alloys. Part 1  

SciTech Connect

For a number of years, x-ray fluorescence spectrometry has been used in the Y-12 Plant Laboratory for the analysis of a wide variety of materials. During the past few years, the technique has been applied to the analysis of a large number of experimental alloys. The general procedure consists of the following steps: (1) ignition of the alloy to oxides, (2) addition of suitable internal standards, (3) dissolution of the oxides and internal standards by sodium tetraborate (borax) fusion, (4) casting a pellet from the fusion in a graphite mold (Figure 1), and (5) determination of the major constituents by x-ray fluorescence spectrometry.

Charles, J.W. Jr.; Ferguson, M.R.; Eager, M.H.

1980-02-15

133

X-ray fluorescence analysis major elements in silicate minerals  

SciTech Connect

An automated wavelength-dispersive x-ray fluorescence spectrometer is operational for analysis of major elements in rocks and minerals. Procedures for trace-element analysis are being developed. Sample preparation methods and analytical techniques are similar to those commonly used elsewhere, but data reduction is conducted by the Fundamental Parameters program developed by Criss. Unlike empirically derived calibration curves, this data reduction method considers x-ray absorption and secondary fluorescence, which vary with differences in sample composition. X-ray intensities for each element from several standards are averaged to develop a theoretical standard for comparison with samples of unknown composition. Accurate data for samples with wide compositional ranges result from these data reduction and standardization techniques.

Hagan, R.C.

1982-09-01

134

X-ray fluorescence analysis of various alloys. Part 1  

Microsoft Academic Search

For a number of years, x-ray fluorescence spectrometry has been used in the Y-12 Plant Laboratory for the analysis of a wide variety of materials. During the past few years, the technique has been applied to the analysis of a large number of experimental alloys. The general procedure consists of the following steps: (1) ignition of the alloy to oxides,

J. W. Jr. Charles; M. R. Ferguson; M. H. Eager

1980-01-01

135

Fractal analysis of powder X-ray diffraction patterns  

Microsoft Academic Search

X-ray diffraction (XRD) patterns with broad background are commonly found in the characterization of materials with a certain degree of amorphicity, so the sharp intensity peaks associated with material phases are not well defined. This work used rescaled range (denoted by R\\/S) analysis, a method intended for fractal analysis of noisy signals, to characterize XRD patterns with broad background. It

A. Ortiz-Cruz; C. Santolalla; E. Moreno; J. A. de los Reyes-Heredia; J. Alvarez-Ramirez

136

Electron and proton induced x-ray spectrometry: Two complementary spatially resolved analytical techniques in mineralogy  

Microsoft Academic Search

Spatially resolved quantitative analysis by means of the electron probe micro analyzer (EPMA) is now well-established as a routine analytical method for point chemical analysis of a variety of mineral materials. Modern computer controlled EPMA are most often equipped with wavelength dispersive spectrometers (WDS). Quantitative analysis are generally carried out according to a standard based approached, i.e. the x-ray intensities

G. Remond; C. Gilles; D. Isabelle; C. Choi; M. Azahra; O. Rouer; F. Cesbron

1995-01-01

137

Fourier Analysis and Structure Determination--Part III: X-ray Crystal Structure Analysis.  

ERIC Educational Resources Information Center

Discussed is single crystal X-ray crystal structure analysis. A common link between the NMR imaging and the traditional X-ray crystal structure analysis is reported. Claims that comparisons aid in the understanding of both techniques. (MVL)

Chesick, John P.

1989-01-01

138

X-Ray Free Electron Laser Interaction With Matter  

SciTech Connect

X-ray free electron lasers (XFELs) will enable studying new areas of laser-matter interaction. We summarize the current understanding of the interaction of XFEL pulses with matter and describe some of the simulation approaches that are used to design experiments on future XFEL sources. Modified versions of these models have been successful in guiding and analyzing experiments performed at the extreme-ultraviolet FEL FLASH at wavelengths of 6 nm and longer. For photon energies of several keV, no XFEL-matter interaction experiments have been performed yet but data is anticipated to become available in the near future, which will allow to test our understanding of the interaction physics in this wavelength regime.

Hau-Riege, S

2009-05-12

139

Grazing-exit electron probe X-ray microanalysis (GE-EPMA): Fundamental and applications  

Microsoft Academic Search

Electron probe microanalysis (or Scanning electron microscope-energy dispersive X-ray spectrometry) has been studied under grazing-exit conditions. That is, characteristic X-rays are detected at a very small take-off (exit) angle; the technique is known as grazing-exit electron probe microanalysis (GE-EPMA). Fundamental aspects, instrumentation, and characteristics of grazing-exit electron probe X-ray microanalysis method are described here. Since the observation depth decreases as

Kouichi Tsuji

2005-01-01

140

A model for multi-energy x-ray analysis  

NASA Astrophysics Data System (ADS)

Multi-energy x-ray analysis (MEXA) uses measurements of the x-ray linear attenuation coefficient ?, obtained at different photon energies to determine parameters that characterize the density and composition of materials. The key to achieving this goal is an accurate parameterization for ?, allowing measurements to be written as simultaneous equations and then solved. This author has reported such a model where mixtures are characterized by four or more statistical moments that describe the distribution of atomic number. These can be re-expressed as the product of the electron density Ne and four or more compositional ratios Rk with the same 'units' as atomic number (i.e. dimensionless). The model was turned to MEXA where it delivered reliable estimates for Ne and R4 and not the intermediate compositional ratios. This report studies the relationships between compositional ratios for tissues and tissue substitute materials. Correlations are identified leading to a new parameterization that is expressed as a nonlinear function of Ne, R4 and other coefficients. The properties of the transformed parameterizations for ? and the energy absorption coefficient ?en are considered for low atomic number materials at energies 15-100 keV, and for a broader range of materials at energies 5 keV to 20 MeV. The interpretation of the parameters Ne and R4 is explored in terms of basis materials. The general case of three basis materials cannot be solved for all contributions, but the special case of just two basis materials can be fully solved.

Midgley, S. M.

2011-05-01

141

First detection of correlated electron beams and plasma jets in radio and soft x-ray data  

NASA Astrophysics Data System (ADS)

From a common analysis of solar radio spectral and imaging data of a fast drift burst of type U(N) together with Yohko soft X-ray images it is shown that the radio emission is compatible with electron beams injected and reflected in extended loops. The electron beam production concides with the injection of hot matter, visible as a jetlike soft X-ray feature in the underlying loop system. the underlying loop system.

Aurass, H.; Klein, K.-L.; Martens, P. C. H.

1994-11-01

142

X-ray fluorescence analysis of spent reactor fuel solutions  

Microsoft Academic Search

The present work examines the possibility of laboratory analytic control by means of a crystal-free x-ray fluorescence analysis (XRFA) installation specifically designed for this purpose with a prior selection of fluorescent emissions by energy. Monitoring by fluorescent emissions from selenium positioned in the installation along with a metering cuvette allows the exclusion of errors associated with the instability of the

V. V. Berdikov; B. S. Iokhin

1987-01-01

143

Advanced Method for Fourier Analysis of X Ray Diffraction Profiles.  

National Technical Information Service (NTIS)

The use of two arcs of Pearson type VII distribution makes possible an accurate fitting of X-rays experimental line profile even in the asymmetrical case. This representation can be used, for the Fourier analysis of Bragg reflections, after having done, w...

S. Zirilli

1983-01-01

144

PROS: Multi-mission X-ray analysis software system  

NASA Astrophysics Data System (ADS)

PROS is a multi-mission x-ray analysis software system designed to run under IRAF. The PROS software includes spatial, spectral, timing, data I/O and conversion routines, plotting applications, and general algorithms for performing arithmetic operations with imaging data.

Conroy, M. A.; Deponte, J.; Moran, J. F.; Orszak, J. S.; Roberts, W. P.; Schmidt, D.

2013-06-01

145

Chemical bonding effects in X-ray spectral analysis  

Microsoft Academic Search

In this review we examine the use of chemical bonding effects apparent in x-ray spectra (chemical shift, change in shape and intensity of the lines) for qualitative and quantitative analysis of the chemical state of elements (charge state, valency, coordination number, chemical bond type, etc.), and also for direct identification of chemical compounds. In this connection, we examine methods of

L. N. Mazalov; B. A. Treiger

1983-01-01

146

Full spatial characterization of a nanofocused x-ray free-electron laser beam by ptychographic imaging  

PubMed Central

The emergence of hard X-ray free electron lasers (XFELs) enables new insights into many fields of science. These new sources provide short, highly intense, and coherent X-ray pulses. In a variety of scientific applications these pulses need to be strongly focused. In this article, we demonstrate focusing of hard X-ray FEL pulses to 125?nm using refractive x-ray optics. For a quantitative analysis of most experiments, the wave field or at least the intensity distribution illuminating the sample is needed. We report on the full characterization of a nanofocused XFEL beam by ptychographic imaging, giving access to the complex wave field in the nanofocus. From these data, we obtain the full caustic of the beam, identify the aberrations of the optic, and determine the wave field for individual pulses. This information is for example crucial for high-resolution imaging, creating matter in extreme conditions, and nonlinear x-ray optics.

Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C.; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B.; Nilsson, Daniel; Uhlen, Fredrik; Vogt, Ulrich; Hertz, Hans M.; Schroer, Christian G.

2013-01-01

147

Full spatial characterization of a nanofocused x-ray free-electron laser beam by ptychographic imaging.  

PubMed

The emergence of hard X-ray free electron lasers (XFELs) enables new insights into many fields of science. These new sources provide short, highly intense, and coherent X-ray pulses. In a variety of scientific applications these pulses need to be strongly focused. In this article, we demonstrate focusing of hard X-ray FEL pulses to 125 nm using refractive x-ray optics. For a quantitative analysis of most experiments, the wave field or at least the intensity distribution illuminating the sample is needed. We report on the full characterization of a nanofocused XFEL beam by ptychographic imaging, giving access to the complex wave field in the nanofocus. From these data, we obtain the full caustic of the beam, identify the aberrations of the optic, and determine the wave field for individual pulses. This information is for example crucial for high-resolution imaging, creating matter in extreme conditions, and nonlinear x-ray optics. PMID:23567281

Schropp, Andreas; Hoppe, Robert; Meier, Vivienne; Patommel, Jens; Seiboth, Frank; Lee, Hae Ja; Nagler, Bob; Galtier, Eric C; Arnold, Brice; Zastrau, Ulf; Hastings, Jerome B; Nilsson, Daniel; Uhlén, Fredrik; Vogt, Ulrich; Hertz, Hans M; Schroer, Christian G

2013-01-01

148

X-ray Fluorescence Analysis of Rare-Earth Atoms in Materials by Use of Ultrashort Wavelength X-rays  

Microsoft Academic Search

A new technique of X-ray fluorescence analysis using ultrashort-wavelength X-rays was tested to obtain the K-series of spectra for rare-earth elements in two different kinds of materials, i.e. powder samples of rare-earth oxides and single crystals of rare-earth hexaborides. This technique utilizes a solid-state detector and multichannel pulse-height analyzer, and satisfies the requirements for quantitative identification in samples containing heavy

Yasuhiko Takahashi; Kazuki Yamamoto; Ken-ichi Ohshima; Ken Yukino; Fujio P. Okamura

1998-01-01

149

Development of a micro-X-ray fluorescence system based on polycapillary X-ray optics for non-destructive analysis of archaeological objects  

Microsoft Academic Search

A new micro-X-ray fluorescence (micro-XRF) system based on rotating anode X-ray generator and polycapillary X-ray optics has been set up in XOL Lab, BNU, China, in order to be used for analysis of archaeological objects. The polycapillary X-ray optics used here can focus the primary X-ray beam down to tens of micrometers in diameter that allows for non-destructive and local

Lin Cheng; Xunliang Ding; Zhiguo Liu; Qiuli Pan; Xuelian Chu

2007-01-01

150

X-ray fluorescence/Auger-electron coincidence spectroscopy of vacancy cascades in atomic argon  

SciTech Connect

Argon L{sub 2.3}-M{sub 2.3}M{sub 2.3} Auger-electron spectra were measured in coincidence with K{alpha} fluorescent x-rays in studies of Ar K-shell vacancy decays at several photon energies above the K-threshold and on the 1s-4p resonance in atomic argon. The complex spectra recorded by conventional electron spectroscopy are greatly simplified when recorded in coincidence with fluorescent x-rays, allowing a more detailed analysis of the vacancy cascade process. The resulting coincidence spectra are compared with Hartree-Fock calculations which include shake-up transitions in the resonant case. Small energy shifts of the coincidence electron spectra are attributed to post-collision interaction with 1s photoelectrons.

Arp, U. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Electron and Optical Physics Div.; LeBrun, T.; Southworth, S.H.; Jung, M. [Argonne National Lab., IL (United States). Physics Div.; MacDonald, M.A. [E.P.S.R.C. Daresbury Lab., Warrington (United Kingdom)

1996-12-01

151

Characterization of Nonmelted Particles and Molten Splats in Plasma-Sprayed Al2O3 Coatings by a Combination of Scanning Electron Microscopy, X-ray Diffraction Analysis, and Confocal Raman Analysis  

NASA Astrophysics Data System (ADS)

Plasma-sprayed ceramic coatings are deposited by flattened splats together with some nonmelted particles. In this study, both nonmelted particles and molten splats in plasma-sprayed alumina coatings were examined by a combination of scanning electron microscopy, x-ray diffraction analysis, and confocal Raman analysis to aim at the comprehensive understanding and quantitative evaluation of coating microstructure. Results showed that the nonmelted particles can be clearly identified from the polished cross section due to the raised pattern morphology (with convexes) resulting from the higher hardness of the nonmelted particles than molten splats. Raman analysis revealed that there was little ?-Al2O3 phase in the flattened splat region, which confirmed that ?-Al2O3 phase in the coating originated only from nonmelted particles. Moreover, it is proposed that attention should be paid to the weak bonding of the nonmelted particles to surrounding flattened splats during the preparation of samples for the quantitative characterization of coating microstructure.

Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

2013-03-01

152

Few-femtosecond time-resolved measurements of X-ray free-electron lasers.  

PubMed

X-ray free-electron lasers, with pulse durations ranging from a few to several hundred femtoseconds, are uniquely suited for studying atomic, molecular, chemical and biological systems. Characterizing the temporal profiles of these femtosecond X-ray pulses that vary from shot to shot is not only challenging but also important for data interpretation. Here we report the time-resolved measurements of X-ray free-electron lasers by using an X-band radiofrequency transverse deflector at the Linac Coherent Light Source. We demonstrate this method to be a simple, non-invasive technique with a large dynamic range for single-shot electron and X-ray temporal characterization. A resolution of less than 1 fs root mean square has been achieved for soft X-ray pulses. The lasing evolution along the undulator has been studied with the electron trapping being observed as the X-ray peak power approaches 100 GW. PMID:24781868

Behrens, C; Decker, F-J; Ding, Y; Dolgashev, V A; Frisch, J; Huang, Z; Krejcik, P; Loos, H; Lutman, A; Maxwell, T J; Turner, J; Wang, J; Wang, M-H; Welch, J; Wu, J

2014-01-01

153

Few-femtosecond time-resolved measurements of X-ray free-electron lasers  

NASA Astrophysics Data System (ADS)

X-ray free-electron lasers, with pulse durations ranging from a few to several hundred femtoseconds, are uniquely suited for studying atomic, molecular, chemical and biological systems. Characterizing the temporal profiles of these femtosecond X-ray pulses that vary from shot to shot is not only challenging but also important for data interpretation. Here we report the time-resolved measurements of X-ray free-electron lasers by using an X-band radiofrequency transverse deflector at the Linac Coherent Light Source. We demonstrate this method to be a simple, non-invasive technique with a large dynamic range for single-shot electron and X-ray temporal characterization. A resolution of less than 1?fs root mean square has been achieved for soft X-ray pulses. The lasing evolution along the undulator has been studied with the electron trapping being observed as the X-ray peak power approaches 100?GW.

Behrens, C.; Decker, F.-J.; Ding, Y.; Dolgashev, V. A.; Frisch, J.; Huang, Z.; Krejcik, P.; Loos, H.; Lutman, A.; Maxwell, T. J.; Turner, J.; Wang, J.; Wang, M.-H.; Welch, J.; Wu, J.

2014-04-01

154

Total reflection X-ray fluorescence spectrometers for multielement analysis: status of equipment  

Microsoft Academic Search

Multielement analysis by total reflection X-ray fluorescence spectrometry has evolved during two decades. At present commercial equipment is available for chemical analysis of all types of biological and mineral samples. The electronic industry has also benefited from scientific and technological developments in this field due to new instrumentation to determine contamination on the surface of silicon wafers (the equipment will

Rony E. Ayala Jiménez

2001-01-01

155

A controlled dispersion parallel wavelength x ray spectrometer for electron microscopy  

Microsoft Academic Search

A new technique is described for the detection of x rays in electron column instruments used in microanalysis. In electron column instruments, the point source of x rays is produced by the interaction of a focused electron beam with the sample. Neither of the conventional methods, wavelength dispersive (WDS) nor energy dispersive (EDS) based spectrometry, is optimized for low Z

C. E. Fiori; S. A. Wight; A. D. Romig Jr.

1991-01-01

156

Femtosecond synchronism of x-rays and visible/infrared light in an x-ray free-electron laser  

SciTech Connect

A way is proposed to obtain ultrashort pulses of intense infrared/visible light in few-femtosecond synchronism with x-rays from an x-ray free-electron laser (XFEL). It makes use of the recently proposed emittance-slicing technique [Emma et al., Phys. Rev. Lett. 92, 074801 (2004)] to both restrict the duration of self-amplified spontaneous emission (SASE) to a few femtoseconds and to lead to a coherence enhancement of near-infrared transition undulator radiation (CTUR). The x-rays and the near-infrared light originate within the XFEL undulator from the same slice of electrons within a bunch and are therefore perfectly synchronized with each other. An example of realizing the scheme at the Linac Coherent Light Source is presented. A few side issues are explored briefly, such as the magnitude of the velocity term versus the acceleration term in the Lienard-Wiechert fields and the possible use of the CTUR as a diagnostic tool for the SASE process itself.

Adams, B. W. [Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2007-12-15

157

Femtosecond synchronism of x-rays and visible/infrared light in an x-ray free-electron laser.  

PubMed

A way is proposed to obtain ultrashort pulses of intense infrared/visible light in few-femtosecond synchronism with x-rays from an x-ray free-electron laser (XFEL). It makes use of the recently proposed emittance-slicing technique [Emma et al., Phys. Rev. Lett. 92, 074801 (2004)] to both restrict the duration of self-amplified spontaneous emission (SASE) to a few femtoseconds and to lead to a coherence enhancement of near-infrared transition undulator radiation (CTUR). The x-rays and the near-infrared light originate within the XFEL undulator from the same slice of electrons within a bunch and are therefore perfectly synchronized with each other. An example of realizing the scheme at the Linac Coherent Light Source is presented. A few side issues are explored briefly, such as the magnitude of the velocity term versus the acceleration term in the Lienard-Wiechert fields and the possible use of the CTUR as a diagnostic tool for the SASE process itself. PMID:18163725

Adams, B W

2007-12-01

158

A transmission x-ray microscope based on secondary-electron imaging  

Microsoft Academic Search

A design for a transmission x-ray microscope with 20 nm transverse spatial resolution is presented. The microscope, which is based on the electron-optical imaging of the photoemitted electrons from an x-ray shadowgraph, consists of a transmission x-ray photocathode coupled to a photoelectron emission microscope (PEEM—also called a PEM for photoelectron microscope). Unlike the conventional PEEM, which produces a surface map

R. N. Watts; S. Liang; Z. H. Levine; T. B. Lucatorto; F. Polack; M. R. Scheinfein

1997-01-01

159

X-ray fluorescence and electron microscopy study of plankton samples from the Novosibirsk reservoir  

Microsoft Academic Search

Five samples of plankton from the Novosibirsk reservoir are collected and analyzed by X-ray fluorescence. In combination with\\u000a high sensitive atomic absorption spectroscopy (AAS), inductively coupled plasma mass spectrometry (ICP-MS), and instrumental\\u000a neutron activation analysis (INAA), quantitative data on the concentrations of 52 chemical elements in plankton are obtained.\\u000a Scanning electron microscopy is used to analyze the elemental composition of

G. A. Leonova; V. A. Bobrov; E. V. Lazareva

2010-01-01

160

The identification of burnt matches by scanning electron microscopy\\/energy dispersive X-ray spectrometry  

Microsoft Academic Search

This study is first placed on the characterization of various burnt matches by scanning electron microscopy\\/energy dispersive X-ray spectrometry (SEM\\/EDS). The morphological and elemental features were used to investigate fire residues and to increase the discriminating effect of burnt matches. To find if there was further discrimination method, the cluster analysis of 74 boxes of matches based on the semi-quantitative

Yueh-Hsiang Chen

161

X-ray fluorescence analysis major elements in silicate minerals  

Microsoft Academic Search

An automated wavelength-dispersive x-ray fluorescence spectrometer is operational for analysis of major elements in rocks and minerals. Procedures for trace-element analysis are being developed. Sample preparation methods and analytical techniques are similar to those commonly used elsewhere, but data reduction is conducted by the Fundamental Parameters program developed by Criss. Unlike empirically derived calibration curves, this data reduction method considers

Hagan

1982-01-01

162

Soft X-Ray Analysis of NGC 4151  

Microsoft Academic Search

We present analysis of archival data from multiple XMM-Newton observations of NGC 4151. Spectral data from the RGS instruments reveal several strong soft X-ray emission lines, chiefly from hydrogen-like and helium-like oxygen, nitrogen, neon and carbon. Radiative recombination continuua (RRC) from oxygen and carbon are also detected. Our analysis suggests that the emission data are consistent with photoionization. Finally, we

B. K. Armentrout

2005-01-01

163

Intravenous coronary angiography utilizing K-emission and bremsstrahlung X-rays produced by electron bombardment  

SciTech Connect

The screening of the general population for coronary artery disease would be practical if a method existed for visualizing the extent of occlusion after an intravenous injection of contrast agent. Measurements performed with synchrotron radiation at SSRL and NSLS have shown that such an intravenous angiography procedure would be possible with an intense source of monochromatic X-rays. Because of the high cost of an electron synchrotron, theoretical analysis and experiments using inanimate phantoms has been undertaken to demonstrate the feasibility of using the spectrum produced by two appropriately chosen anode materials when bombarded with electrons in the 100--500 keV energy range for angiography. By using the X-rays emitted at 120{degree} to the incident electron direction, about 20--30% of the X-ray intensity would be due to K-emission lines. Calculations using the TIGERP Monte Carlo Code, have shown that high quality angiograms of human coronary arteries should be possible with a contrast agent containing ytterbium, if an electron beam pulses of 16 kJ were used for each anode target. The experimental program supported in part by the DOE has consisted of these theoretical calculations and experiments at the Dynamitron Electron Accelerator Facility at BNL.

NONE

1992-12-31

164

Coherence Properties of Individual Femtosecond Pulses of an X-ray Free-Electron Laser  

SciTech Connect

Measurements of the spatial and temporal coherence of single, femtosecond x-ray pulses generated by the first hard x-ray free-electron laser, the Linac Coherent Light Source, are presented. Single-shot measurements were performed at 780 eV x-ray photon energy using apertures containing double pinholes in 'diffract-and-destroy' mode. We determined a coherence length of 17 {micro}m in the vertical direction, which is approximately the size of the focused Linac Coherent Light Source beam in the same direction. The analysis of the diffraction patterns produced by the pinholes with the largest separation yields an estimate of the temporal coherence time of 0.55 fs. We find that the total degree of transverse coherence is 56% and that the x-ray pulses are adequately described by two transverse coherent modes in each direction. This leads us to the conclusion that 78% of the total power is contained in the dominant mode.

Vartanyants, I.A.; /DESY /Moscow Phys. Eng. Inst.; Singer, A.; Mancuso, A.P.; Yefanov, O.M.; /DESY; Sakdinawat, A.; Liu, Y.; Bang, E.; /UC, Berkeley; Williams, G.J.; /SLAC; Cadenazzi, G.; Abbey, B.; /Melbourne U.; Sinn, H.; /European XFEL, Hamburg; Attwood, D.; /UC, Berkeley; Nugent, K.A.; /Melbourne U.; Weckert, E.; /DESY; Wang, T.; Zhu, D.; Wu, B.; Graves, C.; Scherz, A.; Turner, J.J.; Schlotter, W.F.; /SLAC /LERMA, Ivry /Zurich, ETH /LBL, Berkeley /ANL, APS /Argonne /SLAC /LLNL, Livermore /Latrobe U. /SLAC /SLAC /European XFEL, Hamburg /SLAC /Hamburg U.

2012-06-06

165

The amorphous Zn biomineralization at Naracauli stream, Sardinia: electron microscopy and X-ray absorption spectroscopy.  

PubMed

An amorphous Zn biomineralization ("white mud"), occurring at Naracauli stream, Sardinia, in association with cyanobacteria Leptolyngbya frigida and diatoms, was investigated by electron microscopy and X-ray absorption spectroscopy. Preliminary diffraction analysis shows that the precipitate sampled on Naracauli stream bed is mainly amorphous, with some peaks ascribable to quartz and phyllosilicates, plus few minor unattributed peaks. Scanning electron microscopy analysis shows that the white mud, precipitated in association with a seasonal biofilm, is made of sheaths rich in Zn, Si, and O, plus filaments likely made of organic matter. Transmission electron microscopy analysis shows that the sheaths are made of smaller units having a size in the range between 100 and 200 nm. X-ray absorption near-edge structure and extended X-ray absorption fine structure data collected at the Zn K-edge indicate that the biomineral has a local structure similar to hemimorphite, a zinc sorosilicate. The differences of this biomineral with respect to the hydrozincite biomineralization documented about 3 km upstream in the same Naracauli stream may be related to either variations in the physicochemical parameters and/or different metabolic behavior of the involved biota. PMID:23832800

Medas, D; Lattanzi, P; Podda, F; Meneghini, C; Trapananti, A; Sprocati, A; Casu, M A; Musu, E; De Giudici, G

2014-06-01

166

Depth analysis of subgap electronic states in amorphous oxide semiconductor, a-In-Ga-Zn-O, studied by hard x-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

In a previous work, we examined subgap states in highly doped amorphous In-Ga-Zn-O (a-IGZO) films by hard x-ray photoelectron spectroscopy (HX-PES) and found they had subgap electronic states above the valence band maximum (VBM) with the densities > 5 × 1020 cm-3 and just below the Fermi level with the densities > 5 × 1019 cm-3 [K. Nomura, T. Kamiya, H. Yanagi, E. Ikenaga, K. Yang, K. Kobayashi, M. Hirano, and H. Hosono, Appl. Phys. Lett. 92, 202117 (2008)] however, their electron densities (Ne > 3 × 1019 cm-3) are rather high and not compatible with rational properties required for active channel layers in thin-film transistors (TFTs). In this work, we report the effects of Ne and thermal annealing on the subgap states in order to provide the data useful for actual TFTs. It was found that the low-Ne a-IGZO films had extra subgap states above VBM similar to the previous report, but their densities were as small as ~2.0 × 1020 cm-3 for the highly resistive, wet-annealed a-IGZO films. Angle-dependent HX-PES revealed that the subgap states above VBM concentrate in the surface region. The O 1s peak indicated that the wet annealing suppressed the generation of subgap states by terminating these states with -OH bonds. The subgap states below EF were observed commonly in all the samples including ZnO, crystalline (c-) IGZO and a-IGZO. It is concluded that these states below EF are neither related to the disordered structures of a-IGZO nor to their TFT characteristics. It is considered that these states are related to the metastable states created by the high-energy photons in vacuum.

Nomura, Kenji; Kamiya, Toshio; Ikenaga, Eiji; Yanagi, Hiroshi; Kobayashi, Keisuke; Hosono, Hideo

2011-04-01

167

Thin-window electron probe X-ray microanalysis of individual atmospheric particles above the North Sea  

Microsoft Academic Search

A recently developed, automated, standardless, quantitative analytical method, based on electron probe X-ray microanalysis using thin-window energy-dispersive X-ray detector technology, has proven to be a valuable tool for single particle analysis with the determination of the concentrations of light and heavier elements. The combined knowledge of low-Z element concentrations and air mass backward trajectories could give us information on the

J. de Hoog; J. Osán; I. Szalóki; K. Eyckmans; A. Worobiec; C.-U. Ro; R. Van Grieken

2005-01-01

168

ANALYSIS OF THE MICROBIOLOGICAL PARTICULATES IN MUNICIPAL DRINKING-WATER BY SCANNING ELECTRON MICROSCOPY/X-RAY ENERGY SPECTROSCOPY (ANALYSE VON BIOLOGISCHEN PARTIKELN IM TRINKWASSER DURCH RASTERELEKTRONEN-MIKROSKOPIE UND ELEKTRONENSTRAHLMIKROANALYSE)  

EPA Science Inventory

Scanning electron microscopy and X-ray energy spectroscopy (SEM/XES) were used to survey the biological and nonbiological particles in two different municipal drinking-water systems. Microbiological particles could be differentiated from nonbiological by their qualitative element...

169

Macromolecular structures probed by combining single-shot free-electron laser diffraction with synchrotron coherent X-ray imaging  

NASA Astrophysics Data System (ADS)

Nanostructures formed from biological macromolecular complexes utilizing the self-assembly properties of smaller building blocks such as DNA and RNA hold promise for many applications, including sensing and drug delivery. New tools are required for their structural characterization. Intense, femtosecond X-ray pulses from X-ray free-electron lasers enable single-shot imaging allowing for instantaneous views of nanostructures at ambient temperatures. When combined judiciously with synchrotron X-rays of a complimentary nature, suitable for observing steady-state features, it is possible to perform ab initio structural investigation. Here we demonstrate a successful combination of femtosecond X-ray single-shot diffraction with an X-ray free-electron laser and coherent diffraction imaging with synchrotron X-rays to provide an insight into the nanostructure formation of a biological macromolecular complex: RNA interference microsponges. This newly introduced multimodal analysis with coherent X-rays can be applied to unveil nano-scale structural motifs from functional nanomaterials or biological nanocomplexes, without requiring a priori knowledge.

Gallagher-Jones, Marcus; Bessho, Yoshitaka; Kim, Sunam; Park, Jaehyun; Kim, Sangsoo; Nam, Daewoong; Kim, Chan; Kim, Yoonhee; Noh, Do Young; Miyashita, Osamu; Tama, Florence; Joti, Yasumasa; Kameshima, Takashi; Hatsui, Takaki; Tono, Kensuke; Kohmura, Yoshiki; Yabashi, Makina; Hasnain, S. Samar; Ishikawa, Tetsuya; Song, Changyong

2014-05-01

170

Macromolecular structures probed by combining single-shot free-electron laser diffraction with synchrotron coherent X-ray imaging.  

PubMed

Nanostructures formed from biological macromolecular complexes utilizing the self-assembly properties of smaller building blocks such as DNA and RNA hold promise for many applications, including sensing and drug delivery. New tools are required for their structural characterization. Intense, femtosecond X-ray pulses from X-ray free-electron lasers enable single-shot imaging allowing for instantaneous views of nanostructures at ambient temperatures. When combined judiciously with synchrotron X-rays of a complimentary nature, suitable for observing steady-state features, it is possible to perform ab initio structural investigation. Here we demonstrate a successful combination of femtosecond X-ray single-shot diffraction with an X-ray free-electron laser and coherent diffraction imaging with synchrotron X-rays to provide an insight into the nanostructure formation of a biological macromolecular complex: RNA interference microsponges. This newly introduced multimodal analysis with coherent X-rays can be applied to unveil nano-scale structural motifs from functional nanomaterials or biological nanocomplexes, without requiring a priori knowledge. PMID:24786694

Gallagher-Jones, Marcus; Bessho, Yoshitaka; Kim, Sunam; Park, Jaehyun; Kim, Sangsoo; Nam, Daewoong; Kim, Chan; Kim, Yoonhee; Noh, Do Young; Miyashita, Osamu; Tama, Florence; Joti, Yasumasa; Kameshima, Takashi; Hatsui, Takaki; Tono, Kensuke; Kohmura, Yoshiki; Yabashi, Makina; Hasnain, S Samar; Ishikawa, Tetsuya; Song, Changyong

2014-01-01

171

Analysis of the Central X-ray Source in DG Tau  

NASA Astrophysics Data System (ADS)

As a stellar X-ray source DG Tau shows two rather unusual features: A resolved X-ray jet [2] and an X-ray spectrum best described by two thermal components with different absorbing column densities, a so called “two-absorber X-ray (TAX)” morphology [1, 2]. In an effort to understand the properties of the central X-ray source in DG Tau a detailed position analysis was carried out.

Schneider, P. Christian; Schmitt, Jürgen H. M. M.

172

ELECTRON MICROSCOPE AND X-RAY DIFFRACTION STUDIES ON A HOMOLOGOUS SERIES OF SATURATED PHOSPHATIDYLCHOLINES  

PubMed Central

Three homologous saturated phosphatidylcholines were studied by electron microscopy after tricomplex fixation. The results are compared with those obtained by x-ray diffraction analysis of the same and some other homologous compounds, in the dry crystalline state and after tricomplex fixation. By electron microscopy alternating dark and light bands are observed which are likely to correspond to phosphatide double layers. X-Ray diffraction reveals the presence of lamellar structures of regular spacing. The layer spacings obtained by both methods are in good agreement. From the electron micrographs the width of the polar parts of the double layers can be derived directly. The width of the carboxylglycerylphosphorylcholine moiety of the layers is found by extrapolating the x-ray diffraction data to zero chain length of the fatty acids. When from this width the contribution of the carboxylglyceryl part of the molecules is subtracted, again we find good agreement with the electron microscope measurements. An attempt has been made to account for the different layer spacings measured in terms of orientation of the molecules within the double layers.

Elbers, P. F.; Ververgaert, P. H. J. T.

1965-01-01

173

Probing electronic structure and chemical bonding with x-ray spectroscopy  

Microsoft Academic Search

The availability of synchrotron sources has expanded significantly the use of x-ray photoelectron (PE) and photoabsorption (PA) spectroscopy to probe the molecular electronic structure and to test the various bonding models the understanding of which is central to all aspects of chemistry. All features observed in x-ray spectra result from electronic transitions within the molecule, which are in turn determined

Astrid Jurgensen

1999-01-01

174

Crystallization and preliminary X-ray analysis of human angiogenin.  

PubMed

Crystals of recombinant human angiogenin have been grown from solutions containing sodium potassium tartrate and polyethylene glycol as precipitants. They belong to the space group C222(1) (a = 83.36 A, b = 120.64 A, c = 37.72 A) and contain a single molecule in the asymmetric unit. The crystals diffract to at least 2.3 A resolution and are suitable for three-dimensional X-ray structural analysis. PMID:1474591

Acharya, K R; Subramanian, V; Shapiro, R; Riordan, J F; Vallee, B L

1992-12-20

175

Nuclear Resonance Energy Analysis of Inelastic X-Ray Scattering  

Microsoft Academic Search

Inelastic scattering of x rays by gaseous, liquid, and solid samples was measured using a nuclear transition as a reference for the energy analysis of the scattered radiation. The samples were irradiated by a beam of synchrotron radiation with a bandwidth of 6.4 meV. The scattered radiation was analyzed using a resonance detector with a bandpass of 0.5 mueV. These

A. I. Chumakov; A. Q. R. Baron; R. Rüffer; H. Grünsteudel; A. Meyer

1996-01-01

176

Substrate selection for optimum qualitative and quantitative single atmospheric particles analysis using nano-manipulation, sequential thin-window electron probe X-ray microanalysis and micro-Raman spectrometry  

NASA Astrophysics Data System (ADS)

Sequential electron probe X-ray microanalysis using thin-window energy dispersive X-ray detection (TW-EDX-EPMA) and micro-Raman spectrometry (MRS) on the same atmospheric particle using nano-manipulation, is demonstrated. The advantageous combination of these two techniques allows information on the morphology, size, elemental and molecular composition, as well as the molecular structure of the same individual particle with a diameter as small as 500 nm. The use of an ultra-thin atmospheric window and a cold stage in EPMA enables qualitative and quantitative analysis of low-Z elements like C, N, and O as well as higher-Z elements. The work illustrates substrate optimisation and subsequent application in the analysis of atmospheric particles. Particle relocation was achieved by manipulative transfer onto transmission electron microscope grids, in an environmental scanning electron microscope, using 100 nm glass tips. A moderate correlation between the elemental composition obtained by TW-EDX-EPMA and the molecular fingerprint obtained by MRS is illustrated and its useful application in the interpretation of indoor air quality is discussed.

Godoi, Ricardo Henrique Moreton; Potgieter-Vermaak, Sanja; De Hoog, Johan; Kaegi, Ralf; Van Grieken, Rene

2006-04-01

177

Low-voltage electron-probe microanalysis of Fe-Si compounds using soft X-rays.  

PubMed

Conventional electron-probe microanalysis has an X-ray analytical spatial resolution on the order of 1-4 ?m width/depth. Many of the naturally occurring Fe-Si compounds analyzed in this study are smaller than 1 ?m in size, requiring the use of lower accelerating potentials and nonstandard X-ray lines for analysis. Problems with the use of low-energy X-ray lines (soft X-rays) of iron for quantitative analyses are discussed and a review is given of the alternative X-ray lines that may be used for iron at or below 5 keV (i.e., accelerating voltage that allows analysis of areas of interest <1 ?m). Problems include increased sensitivity to surface effects for soft X-rays, peak shifts (induced by chemical bonding, differential self-absorption, and/or buildup of carbon contamination), uncertainties in the mass attenuation coefficient for X-ray lines near absorption edges, and issues with spectral resolution and count rates from the available Bragg diffractors. In addition to the results from the traditionally used Fe L? line, alternative approaches, utilizing Fe L?, and Fe Ll-? lines, are discussed. PMID:23985089

Gopon, Phillip; Fournelle, John; Sobol, Peter E; Llovet, Xavier

2013-12-01

178

Win X-ray: A New Monte Carlo Program that Computes X-ray Spectra Obtained with a Scanning Electron Microscope  

Microsoft Academic Search

A new Monte Carlo program, Win X-ray, is presented that predicts X-ray spectra measured with an energy dispersive spectrometer (EDS) attached to a scanning electron microscope (SEM) operating between 10 and 40 keV. All the underlying equations of the Monte Carlo simulation model are included. By simulating X-ray spectra, it is possible to establish the optimum conditions to perform a

Raynald Gauvin; Eric Lifshin; Hendrix Demers; Paula Horny; Helen Campbell

2006-01-01

179

An X-Ray Free-Electron Laser Oscillator for Record High Spectral Purity and Average Brightness (Progress and Prospects for X-ray Free Electron Lasers)  

SciTech Connect

With the success of the LCLS at SLAC, synchrotron radiation community is entering the era of x-ray free-electron lasers (FELs) with an enormous jump in brightness and coherence over that possible with third-generation x-ray sources. The LCLS is a single-pass, high-gain device producing quasi-coherent x-rays known as self-amplified spontaneous emission. Hard x-ray FELs are also feasible in an oscillator (XFELO) configuration, in which an x-ray pulse is trapped a low-loss optical cavity consisting of diamond crystals, permitting build-up in the intensity and coherence over several hundred passes. An XFELO produces ultrahigh spectral purity and brightness-average brightness several orders of magnitude higher than, and peak brightness comparable to, self-amplified spontaneous emission devices; opening up new scientific opportunities as well as drastically improving and complementing experimental techniques developed at third-generation x-ray facilities. We discuss unique R&D issues in accelerator and x-ray optics and encouraging progress to date.

Kim, Kwang-Je (ANL) [ANL

2009-06-24

180

S-band linac-based X-ray source with ?\\/2-mode electron linac  

Microsoft Academic Search

The activities with the compact X-ray source are attracting more attention, particularly for the applications of the source in medical fields. We propose the fabrication of a compact X-ray source using the SAMEER electron linear accelerator and the KEK laser undulator X-ray source (LUCX) technologies. The linac developed at SAMEER is a standing wave side-coupled S-band linac operating in the

Abhay Deshpande; Sakae Araki; Tanuja Dixit; Masafumi Fukuda; R Krishnan; Sanjay Pethe; Kazuyuki Sakaue; Nobuhiro Terunuma; Junji Urakawa; Masakazu Washio

2011-01-01

181

A new principle in plasma electron-temperature diagnostics using a semiconductor x-ray detector  

Microsoft Academic Search

Recently, the energy responses of widely utilized seraiconductor X-ray detectors employed in many plasma-confmement devices were found to show contradictory behavior against the predietion from the conventional X-ray-energy-response theory in textbooks employed over the last quarter of the century for the analyses of plasma electron tem-peratures Te. This problem gave serious confusion for plasma researchers, who were utilizing X-ray data

T. Cho; J. Kohagura; M. Hirata; Y. Sakamoto; T. Okamura; T. Numakura; R. Minami; T. Sasuga; H. Nishizawa; T. Tamano; K. Yatsu; S. Miyoshi

1999-01-01

182

Proton-Induced X-Ray Emission Analysis.  

NASA Astrophysics Data System (ADS)

The aim of this thesis is to establish a solid mathematical basis for the use of thick target Proton Induced X-ray Emission (PIXE) analysis to the determination of trace element concentrations in solid samples. With the advent of high resolution Si(Li) detectors there was a revival of interest in the use of characteristic X-rays induced by high energy particle beams. It was shown that it is possible to use these X-rays to measure very low concentrations of trace elements in samples. Early work concentrated on the development of the method as a means of analysing thin films such as are encountered in monitoring air pollution. Work at Lucas Heights had concentrated on the use of ion beams for the analysis of archaeological artefacts using the technique of Particle induced Gamma ray emission (PIGME). Because of the necessity to use analysis methods that did not require destruction of the sample, our work had involved the use of targets that were thick (in terms of the incident particle). When it was decided to introduce PIXE at our laboratory, the filed of thick target PIXE analysis was little explored. In comparison with thin samples, as had normally been studied, the mathematical foundation for analysis had not been well established. My thesis is concerned with the study of that foundation. After a PIXE spectrum has been measured, there are essentially three steps in its interpretation. The first is to analyse the spectrum to extract the areas of the peaks which constitute that spectrum. For thick samples that analysis is complicated further by the effect of self absorption within the sample. This changes the ratios of the characteristic peak areas and must be modelled in the analysis program. After peak areas have been estimated, they are utilised to determine the concentration of the element emitting those X-rays. This involves modelling the processes that result in the emission of X-rays and their attenuation in the sample and detector system. Finally, as PIXE is a multielemental technique, producing information on possibly 15 to 20 elements in a single measurement, multivariate statistical methods may be necessary for the interpretation of the database produced by a series of PIXE measurements.

Clayton, Eric John

183

Limitations of ZAF correction factors in the determination of calcium/phosphorus ratios: Important forensic science considerations relevant to the analysis of bone fragments using scanning electron microscopy and energy-dispersive x-ray microanalysis  

SciTech Connect

A series of calcium phosphate standards having calcium/phosphorus (Ca/P) molar ratios of 0.50, 1.00, 1.50, and 1.67, respectively, was prepared for bulk specimen analysis using scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDXA). The standards were mounted on carbon planchettes as either pure crystals or crystals embedded in epoxy resin. Ten different samples of each embedded and non-embedded standard were analyzed in a JEOL 100 CX electron microscope interfaced with a Kevex 8000 EDXA system using a lithium-drifted silicon detector and a multichannel analyzer. The Ca/P ratios were determined by calculating both net peak intensities without matrix corrections and atomic kappa-ratios using the MAGIC V computer program with ZAF correction factors for quantitative analysis. There was such extensive absorption of phosphorus X-rays in standards embedded in an epoxy matrix that the observed Ca/P ratios were statistically compatible with four different standards ranging in theoretical Ca/P ratios from 1.0 to 1.67. Although the non-embedded crystals showed a greater separation in the Ca/P ratios, both methods of preparation produced serious flaws in analysis. Direct application of the discovery of this caveat to the identification of suspected bone fragments for forensic science purposes is discussed.

Payne, C.M.; Cromey, D.W. (Univ. of Arizona, Tucson (USA))

1990-05-01

184

Fluctuation analysis of stellar x-ray binary systems.  

PubMed

We study time series of x-ray sources of 129 stellar binary systems present in the public data collected by the instrument All Sky Monitor on board of the satellite Rossi X-Ray Timing Explorer. The light time series was analyzed by applying detrended fluctuation analysis to estimate the long-range power-law correlation exponents alpha. The scaling exponent was calculated for all systems and its value indicated a signature of each kind of system, i.e., whether flare takes place (with alpha=1.22) or not (with alpha=0.64). As a consequence, our results may identify the stability of the systems from the scaling exponent alpha value, for instance, if alpha approximately 0.5 (white noise) the system is stable and unstable when alpha not equal to 0.5 (long-range power-law correlation). PMID:14682920

Moret, M A; Zebende, G F; Nogueira Júnior, E; Pereira, M G

2003-10-01

185

Design and analysis of multilayer x ray/XUV microscope  

NASA Technical Reports Server (NTRS)

The design and analysis of a large number of normal incidence multilayer x ray microscopes based on the spherical mirror Schwarzschild configuration is examined. Design equations for the spherical mirror Schwarzschild microscopes are summarized and used to evaluate mirror parameters for microscopes with magnifications ranging from 2 to 50x. Ray tracing and diffraction analyses are carried out for many microscope configurations to determine image resolution as a function of system parameters. The results are summarized in three publication included herein. A preliminary study of advanced reflecting microscope configurations, where aspherics are used in place of the spherical microscope mirror elements, has indicated that the aspherical elements will improve off-axis image resolution and increase the effective field of view.

Shealy, David L.

1990-01-01

186

Atomic inner-shell X-ray laser at 1.46 nanometres pumped by an X-ray free-electron laser.  

PubMed

Since the invention of the laser more than 50 years ago, scientists have striven to achieve amplification on atomic transitions of increasingly shorter wavelength. The introduction of X-ray free-electron lasers makes it possible to pump new atomic X-ray lasers with ultrashort pulse duration, extreme spectral brightness and full temporal coherence. Here we describe the implementation of an X-ray laser in the kiloelectronvolt energy regime, based on atomic population inversion and driven by rapid K-shell photo-ionization using pulses from an X-ray free-electron laser. We established a population inversion of the K? transition in singly ionized neon at 1.46 nanometres (corresponding to a photon energy of 849 electronvolts) in an elongated plasma column created by irradiation of a gas medium. We observed strong amplified spontaneous emission from the end of the excited plasma. This resulted in femtosecond-duration, high-intensity X-ray pulses of much shorter wavelength and greater brilliance than achieved with previous atomic X-ray lasers. Moreover, this scheme provides greatly increased wavelength stability, monochromaticity and improved temporal coherence by comparison with present-day X-ray free-electron lasers. The atomic X-ray lasers realized here may be useful for high-resolution spectroscopy and nonlinear X-ray studies. PMID:22281598

Rohringer, Nina; Ryan, Duncan; London, Richard A; Purvis, Michael; Albert, Felicie; Dunn, James; Bozek, John D; Bostedt, Christoph; Graf, Alexander; Hill, Randal; Hau-Riege, Stefan P; Rocca, Jorge J

2012-01-26

187

Validation of x-ray line ratios for electron temperature determination in tokamak plasmas  

NASA Astrophysics Data System (ADS)

X-ray imaging crystal spectroscopy (XICS) has been implemented on magnetic confinement fusion devices as a novel means of measuring local plasma temperature, impurity density, and flow profiles. At Alcator C-Mod, XICS allows for spatially-resolved, high spectral resolution measurements between 0.3 and 0.4 nm, enabling detailed analysis of He-like argon x-ray emission. Electron temperatures in the range of 0.5?keV ?Te ?3.0?keV are determined from He-like argon emissivity ratios of the n = 3 dielectronic satellites to the w-line and its surrounding n ? 3 satellites, specifically the wavelength range of 3.9440?Å ? ? ? 3.9607?Å. These data are validated against measurements of Te from existing electron cyclotron emission and Thomson scattering diagnostics. Line ratio data are analysed via a tomographic inversion procedure, overcoming the traditional issue of spectra being averaged over the plasma cross-section. The implications of utilizing x-ray line ratios as a valid local temperature diagnostic are not limited to Alcator C-Mod; properties of plasma in future experiments as well as in astrophysical settings can also be investigated. The results of this experiment confirm that x-ray line ratios can be used as an accurate electron temperature diagnostic. The electron temperature can be determined from the relation to the line ratio, x, as Te[keV] = 0.1552x?0.7781 with 0.0223 < x < 0.2449.

Rosen, A. S.; Reinke, M. L.; Rice, J. E.; Hubbard, A. E.; Hughes, J. W.

2014-05-01

188

Non-destructive Analysis of Buried Interfaces and Surface Layers: X-Ray Emission Spectroscopic Study  

NASA Astrophysics Data System (ADS)

Soft X-ray emission spectroscopy (SXES) and extended X-ray emission fine structure (EXEFS) studies have been carried out on a heat-treated thin-film(Ni)/substrate(Si, SiC) contact system using a conventional X-ray micro-analysis (XMA) apparatus. We have successfully deduced information either the chemical bonding or atomic configuration by the former and the latter, respectively. Also, we have succeeded in analyzing an interface buried rather deep below an overlayer, e.g., more than a hundred nm. This is due to the fact that both an X-ray production depth of an energetic electron is much larger than the mean free path of an energetic electron and the mean free path of an X-ray photon in a solid is large. Namely, in the surface, or interface layer, Ni2Si and NiSi2 formation have been clarified for heat-treated Ni/SiC and Ni/Si systems, respectively.

Iwami, Motohiro; Hirai, Masaaki; Kusaka, Masahiko; Morii, Takashi

2003-07-01

189

Temporal cross-correlation of x-ray free electron and optical lasers using soft x-ray pulse induced transient reflectivity.  

PubMed

The recent development of x-ray free electron lasers providing coherent, femtosecond-long pulses of high brilliance and variable energy opens new areas of scientific research in a variety of disciplines such as physics, chemistry, and biology. Pump-probe experimental techniques which observe the temporal evolution of systems after optical or x-ray pulse excitation are one of the main experimental schemes currently in use for ultrafast studies. The key challenge in these experiments is to reliably achieve temporal and spatial overlap of the x-ray and optical pulses. Here we present measurements of the x-ray pulse induced transient change of optical reflectivity from a variety of materials covering the soft x-ray photon energy range from 500eV to 2000eV and outline the use of this technique to establish and characterize temporal synchronization of the optical-laser and FEL x-ray pulses. PMID:22565760

Krupin, O; Trigo, M; Schlotter, W F; Beye, M; Sorgenfrei, F; Turner, J J; Reis, D A; Gerken, N; Lee, S; Lee, W S; Hays, G; Acremann, Y; Abbey, B; Coffee, R; Messerschmidt, M; Hau-Riege, S P; Lapertot, G; Lüning, J; Heimann, P; Soufli, R; Fernández-Perea, M; Rowen, M; Holmes, M; Molodtsov, S L; Föhlisch, A; Wurth, W

2012-05-01

190

Soft x-ray emission from millimeter-wave electron cyclotron resonance discharge.  

PubMed

This work is devoted to the experimental investigation of incoherent soft x-ray radiation from an electron cyclotron resonance discharge with pumping by a millimeter-wave beam from a gyrotron. The basic contribution to the x-ray spectrum was shown to be produced by a plasma emission in the wavelength region 4.5-12 nm. The power of the x-ray emission from the ECR discharge was about 35 kW, and the efficiency of conversion of the gyrotron radiation into an x-ray emission exceeded 25%. PMID:21307525

Golubev, S V; Platonov, Y Y; Razin, S V; Zorin, V G

1996-01-01

191

Three-Dimensional X-ray Observation of Atmospheric Biological Samples by Linear-Array Scanning-Electron Generation X-ray Microscope System  

PubMed Central

Recently, we developed a soft X-ray microscope called the scanning-electron generation X-ray microscope (SGXM), which consists of a simple X-ray detection system that detects X-rays emitted from the interaction between a scanning electron beam (EB) and the thin film of the sample mount. We present herein a three-dimensional (3D) X-ray detection system that is based on the SGXM technology and designed for studying atmospheric biological samples. This 3D X-ray detection system contains a linear X-ray photodiode (PD) array. The specimens are placed under a CuZn-coated Si3N4 thin film, which is attached to an atmospheric sample holder. Multiple tilt X-ray images of the samples are detected simultaneously by the linear array of X-ray PDs, and the 3D structure is calculated by a new 3D reconstruction method that uses a simulated-annealing algorithm. The resulting 3D models clearly reveal the inner structure of the bacterium. In addition, the proposed method can easily be used for diverse samples in a broad range of scientific fields.

Ogura, Toshihiko

2011-01-01

192

Calculation of x-ray spectra emerging from an x-ray tube. Part I. electron penetration characteristics in x-ray targets.  

PubMed

The penetration characteristics of electron beams into x-ray targets are investigated for incident electron kinetic energies in the range 50-150 keV. The frequency densities of electrons penetrating to a depth x in a target, with a fraction of initial kinetic energy, u, are calculated using Monte Carlo methods for beam energies of 50, 80, 100, 120 and 150 keV in a tungsten target. The frequency densities for 100 keV electrons in Al, Mo and Re targets are also calculated. A mixture of simple modeling with equations and interpolation from data is used to generalize the calculations in tungsten. Where possible, parameters derived from the Monte Carlo data are compared to experimental measurements. Previous electron transport approximations in the semiempirical models of other authors are discussed and related to this work. In particular, the crudity of the use of the Thomson-Whiddington law to describe electron penetration and energy loss is highlighted. The results presented here may be used towards calculating the target self-attenuation correction for bremsstrahlung photons emitted within a tungsten target. PMID:17654919

Poludniowski, Gavin G; Evans, Philip M

2007-06-01

193

Substrate selection for optimum qualitative and quantitative single atmospheric particles analysis using nano-manipulation, sequential thin-window electron probe X-ray microanalysis and micro-Raman spectrometry  

Microsoft Academic Search

Sequential electron probe X-ray microanalysis using thin-window energy dispersive X-ray detection (TW-EDX-EPMA) and micro-Raman spectrometry (MRS) on the same atmospheric particle using nano-manipulation, is demonstrated. The advantageous combination of these two techniques allows information on the morphology, size, elemental and molecular composition, as well as the molecular structure of the same individual particle with a diameter as small as 500

Ricardo Henrique Moreton Godoi; Sanja Potgieter-Vermaak; Johan de Hoog; Ralf Kaegi; Rene van Grieken

2006-01-01

194

Substrate selection for optimum qualitative and quantitative single atmospheric particles analysis using nano-manipulation, sequential thin-window electron probe X-ray microanalysis and micro-Raman spectrometry  

Microsoft Academic Search

Sequential electron probe X-ray microanalysis using thin-window energy dispersive X-ray detection (TW-EDX-EPMA) and micro-Raman spectrometry (MRS) on the same atmospheric particle using nano-manipulation, is demonstrated. The advantageous combination of these two techniques allows information on the morphology, size, elemental and molecular composition, as well as the molecular structure of the same individual particle with a diameter as small as 500 nm.

Ricardo Henrique Moreton Godoi; Sanja Potgieter-Vermaak; Johan De Hoog; Ralf Kaegi; Rene Van Grieken

2006-01-01

195

Monte Carlo Electron Trajectory Simulation of X-ray Emission from Films Supported on Substrates.  

National Technical Information Service (NTIS)

The development of a Monte Carlo electron trajectory simulation for application to scanning electron microscopy and x-ray microanalysis involves several possible choices of elastic scattering and energy loss models, as well as for inner shell ionization. ...

D. E. Newbury E. B. Steel R. L. Myklebust

1990-01-01

196

Electron-beam-based sources of ultrashort x-ray pulses  

SciTech Connect

A review of various methods for generation of ultrashort X-ray pulses using relativistic electron beam from conventional accelerators is presented. Both spontaneous and coherent emission of electrons are considered.

Zholents, A. (Accelerator Systems Division (APS))

2010-01-01

197

Flash X-Ray (FXR) Accelerator Optimization Electronic Time-Resolved Measurement of X-Ray Source Size  

Microsoft Academic Search

Lawrence Livermore National Laboratory (LLNL) is currently investigating various approaches to minimize the x-ray source size on the Flash X-Ray (FXR) linear induction accelerator in order to improve x-ray flux and increase resolution for hydrodynamic radiography experiments. In order to effectively gauge improvements to final x-ray source size, a fast, robust, and accurate system for measuring the spot size is

J Jacob; M Ong; P Wargo

2005-01-01

198

An optimal target-filter system for electron beam generated x-ray spectra  

SciTech Connect

An electron beam generated x-ray spectrum consists of characteristic x rays of the target and continuous bremsstrahlung. The percentage of characteristic x rays over the entire energy spectrum depends on the beam energy and the filter thickness. To determine the optimal electron beam energy and filter thickness, one can either conduct many experimental measurements, or perform a series of Monte Carlo simulations. Monte Carlo simulations are shown to be an efficient tool for determining the optimal target-filter system for electron beam generated x-ray spectra. Three of the most commonly used low-energy x-ray metal targets (Cu, Zn and Mo) are chosen for this study to illustrate the power of Monte Carlo simulations.

Hsu, Hsiao-Hua; Vasilik, D.G. [Los Alamos National Lab., NM (United States); Chen, J. [GSF, Institut fur Strahlenbiologie, Neuherberg (Germany)

1994-04-01

199

Identification of thorium dioxide in human liver cells by electron microscopic x-ray microanalysis  

Microsoft Academic Search

Thirty-two years after injection of thorium dioxide (Thorotrast) for diagnostic x-ray studies in a female patient deposits were found by light microscopy in the liver macrophages (Kupffer cells). They were shown by electron microscopy to be located inside secondary lysosomes, and by autoradiography and x-ray microanalysis they were identified as thorium.

A Odegaard; E M Ophus; A M Larsen

1978-01-01

200

The effect of anisotropy of accelerated electrons on hard X-ray spectra of solar flares  

NASA Astrophysics Data System (ADS)

The calculations of X-ray spectra of solar flares were made analytically taking account of electron multiple scattering and radiation reflection from the photosphere. They showed a strong dependence of the radiation spectrum shape on the heliocentric angle of the flares. The analysis of the mean radiation spectra hardness versus the observation angle of the flares detected by SIGN-2M3 instruments in the range of 50 - 300 keV revealed a systematical softening of the spectra towards the centre of the solar disk. The comparison of the calculated radiation spectra with the observed ones points to the generation of electrons with anisotropic angular distribution in solar flares.

Bogovalov, S. V.; Kel'Ner, S. R.; Kotov, Iu. D.; Zenchenko, V. M.; Vedrenne, G.

201

Specimen preparation for x-ray fluorescence analysis of solutions  

SciTech Connect

Specimens for x-ray fluorescence analysis (XRFA) were prepared by adding dry gelatine (10%) to the analysis solution, homogenizing the mixture and cooling for 20 minutes. Thus, a compact resilient mass could be formed with the required shape and size; the roughness of the surface was determined by the roughness of the surface on which the specimen was formed, much the same as highly polished. Various calibration methods can be applied in the XRFA of a variety of materials if such specimens are used. 12 refs., 1 fig., 2 tabs.

Eksperiandova, L.P.; Spolnik, Z.M.; Blank, A.B.; Aliseychik, B.B. [Inst. for Single Crystals, Kharkov (Ukraine)

1995-12-31

202

X-Ray Microanalysis and Electron Energy Loss Spectrometry in the Analytical Electron Microscope: Review and Future Directions  

NASA Technical Reports Server (NTRS)

This paper reviews and discusses future directions in analytical electron microscopy for microchemical analysis using X-ray and Electron Energy Loss Spectroscopy (EELS). The technique of X-ray microanalysis, using the ratio method and k(sub AB) factors, is outlined. The X-ray absorption correction is the major barrier to the objective of obtaining I% accuracy and precision in analysis. Spatial resolution and Minimum Detectability Limits (MDL) are considered with present limitations of spatial resolution in the 2 to 3 microns range and of MDL in the 0.1 to 0.2 wt. % range when a Field Emission Gun (FEG) system is used. Future directions of X-ray analysis include improvement in X-ray spatial resolution to the I to 2 microns range and MDL as low as 0.01 wt. %. With these improvements the detection of single atoms in the analysis volume will be possible. Other future improvements include the use of clean room techniques for thin specimen preparation, quantification available at the I% accuracy and precision level with light element analysis quantification available at better than the 10% accuracy and precision level, the incorporation of a compact wavelength dispersive spectrometer to improve X-ray spectral resolution, light element analysis and MDL, and instrument improvements including source stability, on-line probe current measurements, stage stability, and computerized stage control. The paper reviews the EELS technique, recognizing that it has been slow to develop and still remains firmly in research laboratories rather than in applications laboratories. Consideration of microanalysis with core-loss edges is given along with a discussion of the limitations such as specimen thickness. Spatial resolution and MDL are considered, recognizing that single atom detection is already possible. Plasmon loss analysis is discussed as well as fine structure analysis. New techniques for energy-loss imaging are also summarized. Future directions in the EELS technique will be the development of new spectrometers and improvements in thin specimen preparation. The microanalysis technique needs to be simplified and software developed so that the EELS technique approaches the relative simplicity of the X-ray technique. Finally, one can expect major improvements in EELS imaging as data storage and processing improvements occur.

Goldstein, J. I.; Williams, D. B.

1992-01-01

203

Phase contrast: the frontier of x-ray and electron imaging  

NASA Astrophysics Data System (ADS)

Phase contrast has been a fundamental component of microscopy since the early 1940s. In broad terms, it refers to the formation of images using not the combination of wave intensities but their amplitudes with the corresponding phase factors. The impact on visible microscopy of biological specimens has been major. This contrast mechanism is now playing an increasingly important role in other kinds of microscopy, notably those based on electrons or x-rays. It notably solves the background problem of weak absorption contrast. New breakthroughs and new techniques are continuously produced, unfortunately unknown to most of the scientists that could exploit them. The present special cluster issue of reviews was inspired by this situation. The case of x-rays is very interesting. Phase contrast requires a high degree of longitudinal and lateral coherence. But conventional x-ray sources are not coherent. The progress of synchrotron sources yielded high coherence as a key byproduct—and started a rapid expansion of phase contrast radiology. No review—or cluster of reviews—can possibly cover all the facets of the recent progress. Without trying to be absolutely comprehensive, the present special cluster issue touches a variety of issues, giving a very broad picture. Liu et al review in general terms the different phase-based hard-x-ray techniques, with an interesting variety of examples. Then, Suortti et al and Wang et al present more specialized overviews of crystal and grating based x-ray imaging techniques, very powerful in the analysis of biological specimens. Mokso et al discuss the many facets of tomography using phase effects, expanding the picture of tomographic reconstruction of the three previous reviews. Wu et al treat the rapid progress in hard-x-ray focusing and its impact on radiology and tomography for materials science and biomedical research. The next two reviews deal with special and very interesting classes of applications. Specifically, Lee et al discuss the use of the new radiology techniques in the study of liquids, and Coan et al present the progress in phase-contrast radiology analysis of real patients. Although x-ray imaging is the main focus of the special cluster issue, the picture would not be complete without a view on the parallel and very exciting developments in electron microscopy. The last review, by Wu et al , is dedicated indeed to this broader picture, presenting recent progress in Zernike-related electron phase contrast. We trust that the special cluster issue will not only update readers on the evolution of a very important class of experimental techniques, but also prepare them for the forthcoming developments. We are indeed at the threshold of another revolution. The recently inaugurated first x-ray free electron lasers bring, together with many other record performances, full lateral coherence and excellent longitudinal coherence. The first imaging experiments show in practice their impact, and indicate that this field, far from saturating its progress, is ready for new major breakthroughs.

Hwu, Y.; Margaritondo, G.

2013-12-01

204

Hot electron diagnostics using X-ray imaging on GAMMA10  

NASA Astrophysics Data System (ADS)

In a tandem mirror the electrostatic potential at the end mirror cell plays a key role in plugging intrinsic ion loss in a single mirror. In the GAMMA10 axisymmetrized tandem mirror with thermal barrier, hot electrons are produced in both end mirrors through electron cyclotron resonance heating (ECRH). The electrostatic potential formed at the ECR is for end plugging, and the potential at the second harmonic resonance is for the thermal barrier, allowing selective heating of plug electrons. One critical issue of GAMMA10 is to confirm experimentally that hot electrons are actually produced in a radial distribution and peaked or abundantly filled on the magnetic axis. Bremsstrahlung X-rays are directly related to hot electrons, therefore the distribution of hot electrons can be deduced from X-ray imaging diagnostics. The temperature of hot electrons is measured to be about 50 keV. Taking into account the energy range of X-rays emitted from hot electrons, microchannel plates (MCP's) are used as position sensitive X-ray detectors. Two types of X-ray imaging systems are used. One is an X-ray pinhole camera and the other is a multichord detection system. The former is suitable for two-dimensional imaging with medium time resolution, the later is for fast time response imaging. From X-ray intensity distribution measurements, it has been confirmed that hot electrons distribute in a shape where the peak exists on the magnetic axis. The ratio of X-ray intensities through different filters is also applied to determine the spatial profile of hot electron temperature. The detection efficiency of MCP's has been measured by using radiations from a storage ring and an X-ray tube.

Yamaguchi, N.; Cho, T.; Kondoh, T.; Hirata, M.; Miyoshi, S.

1988-03-01

205

Continuous X-ray induced Auger microprobe analysis and microscopy: First results  

NASA Astrophysics Data System (ADS)

X-ray induced Auger electron spectroscopy can be applied to the chemical analysis of thin samples with a spatial resolution in the 10 ?m range. The first experimental results obtained with various anode materials and various samples are reported. The signal intensities (in the range of 10 3 counts/s) are similar to those obtained by using a conventional electron spectrometer with a resolution in the millimeter range. Theoretical considerations together with the results obtained make it possible to evaluate the sensitivity of this technique and suggest how the spatial resolution can be improved further (20 ?m at present, 2-3 ?m in the near future). The radiation damage and sample thickness constraints of this new technique and of conventional Auger electron spectros- copy are compared. Application of X-ray induced Auger analysis to biological objects is suggested and the effect of the present results on scanning X-ray radiography and characteristic X-ray absorption microanalysis is also pointed out.

Nassiopoulos, A. G.; Gramari, D.; Cazaux, J.

1983-06-01

206

Laser-pumped coherent x-ray free-electron laser  

NASA Astrophysics Data System (ADS)

In a laser-pumped x-ray free-electron laser (FEL) an intense laser field replaces the magnetic wiggler field of a conventional FEL. Depending on the intensity and quality of both the electron beam and pump laser, the Thomson backscattered radiation can be coherently amplified. In a conventional FEL the generation of x rays requires electron beam energies in the multi-GeV range. In a laser-pumped x-ray FEL, electron beam energies in the multi-MeV range would be sufficient. To generate coherent x rays with this mechanism a number of physics and technology issues must be addressed. Foremost among these are the stringent requirements placed on the electron beam quality and brightness as well as on the pump laser. The seed radiation for the laser-pumped FEL is the laser-induced spontaneous radiation. The evolution of incoherent radiation into coherent radiation as well as the power gain lengths associated with the coherent x rays are analyzed and discussed. There is excellent agreement between our analytical results and GENESIS simulations for the radiated power, gain length, conversion efficiency, linewidth, and saturation length. These issues, as well as others, necessary to achieve coherent amplified x rays in a laser-pumped FEL are discussed. While a coherent x-ray source would have a number of attractive features, the requirements placed on both the electron beam and pump laser are extremely challenging.

Sprangle, P.; Hafizi, B.; Peñano, J. R.

2009-05-01

207

Proposal for a pulse-compression scheme in x-ray free-electron lasers to generate a multiterawatt, attosecond x-ray pulse.  

PubMed

A novel scheme to compress the radiation pulse in x-ray free electron lasers is proposed not only to shorten the pulse length but also to enhance the peak power of the radiation, by inducing a periodic current enhancement with an optical laser and applying a temporal shift between the optical and electron beams. Calculations show that a 10-keV x-ray pulse with a peak power of 5 TW and a pulse length of 50 asec can be generated by applying this scheme to an existing x-ray free electron laser facility. PMID:23473154

Tanaka, Takashi

2013-02-22

208

Capillary Optics Based X-Ray Micro-Imaging Elemental Analysis  

Microsoft Academic Search

A rapidly developed during the last few years micro-X-ray fluorescence spectrometry (muXRF) is a promising multi-elemental technique for non-destructive analysis. Typically it is rather hard to perform laboratory muXRF analysis because of the difficulty of producing an original small-size X-ray beam as well as its focusing. Recently developed for X-ray beam focusing polycapillary optics offers laboratory X-ray micro probes. The

D. Hampai; S. B. Dabagov; G. Cappuccio; A. Longoni; T. Frizzi; G. Cibin

2010-01-01

209

Identification of Selected Silicate Minerals and their Asbestiform Varieties by Electron Optical and X-Ray Techniques.  

National Technical Information Service (NTIS)

Illustrations of electron micrographs showing morphology, electron diffraction patterns, energy dispersive X-ray spectra, and X-ray diffraction patterns of selected silicates and their asbestiform varieties are presented as an aid in their identification....

J. L. Miller

1978-01-01

210

Heavy ion induced Auger electron, x-ray, and optical emission from a solid state surface  

SciTech Connect

The experiments examine the relaxation phenomena of Auger electron, x-ray, and optical emission during the medium-keV heavy-ion bombardment of a solid state surface. Auger electron energy spectra, x-ray, and optical spectra induced by Ar/sup +/ and Ne/sup +/ ions with energies within the 100-350 keV range were recorded at the same time. The spectral structure observed for each of the emissions has provided information on electronic transitions, selected thin-foil sputtering yields and particle-induced x-ray emission cross sections.

Trbojevic, D.

1984-01-01

211

Miniature X-Ray Tubes  

NASA Technical Reports Server (NTRS)

Miniature x-ray tubes proposed for use in portable instruments used to analyze minerals. Electrons from field emitter (instead of thermionic emitter) accelerated to target to generate x-rays. Fabricated from silicon wafers, micromachined field emitters (MFEs) not subject to breakage or restrictions on lifetimes, and tolerate vacuums that filaments cannot. Miniature x-ray tubes very robust, immune to shock and vibration, and permanently sealed with getter for continued pumping. Combined with solid-state x-ray detectors for analysis of x-ray fluorescence.

Bearman, Gregory H.

1995-01-01

212

Aging of fluoropolymers irradiated by X-Rays, low energy electrons and energetic heavy ions  

Microsoft Academic Search

Polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) samples have been irradiated with X-rays, electrons and energetic heavy ions. Changes of electronic structure and chemical bonding have been studied by X-ray photoelectron spectroscopy (XPS).Under electron bombardment, a surface modification of PTFE is first observed (C =. C bond formation). Then bulk reticulation and new bond creation appearsThe variation of the C15 line

J. P. Duraud; A. Le Moël; C. Le Gressus

1986-01-01

213

Ultrafast electronic dynamics in polyatomic molecules studied using femtosecond vacuum ultraviolet and x-ray pulses  

NASA Astrophysics Data System (ADS)

Time-resolved velocity map photoelectron imaging is performed using sub-20 fs deep ultraviolet and vacuum ultraviolet pulses to study electronic dynamics of isolated polyatomic molecules. The non-adiabatic dynamics of pyrazine, furan and carbon disulfide (CS2) are described as examples. Also described is sub-picosecond time-resolved x-ray direct absorption spectroscopy using a hard x-ray free electron laser (SACLA) and a synchronous near ultraviolet laser to study ultrafast electronic dynamics in solutions.

Suzuki, Toshinori

2014-06-01

214

Near-monochromatic X-ray beams produced by the free electron laser and Compton backscatter  

Microsoft Academic Search

The intense photon output of a free electron laser may be made to collide with its own high energy electron beam to create nearly monochromatic x-rays using Compton backscatter techniques. These x-rays can be used for imaging and non-imaging diagnostic and therapeutic experiments. The initial configuration of the Vanderbilt Medical Free Electron Laser (Sierra Laser Systems, Sunnyvale, CA) produces intense

FRANK E. CARROLL; JAMES W. WATERS; RON R. PRICE; CHARLES A. BRAU; CARLTON F. ROOS; NORMAN H. TOLK; DAVID R. PICKENS; W. HOYT STEPHENS

1990-01-01

215

Global-scale electron precipitation features seen in UV and X rays during substorms  

Microsoft Academic Search

The Polar Ionospheric X-ray Imaging Experiment (PIXIE) and the ultraviolet imager (UVI) onboard the Polar satellite have provided the first simultaneous global-scale views of the patterns of electron precipitation through imaging of the atmospheric X-ray bremsstrahlung and the auroral ultraviolet (UV) emissions. While the UV images respond to the total electron energy flux, which is usually dominated by electron energies

N. Østgaard; J. Stadsnes; J. Bjordal; R. R. Vondrak; S. A. Cummer; D. L. Chenette; G. K. Parks; M. J. Brittnacher; D. L. McKenzie

1999-01-01

216

77 FR 12226 - Sadex Corp.; Filing of Food Additive Petition (Animal Use); Electron Beam and X-Ray Sources for...  

Federal Register 2010, 2011, 2012, 2013

...Animal Use); Electron Beam and X-Ray Sources for Irradiation of Poultry...for the safe use of electron beam and x-ray sources for irradiation of poultry...for the safe use of electron beam and x- ray sources for irradiation of...

2012-02-29

217

Investigation of surface structure with X-ray absorption and electron emission spectroscopies  

NASA Astrophysics Data System (ADS)

The use of electron spectromicroscopy for the study of the chemical composition and electronic properties of surfaces, overlayers, and interfaces has become widely accepted. Improvements to the optics of instruments such as the X-ray photo electron emission microscope have pushed spectroscopic microscopies into the realm of very high spatial resolution, at and below 1 micrometer [1]. Coupled with the high spectral resolution available from third generation synchrotron sources, this spatial resolution allows the measurement of micro-X-ray absorption near-edge spectra in addition to the more typical electron emission spectra and diffraction patterns. Complementary to the experimental developments is the development of improved theoretical methods for computational modeling of X-ray absorption and emission spectroscopies. In the field of tribochemistry, zinc dialkyl dithiophosphate (ZDDP) has long been a topic of much study. ZDDP is widely used as an anti-wear additive in engine oils and there is interest in determining the decomposition products of ZDDP that provide this protection against friction. An analysis of X-ray absorption near-edge spectra of thermal films from ZDDP samples is presented, including a comparison of the Zinc L-edge spectra with model calculations [2]. It was found essential to carry out self-consistent calculations of the electronic structure for the modeling. For the techniques of electron diffraction, a new method for a full multiple-scattering calculation of diffraction patterns from crystals with two-dimensional periodicity parallel to the surface is presented [3]. The calculation makes use of Helmholtz's reciprocity principle to compute the path-reversed process of the back propagation of a photoelectron from the position of a distant detector to that of the emitting atom. Early application is demonstrated with simulations of 64 eV M2,3VV and 914 eV L 2,3VV Auger electron diffraction from a Cu(001) surface. The functionality of the path-reversed calculation is greatly increased by extension to photoelectron diffraction for crystal surfaces with many atoms per unit cell [4]. The results are essentially indistinguishable from those of a conventional forward-path calculation. Application to photoelectron diffraction for 955 eV O 1s emission from a MgO(001) surface shows good agreement with experiment.

Pauli, Mark Daniel

218

Damage threshold investigation using grazing incidence irradiation by hard x-ray free electron laser  

NASA Astrophysics Data System (ADS)

X-ray free electron lasers (XFELs) with intense and ultra-short pulse X-rays possibly induce damage to optical elements. We investigated the damage thresholds of optical materials by using focusing XFEL beams with sufficient power density for studying ablation phenomena. 1-?m focusing beams with 10 keV photon energy were produced at the XFEL facility SACLA (SPring-8 Angstrom Compact free electron LAser). The focusing beams irradiated samples of rhodium-coated substrate, which is used in X-ray mirror optics, under grazing incident condition.

Koyama, T.; Yumoto, H.; Tono, K.; Sato, T.; Togashi, T.; Inubushi, Y.; Katayama, T.; Kim, J.; Matsuyama, S.; Mimura, H.; Yabashi, M.; Yamauchi, K.; Ohashi, H.

2013-09-01

219

Methods development for diffraction and spectroscopy studies of metalloenzymes at X-ray free-electron lasers.  

PubMed

X-ray free-electron lasers (XFELs) open up new possibilities for X-ray crystallographic and spectroscopic studies of radiation-sensitive biological samples under close to physiological conditions. To facilitate these new X-ray sources, tailored experimental methods and data-processing protocols have to be developed. The highly radiation-sensitive photosystem II (PSII) protein complex is a prime target for XFEL experiments aiming to study the mechanism of light-induced water oxidation taking place at a Mn cluster in this complex. We developed a set of tools for the study of PSII at XFELs, including a new liquid jet based on electrofocusing, an energy dispersive von Hamos X-ray emission spectrometer for the hard X-ray range and a high-throughput soft X-ray spectrometer based on a reflection zone plate. While our immediate focus is on PSII, the methods we describe here are applicable to a wide range of metalloenzymes. These experimental developments were complemented by a new software suite, cctbx.xfel. This software suite allows for near-real-time monitoring of the experimental parameters and detector signals and the detailed analysis of the diffraction and spectroscopy data collected by us at the Linac Coherent Light Source, taking into account the specific characteristics of data measured at an XFEL. PMID:24914169

Kern, Jan; Hattne, Johan; Tran, Rosalie; Alonso-Mori, Roberto; Laksmono, Hartawan; Gul, Sheraz; Sierra, Raymond G; Rehanek, Jens; Erko, Alexei; Mitzner, Rolf; Wernet, Phillip; Bergmann, Uwe; Sauter, Nicholas K; Yachandra, Vittal; Yano, Junko

2014-07-17

220

Artificial neural networks for plasma x-ray spectroscopic analysis  

SciTech Connect

Modern diagnostic instrumentation produces a vast amount of data that often requires substantial analysis efforts. New methods are needed to improve the efficiency of the analysis process. Artificial neural networks have been applied to a variety of signal processing and image recognition problems. The feed-forward, back-propagation technique is well suited for the analysis of scientific laboratory data, which is viewed as a pattern-matching problem. We summarize the concepts and algorithms as implemented on a personal computer, and illustrate the method using a nonlocal thermodynamic equilibrium theoretical atomic physics model for {ital k}-shell x-ray spectroscopy of a high density, high temperature aluminum plasma. Extensions to other types of spectroscopy data analysis are discussed.

Larsen, J.T. (Cascade Applied Sciences, Inc., P. O. Box 4477, Boulder, Colorado 80306 (United States)); Morgan, W.L. (Kinema Research, 18720 Autumn Way, Monument, Colorado 80132 (United States)); Goldstein, W.H. (Lawrence Livermore National Laboratory, Livermore, California 94550 (United States))

1992-10-01

221

Femtosecond X-Ray Free Electron Laser Pulse Duration Measurement from Spectral Correlation Function  

SciTech Connect

We present a novel method for measuring the duration of femtosecond x-ray pulses from self-amplified spontaneous emission free electron lasers by performing statistical analysis in the spectral domain. Analytical expressions of the spectral correlation function were derived in the linear regime to extract both the pulse duration and the spectrometer resolution. Numerical simulations confirmed that the method can be also used in the nonlinear regime. The method was demonstrated experimentally at the Linac Coherent Light Source by measuring pulse durations down to 13 fs FWHM.

Lutman, A. A

2012-04-17

222

Processing and quantification of x-ray energy dispersive spectra in the Analytical Electron Microscope  

SciTech Connect

Spectral processing in x-ray energy dispersive spectroscopy deals with the extraction of characteristic signals from experimental data. In this text, the four basic procedures for this methodology are reviewed and their limitations outlined. Quantification, on the other hand, deals with the interpretation of the information obtained from spectral processing. Here the limitations are for the most part instrumental in nature. The prospects of higher voltage operation does not, in theory, present any new problems and may in fact prove to be more desirable assuming that electron damage effects do not preclude analysis. 28 refs., 6 figs.

Zaluzec, N.J.

1988-08-01

223

Free-electron lasers: Fully coherent soft X-rays at FERMI  

NASA Astrophysics Data System (ADS)

The Italian free-electron laser, FERMI, now generates coherent soft X-rays in the water window (2.3-4.4 nm) by two-stage frequency upconversion of ultraviolet seed laser pulses using the 'fresh bunch' technique.

Hara, Toru

2013-11-01

224

Controlled Betatron X-Ray Radiation from Tunable Optically Injected Electrons  

NASA Astrophysics Data System (ADS)

The features of Betatron x-ray emission produced in a laser-plasma accelerator are closely linked to the properties of the relativistic electrons which are at the origin of the radiation. While in interaction regimes explored previously the source was by nature unstable, following the fluctuations of the electron beam, we demonstrate in this Letter the possibility to generate x-ray Betatron radiation with controlled and reproducible features, allowing fine studies of its properties. To do so, Betatron radiation is produced using monoenergetic electrons with tunable energies from a laser-plasma accelerator with colliding pulse injection [J. Faure , Nature (London) 444, 737 (2006)].NATUAS0028-083610.1038/nature05393 The presented study provides evidence of the correlations between electrons and x-rays, and the obtained results open significant perspectives toward the production of a stable and controlled femtosecond Betatron x-ray source in the keV range.

Corde, S.; Phuoc, K. Ta; Fitour, R.; Faure, J.; Tafzi, A.; Goddet, J. P.; Malka, V.; Rousse, A.

2011-12-01

225

Controlled Betatron X-Ray Radiation from Tunable Optically Injected Electrons  

SciTech Connect

The features of Betatron x-ray emission produced in a laser-plasma accelerator are closely linked to the properties of the relativistic electrons which are at the origin of the radiation. While in interaction regimes explored previously the source was by nature unstable, following the fluctuations of the electron beam, we demonstrate in this Letter the possibility to generate x-ray Betatron radiation with controlled and reproducible features, allowing fine studies of its properties. To do so, Betatron radiation is produced using monoenergetic electrons with tunable energies from a laser-plasma accelerator with colliding pulse injection [J. Faure et al., Nature (London) 444, 737 (2006)]. The presented study provides evidence of the correlations between electrons and x-rays, and the obtained results open significant perspectives toward the production of a stable and controlled femtosecond Betatron x-ray source in the keV range.

Corde, S.; Phuoc, K. Ta; Fitour, R.; Faure, J.; Tafzi, A.; Goddet, J. P.; Malka, V.; Rousse, A. [Laboratoire d'Optique Appliquee, ENSTA ParisTech - CNRS UMR7639 - Ecole Polytechnique, Chemin de la Huniere, 91761 Palaiseau (France)

2011-12-16

226

Impact of ultrafast electronic damage in single-particle x-ray imaging experiments.  

PubMed

In single-particle coherent x-ray diffraction imaging experiments, performed at x-ray free-electron lasers (XFELs), samples are exposed to intense x-ray pulses to obtain single-shot diffraction patterns. The high intensity induces electronic dynamics on the femtosecond time scale in the system, which can reduce the contrast of the obtained diffraction patterns and adds an isotropic background. We quantify the degradation of the diffraction pattern from ultrafast electronic damage by performing simulations on a biological sample exposed to x-ray pulses with different parameters. We find that the contrast is substantially reduced and the background is considerably strong only if almost all electrons are removed from their parent atoms. This happens at fluences of at least one order of magnitude larger than provided at currently available XFEL sources. PMID:23214818

Lorenz, U; Kabachnik, N M; Weckert, E; Vartanyants, I A

2012-11-01

227

Fast Electron Spatial Temperature Distribution Studied by X-Ray 2D Imaging  

NASA Astrophysics Data System (ADS)

We present the experimental and numerical results of two-dimensional x-ray imaging due to fast electron transport in a solid target. A 40-?m-thick copper film target is irradiated by a 100 mJ, 50 fs normal incident laser pulse. The full width at half maximum of the x-ray photon dose is 25 ?m, and the divergence angle of fast electrons is 25°–30°, which is detected by the pin-hole x-ray imaging technique. The target surface plasma layer is compressed by a ponderomotive force into a depth of 0.2?. The plasma wave accompanied by fast electrons transporting into the target is studied by dividing the plasma into layers in a radial direction. A narrow fast electron channel, which is approximately 8 ?m–10 ?m in width, mainly contributes to the x-ray dose.

Tian, Ye; Wang, Wen-Tao; Xia, Chang-Quan; Wang, Cheng; Xu, Yi; Li, Wen-Tao; Qi, Rong; Zhang, Zhi-Jun; Liang, Hong; Yu, Chang-Hai; Leng, Yu-Xin; Liu, Jian-Sheng

2014-05-01

228

Entangled valence electron-hole dynamics revealed by stimulated attosecond x-ray Raman scattering  

SciTech Connect

We show that broadband x-ray pulses can create wavepackets of valence electrons and holes localized in the vicinity of a selected atom (nitrogen, oxygen or sulfur in cysteine) by resonant stimulated Raman scattering. The subsequent dynamics reveals highly correlated motions of entangled electrons and hole quasiparticles. This information goes beyond the time-dependent total charge density derived from x-ray diffraction.

Healion, Daniel; Zhang, Yu; Biggs, Jason D.; Govind, Niranjan; Mukamel, Shaul

2012-09-06

229

Entangled Valence Electron-Hole Dynamics Revealed by Stimulated Attosecond X-ray Raman Scattering  

PubMed Central

We show that broadband x-ray pulses can create wavepackets of valence electrons and holes localized in the vicinity of a selected atom (nitrogen, oxygen or sulfur in cysteine) by stimulated resonant Raman scattering. The subsequent dynamics reveals highly correlated motions of entangled electrons and hole quasiparticles. This information goes beyond the time-dependent total charge density derived from x-ray diffraction.

Healion, Daniel; Zhang, Yu; Biggs, Jason D.; Govind, Niranjan

2012-01-01

230

Pair production from vacuum at the focus of an X-ray free electron laser  

Microsoft Academic Search

There are definite plans for the construction of X-ray free electron lasers (FEL), both at DESY, where the so-called XFEL is part of the design of the electron–positron linear collider TESLA, as well as at SLAC, where the so-called Linac Coherent Light Source (LCLS) has been proposed. Such an X-ray laser would allow for high-field science applications: one could make

A. Ringwald

2001-01-01

231

X-Ray Based Subpicosecond Electron Bunch Characterization Using 90° Thomson Scattering  

Microsoft Academic Search

X rays produced by 90° Thomson scattering of a femtosecond, near infrared, terawatt laser pulse of a 50 MeV electron beam are shown to be an effective diagnostic to measure transverse and longitudinal density distributions of an electron beam ( e beam) with subpicosecond time resolution. The laser beam was focused onto the e-beam waist, generating 30 keV x rays

W. P. Leemans; R. W. Schoenlein; P. Volfbeyn; A. H. Chin; T. E. Glover; P. Balling; M. Zolotorev; K. J. Kim; S. Chattopadhyay; C. V. Shank

1996-01-01

232

Early response of free airway cells to “amosite”: A correlated study using electron microscopy and energy dispersive x-ray analysis  

Microsoft Academic Search

The acute response of free airway cells following an intratracheal injection of “amosite” was studied by light microscopy,\\u000a electron microscopy and energy dispersive analysis. It was determined that the use of fixative as a lavage fluid provided\\u000a a superior level of morphological information. The free cell population consisted of macrophages, neutrophils, eosinophils,\\u000a lymphocytes and monocytes. The early phagocytic response (2

Ronald F. Dodson; Marion Glenn Williams; George A. Hurst

1979-01-01

233

X-ray analysis of wurtzite-type CoO(111) films on Ir(001): Correlation of structure, stress, electronic, and magnetic properties  

NASA Astrophysics Data System (ADS)

We present a surface x-ray diffraction study in combination with stress experiments and ab initio calculations to investigate the structure and magnetic properties of 1.6 and 2.0 bilayer thick CoO(111) films grown on Ir(001). The CoO films grow in a wurtzite-like structure characterized by reduced distances between cobalt and oxygen atoms within one bilayer. The double-bilayer film is under tensile stress of +2.1 N/m which can be quantitatively attributed to epitaxial misfit and excludes the presence of significant Coulomb interactions. First-principles calculations reveal that the CoO films are metallic and that the magnetic order is noncollinear.

Roy, Sumalay; Meyerheim, H. L.; Mohseni, K.; Tian, Z.; Sander, D.; Hoffmann, M.; Adeagbo, W.; Ernst, A.; Hergert, W.; Felici, R.; Kirschner, J.

2014-04-01

234

Nanostructure Analysis using Coherent X-ray Diffraction  

NASA Astrophysics Data System (ADS)

X-ray crystallography can routinely determine the atomic structure of crystalline materials. The method can be extended to non-crystalline materials by using coherent X-ray diffraction. In X-ray diffraction microscopy, coherent X-ray diffraction patterns are sampled finely enough to satisfy the oversampling condition for solving the phase problem, and the iterative phase retrieval method is used for the sample image reconstruction. Recently, we succeeded in three-dimensional visualization of an unstained human chromosome by X-ray diffraction microscopy. It is the first hard X-ray tomography for cellular organelles. The reconstructed images revealed the internal axial structure, demonstrating an excellent image-contrast of the method.

Nishino, Yoshinori

235

Bayesian Multiscale Analysis of X-Ray Jet Features in High Redshift Quasars  

NASA Astrophysics Data System (ADS)

X-ray emission of powerful quasar jets may be a result of the inverse Compton (IC) process in which the Cosmic Microwave Background (CMB) photons gain energy by interactions with the jet’s relativistic electrons. However, there is no definite evidence that IC/CMB process is responsible for the observed X-ray emission of large scale jets. A step toward understanding the X-ray emission process is to study the Radio and X-ray morphologies of the jet. We implement a sophisticated Bayesian image analysis program, Low-count Image Reconstruction and Analysis (LIRA) (Esch et al. 2004; Conners & van Dyk 2007), to analyze jet features in 11 Chandra images of high redshift quasars (z ~ 2 - 4.8). Out of the 36 regions where knots are visible in the radio jets, nine showed detectable X-ray emission. We measured the ratios of the X-ray and radio luminosities of the detected features and found that they are consistent with the CMB radiation relationship. We derived a range of the bulk lorentz factor (?) for detected jet features under the CMB jet emission model. There is no discernible trend of ? with redshift within the sample. The efficiency of the X-ray emission between the detected jet feature and the corresponding quasar also shows no correlation with redshift. This work is supported in part by the National Science Foundation REU and the Department of Defense ASSURE programs under NSF Grant no.1262851 and by the Smithsonian Institution, and by NASA Contract NAS8-39073 to the Chandra X-ray Center (CXC). This research has made use of data obtained from the Chandra Data Archive and Chandra Source Catalog, and software provided by the CXC in the application packages CIAO, ChIPS, and Sherpa. We thank Teddy Cheung for providing the VLA radio images. Connors, A., & van Dyk, D. A. 2007, Statistical Challenges in Modern Astronomy IV, 371, 101 Esch, D. N., Connors, A., Karovska, M., & van Dyk, D. A. 2004, ApJ, 610, 1213

McKeough, Kathryn; Siemiginowska, A.; Kashyap, V.; Stein, N.

2014-01-01

236

Theory of time-resolved nonresonant x-ray scattering for imaging ultrafast coherent electron motion  

NASA Astrophysics Data System (ADS)

Future ultrafast x-ray light sources might image ultrafast coherent electron motion in real space and in real time. For a rigorous understanding of such an imaging experiment, we extend the theory of nonresonant x-ray scattering to the time domain. The role of energy resolution of the scattering detector is investigated in detail. We show that time-resolved nonresonant x-ray scattering with no energy resolution offers an opportunity to study time-dependent electronic correlations in nonequilibrium quantum systems. Furthermore, our theory presents a unified description of ultrafast x-ray scattering from electronic wave packets and the dynamical imaging of ultrafast dynamics using inelastic x-ray scattering by Abbamonte and co-workers. We examine closely the relation of the scattering signal and the linear density response of electronic wave packets. Finally, we demonstrate that time-resolved x-ray scattering from a crystal consisting of identical electronic wave packets recovers the instantaneous electron density.

Dixit, Gopal; Slowik, Jan Malte; Santra, Robin

2014-04-01

237

ELECTRON MICROSCOPE AND LOW-ANGLE X-RAY DIFFRACTION STUDIES OF THE NERVE MYELIN SHEATH  

PubMed Central

1. A close correlation has been obtained between high resolution electron microscopy and low-angle x-ray diffraction studies of the myelin sheath of frog and rat peripheral and central nerves. Extensive studies were performed by application of both techniques to the same specimens, prepared for examination by OsO4 or KMnO4 fixation, and embedding either in methacrylate or in gelatin employing a new procedure. Controlled physical and chemical modifications of the myelin sheath prior to fixation were also investigated. 2. A correspondence was established between the layer spacings observed in electron micrographs and the fundamental radial repeating unit indicated by the low-angle x-ray diffraction patterns. The variations in relative intensities of the low-angle x-ray reflections could be related to the radial density distributions seen in the electron micrographs. 3. An analysis of the preparation procedures revealed that OsO4 fixation introduces a greater shrinkage of the layer spacings and more pronounced changes in the density distribution within the layers than KMnO4 fixation. The effects of methacrylate and gelatin embedding are described, and their relative merits considered in relation to the preservation of myelin structure by OsO4 fixation. 4. The experimental modifications introduced by freezing and thawing of fresh whole nerve are described, particularly the enhancement of the intermediate lines and the dissociation of the layer components in the myelin sheath. A characteristic collapsing of the radial period of the sheath is observed after subjecting fresh nerve trunks to prolonged and intense ultracentrifugation. 5. Controlled extraction of fresh nerve with acetone at 0°C., which preferentially removes cholesterol, produces characteristic, differentiated modifications of the myelin sheath structure. Electron microscopy reveals several types of modifications within a single preparation, including both expanded and collapsed layer systems, and internal rearrangements of the layer components. Alcohol extraction leads to a more extensive structural breakdown, but in certain areas collapsed layer systems can still be observed. The components of the lipide extracts could be identified by means of x-ray diffraction. These modifications emphasize the importance of cholesterol in the myelin structure, and disclose a resistance of the dense osmiophilic lines to lipide solvents. 6. The significance of these structures is discussed in relation to present concepts of the molecular organization of myelin. The available evidence is consistent with the suggestion that the primary site of osmium deposition is at the lipoprotein interfaces and that the light bands probably represent regions occupied by lipide chains. The electron microscope and x-ray diffraction data also indicate the possibility of a regular organization within the plane of the layers, probably involving units of 60 to 80 A. The myelin sheath is regarded as a favourable cell membrane model for detailed analysis by combined application of x-ray diffraction and electron microscopy.

Fernandez-moran, H.; Finean, J. B.

1957-01-01

238

X-ray free-electron lasers--present and future capabilities [Invited  

SciTech Connect

The Linac Coherent Light Source is now in operation as an X-ray free-electron laser (FEL) user facility. It produces coherent pulses of 550-10,000 eV X-rays of duration adjustable from <10 fs to 500 fs. Typical peak power is in excess of 20 GW. The facility will soon be joined by several X-ray FELs under construction around the world. This article will provide an abridged history of free-electron lasers, a description of some basic physics regarding free-electron laser light amplification, and an overview of the rapidly growing list of examples in which lasers will be used in the control and operation of X-ray FELs.

Galayda, John N.; Arthur, John; Ratner, Daniel F.; White, William E. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States)

2010-11-15

239

X-ray Free-Electron Lasers - Present and Future Capabilities [Invited  

SciTech Connect

The Linac Coherent Light Source is now in operation as an X-ray free-electron laser (FEL) user facility. It produces coherent pulses of 550-10,000 eV X-rays of duration adjustable from <10 fsto500 fs. Typical peak power is in excess of 20 GW. The facility will soon be joined by several X-ray FELs under construction around the world. This article will provide an abridged history of free-electron lasers, a description of some basic physics regarding free-electron laser light amplification, and an overview of the rapidly growing list of examples in which lasers will be used in the control and operation of X-ray FELs.

Galayda, John; Ratner, John Arthur:a Daniel F.; White, William E.; /SLAC

2011-11-16

240

Observation of pulsed x-ray trains produced by laser-electron Compton scatterings  

SciTech Connect

X-ray generation based on laser-electron Compton scattering is one attractive method to achieve a compact laboratory-sized high-brightness x-ray source. We have designed, built, and tested such a source; it combines a 50 MeV multibunch electron linac with a mode-locked 1064 nm laser stored and amplified in a Fabry-Perot optical cavity. We directly observed trains of pulsed x rays using a microchannel plate detector; the resultant yield was found to be 1.2x10{sup 5} Hz in good agreement with prediction. We believe that the result has demonstrated good feasibility of linac-based compact x-ray sources via laser-electron Compton scatterings.

Sakaue, Kazuyuki; Washio, Masakazu [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Araki, Sakae; Fukuda, Masafumi; Higashi, Yasuo; Honda, Yosuke; Omori, Tsunehiko; Taniguchi, Takashi; Terunuma, Nobuhiro; Urakawa, Junji [KEK (High Energy Accelerator Research Organization), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Sasao, Noboru [Department of Physics, Kyoto University, Sakyo, Kyoto 606-8502 (Japan)

2009-12-15

241

Two-colour hard X-ray free-electron laser with wide tunability  

NASA Astrophysics Data System (ADS)

Ultrabrilliant, femtosecond X-ray pulses from X-ray free-electron lasers (XFELs) have promoted the investigation of exotic interactions between intense X-rays and matters, and the observation of minute targets with high spatio-temporal resolution. Although a single X-ray beam has been utilized for these experiments, the use of multiple beams with flexible and optimum beam parameters should drastically enhance the capability and potentiality of XFELs. Here we show a new light source of a two-colour double-pulse (TCDP) XFEL in hard X-rays using variable-gap undulators, which realizes a large and flexible wavelength separation of more than 30% with an ultraprecisely controlled time interval in the attosecond regime. Together with sub-10-fs pulse duration and multi-gigawatt peak powers, the TCDP scheme enables us to elucidate X-ray-induced ultrafast transitions of electronic states and structures, which will significantly contribute to the advancement of ultrafast chemistry, plasma and astronomical physics, and quantum X-ray optics.

Hara, Toru; Inubushi, Yuichi; Katayama, Tetsuo; Sato, Takahiro; Tanaka, Hitoshi; Tanaka, Takashi; Togashi, Tadashi; Togawa, Kazuaki; Tono, Kensuke; Yabashi, Makina; Ishikawa, Tetsuya

2013-12-01

242

Two-colour hard X-ray free-electron laser with wide tunability.  

PubMed

Ultrabrilliant, femtosecond X-ray pulses from X-ray free-electron lasers (XFELs) have promoted the investigation of exotic interactions between intense X-rays and matters, and the observation of minute targets with high spatio-temporal resolution. Although a single X-ray beam has been utilized for these experiments, the use of multiple beams with flexible and optimum beam parameters should drastically enhance the capability and potentiality of XFELs. Here we show a new light source of a two-colour double-pulse (TCDP) XFEL in hard X-rays using variable-gap undulators, which realizes a large and flexible wavelength separation of more than 30% with an ultraprecisely controlled time interval in the attosecond regime. Together with sub-10-fs pulse duration and multi-gigawatt peak powers, the TCDP scheme enables us to elucidate X-ray-induced ultrafast transitions of electronic states and structures, which will significantly contribute to the advancement of ultrafast chemistry, plasma and astronomical physics, and quantum X-ray optics. PMID:24301682

Hara, Toru; Inubushi, Yuichi; Katayama, Tetsuo; Sato, Takahiro; Tanaka, Hitoshi; Tanaka, Takashi; Togashi, Tadashi; Togawa, Kazuaki; Tono, Kensuke; Yabashi, Makina; Ishikawa, Tetsuya

2013-01-01

243

Ultrashort x-ray pulse generation by electron beam slicing in storage rings  

NASA Astrophysics Data System (ADS)

We propose a new method to generate ultrashort x-ray pulses using focused short low energy (˜20 MeV) electron bunches to create short slices of electrons from the circulating electron bunches in a synchrotron radiation storage ring. When a low energy electron bunch crosses from the top of a high energy storage ring electron bunch, its Coulomb force will kick a short slice from the core of the storage ring electron bunch. The separated slices, when passing through an undulator, will radiate ultrashort x-ray pulses at about 160 fs. We discuss the advantages, challenges, and provide data which confirm the feasibility of this new method.

He, A.; Willeke, F.; Yu, L. H.

2014-04-01

244

Detection of soft X-rays with NEA III-V photocathodes. [Negative Electron Affinity X-ray detector for astronomy  

NASA Technical Reports Server (NTRS)

A description is presented of the results of tests on an X-ray photomultiplier containing a negative electron affinity (NEA) photocathode. This device makes it possible to investigate the response of the NEA photocathode to X-rays of various energies. The obtained data provide a basis for the determination of the photoelectron yield and energy resolution of the considered photocathode as a function of energy in the range from 0.8 to 3 keV. The investigation demonstrates the feasibility of using an NEA III-V photocathode for the detection of soft X-rays.

Bardas, D.; Kellogg, E.; Murray, S.; Enck, R., Jr.

1978-01-01

245

Multielement trace metal determination by electrodeposition, scanning electron microscopic X-ray fluorescence, and inductively coupled plasma mass spectrometry  

Microsoft Academic Search

Multielement analysis of multicomponent metallic electrodeposits is described, based on scanning electron microscopy with energy dispersive X-ray fluorescence (EDXRF) detection, followed by dissolution and inductively coupled plasma mass spectrometry (ICP-MS) detection. Application of the method is described for determination of trace elements in seawater, including Zn, Mn, Co, Cu, Cr, Ni, Fe, Cd, Pb, and Hg. These elements are simultaneously

Ngee Sing. Chong; Michael L. Norton; James L. Anderson

1990-01-01

246

OIM and X-ray texture analysis of melt-textured YBCO superconductors  

NASA Astrophysics Data System (ADS)

The results of two independent texture measurements on melt-textured Y-Ba-Cu-O (YBCO) high-Tc superconductors are compared with each other. The texture data are acquired by means of an X-ray based pole figure texture analysis and of a local texture analysis provided by an automated electron-backscatter diffraction (EBSD) or often called orientation imaging microscopy (OIM) analysis. As samples, we employ two different melt-textured YBCO samples; one fully processed (orthorhombic) and one without oxygen treatment (tetragonal). Pole figures in [103] direction are used to enable a direct comparison. We find a clear coincidence between the results obtained by the two measurement techniques on the melt-textured YBCO samples, however, the EBSD results are much more detailed, yielding the local grain orientation distribution and quantitative results of the grain or subgrain misorientation angles. Therefore, the EBSD measurements give informations which are not accessible by the X-ray texture analysis.

Koblischka-Veneva, A.; Koblischka, M. R.; Mücklich, F.; Murakami, M.

2005-03-01

247

Capillary Optics Based X-Ray Micro-Imaging Elemental Analysis  

NASA Astrophysics Data System (ADS)

A rapidly developed during the last few years micro-X-ray fluorescence spectrometry (?XRF) is a promising multi-elemental technique for non-destructive analysis. Typically it is rather hard to perform laboratory ?XRF analysis because of the difficulty of producing an original small-size X-ray beam as well as its focusing. Recently developed for X-ray beam focusing polycapillary optics offers laboratory X-ray micro probes. The combination of polycapillary lens and fine-focused micro X-ray tube can provide high intensity radiation flux on a sample that is necessary in order to perform the elemental analysis. In comparison to a pinhole, an optimized "X-ray source-op tics" system can result in radiation density gain of more than 3 orders by the value. The most advanced way to get that result is to use the confocal configuration based on two X-ray lenses, one for the fluorescence excitation and the other for the detection of secondary emission from a sample studied. In case of X-ray capillary microfocusing a ?XRF instrument designed in the confocal scheme allows us to obtain a 3D elemental mapping. In this work we will show preliminary results obtained with our prototype, a portable X-ray microscope for X-ray both imaging and fluorescence analysis; it enables ?XRF elemental mapping simultaneously with X-ray imaging. A prototype of compact XRF spectrometer with a spatial resolution less than 100 ?m has been designed.

Hampai, D.; Dabagov, S. B.; Cappuccio, G.; Longoni, A.; Frizzi, T.; Cibin, G.

2010-04-01

248

PROS: An IRAF based system for analysis of x ray data  

NASA Technical Reports Server (NTRS)

PROS is an IRAF based software package for the reduction and analysis of x-ray data. The use of a standard, portable, integrated environment provides for both multi-frequency and multi-mission analysis. The analysis of x-ray data differs from optical analysis due to the nature of the x-ray data and its acquisition during constantly varying conditions. The scarcity of data, the low signal-to-noise ratio and the large gaps in exposure time make data screening and masking an important part of the analysis. PROS was developed to support the analysis of data from the ROSAT and Einstein missions but many of the tasks have been used on data from other missions. IRAF/PROS provides a complete end-to-end system for x-ray data analysis: (1) a set of tools for importing and exporting data via FITS format -- in particular, IRAF provides a specialized event-list format, QPOE, that is compatible with its IMAGE (2-D array) format; (2) a powerful set of IRAF system capabilities for both temporal and spatial event filtering; (3) full set of imaging and graphics tasks; (4) specialized packages for scientific analysis such as spatial, spectral and timing analysis -- these consist of both general and mission specific tasks; and (5) complete system support including ftp and magnetic tape releases, electronic and conventional mail hotline support, electronic mail distribution of solutions to frequently asked questions and current known bugs. We will discuss the philosophy, architecture and development environment used by PROS to generate a portable, multimission software environment. PROS is available on all platforms that support IRAF, including Sun/Unix, VAX/VMS, HP, and Decstations. It is available on request at no charge.

Conroy, M. A.; Deponte, J.; Moran, J. F.; Orszak, J. S.; Roberts, W. P.; Schmidt, D.

1992-01-01

249

Analysis of urinary stone constituents using powder X-ray diffraction and FT-IR  

Microsoft Academic Search

Constituents of urinary stones obtained from various patients from western part of India, which is a highly urinary stone\\u000a disease-prone area, have been analysed. Eight stones from four patients were collected through urologists and have been analysed\\u000a using powder X-ray diffraction and FT-IR. Thermogravimetric analysis (TGA) and scanning electron microscopic (SEM) image of\\u000a selected samples were also carried out. The

Pragnya A. Bhatt; Parimal Paul

2008-01-01

250

Wavelength-dispersive spectrometer for X-ray microfluorescence analysis at the X-ray microscopy beamline ID21 (ESRF)  

PubMed Central

The development of a wavelength-dispersive spectrometer for microfluorescence analysis at the X-ray Microscopy ID21 beamline of the European Synchrotron Radiation Facility (ESRF) is reported. The spectrometer is based on a polycapillary optic for X-ray fluorescence collection and is operated in a flat-crystal geometry. The design considerations as well as operation characteristics of the spectrometer are presented. The achieved performances, in particular the energy resolution, are compared with the results of Monte Carlo simulations. Further improvement in the energy resolution, down to ?eV range, by employing a double-crystal geometry is examined. Finally, examples of applications requiring both spatial and spectral resolutions are presented.

Szlachetko, J.; Cotte, M.; Morse, J.; Salome, M.; Jagodzinski, P.; Dousse, J.-Cl.; Hoszowska, J.; Kayser, Y.; Susini, J.

2010-01-01

251

Wavelength-dispersive spectrometer for X-ray microfluorescence analysis at the X-ray Microscopy beamline ID21 (ESRF).  

PubMed

The development of a wavelength-dispersive spectrometer for microfluorescence analysis at the X-ray Microscopy ID21 beamline of the European Synchrotron Radiation Facility (ESRF) is reported. The spectrometer is based on a polycapillary optic for X-ray fluorescence collection and is operated in a flat-crystal geometry. The design considerations as well as operation characteristics of the spectrometer are presented. The achieved performances, in particular the energy resolution, are compared with the results of Monte Carlo simulations. Further improvement in the energy resolution, down to approximately eV range, by employing a double-crystal geometry is examined. Finally, examples of applications requiring both spatial and spectral resolutions are presented. PMID:20400840

Szlachetko, J; Cotte, M; Morse, J; Salomé, M; Jagodzinski, P; Dousse, J-Cl; Hoszowska, J; Kayser, Y; Susini, J

2010-05-01

252

A 9 keV electron-impact liquid-gallium-jet x-ray source  

SciTech Connect

We demonstrate a high-brightness compact 9 keV electron-impact microfocus x-ray source based on a liquid-gallium-jet anode. A {approx}30 W, 50 kV electron gun is focused onto the {approx}20 m/s, 30 {mu}m diameter liquid-gallium-jet anode to produce an {approx}10 {mu}m full width at half maximum x-ray spot. The peak spectral brightness is >2x10{sup 10} photons/(s mm{sup 2} mrad{sup 2}x0.1% BW). Calculation and experiments show potential for increasing this brightness by approximately three orders of magnitude, making the source suitable for laboratory-scale x-ray crystallography and hard x-ray microscopy.

Otendal, M.; Tuohimaa, T.; Vogt, U.; Hertz, H. M. [Biomedical and X-Ray Physics, Department of Applied Physics, Royal Institute of Technology/Albanova, SE-10691 Stockholm (Sweden)

2008-01-15

253

Fully Coherent X-ray Pulses from a Regenerative Amplifier Free Electron Laser  

SciTech Connect

We propose and analyze a novel regenerative amplifier free electron laser (FEL) to produce fully coherent x-ray pulses. The method makes use of narrow-bandwidth Bragg crystals to form an x-ray feedback loop around a relatively short undulator. Self-amplified spontaneous emission (SASE) from the leading electron bunch in a bunch train is spectrally filtered by the Bragg reflectors and is brought back to the beginning of the undulator to interact repeatedly with subsequent bunches in the bunch train. The FEL interaction with these short bunches not only amplifies the radiation intensity but also broadens its spectrum, allowing for effective transmission of the x-rays outside the crystal bandwidth. The spectral brightness of these x-ray pulses is about two to three orders of magnitude higher than that from a single-pass SASE FEL.

Huang, Zhirong; Ruth, Ronald D.

2006-02-17

254

Multichord time-resolved electron temperature measurements by the x-ray absorber-foil method on TFTR  

SciTech Connect

Absorber foils have been installed in the TFTR X-Ray Imaging System to permit measurement of the electron temperature along 10 to 30 chords spaced at 5-12.5 cm with a time resolution of less than 100 ..mu..s. The technique uses the ratio of x-ray fluxes transmitted through two different foils. The ratio depends mainly on electron temperature. Simulations show that strong impurity line radiation can distort this ratio. To correct for these effects, special beryllium-scandium filters are employed to select the line-free region between 2 and 4.5 keV. Other filter pairs allow corrections for Fe L and Ni L line radiation as well as Ti K and Ni K emission. Good accuracy is also obtained with simple beryllium filters, provided that impurity corrections are incorporated in the analysis, taking line intensities from the x-ray pulse-height analysis diagnostic. A description of modeling calculations and a comparison of temperature values from this diagnostic with data from the x-ray pulse height analysis, the electron cyclotron emission, and the Thomson scattering diagnostics are presented. Several applications of the absorber foil electron temperature diagnostic on TFTR are discussed.

Kiraly, J.; Bitter, M.; Efthimion, P.; von Goeler, S.; Grek, B.; Hill, K.W.; Johnson, D.; McGuire, K.; Sauthoff, N.; Sesnic, S.

1985-09-01

255

X-Ray Diffraction Analysis of NLO Crystals: Traditional Applications and More New Opportunities  

NASA Technical Reports Server (NTRS)

Single crystal X-ray diffraction analysis is one of the more important methods for the molecular and crystal structure determination of matter and therefore it has a great importance in material science including design and engineering of different compounds with non-linear optical (NLO) properties. It was shown in our previous publications that this method provides unique information about molecular structure of NLO compounds, their crystal symmetry and crystal packing arrays, molecular conformation and geometries and many other structural and electronic characteristics that are important for understanding the nature of NLO properties of solids. A very new application of the X-ray diffraction method is related to analysis of the electron density distribution p(r) in crystals and some of its characteristics (atomic and group charges, dipole and higher multipole moments, etc.), that may be obtained directly form the diffraction measurements. In the present work, we will discuss our preliminary low temperature high-resolution X-ray data for the m-nitroaniline (mNA) single crystal (VI). This is one of the "classical" organic NLO materials and electron density distribution analysis in this simple compound has a great scientific interest.

Antipin, Mikhail Yu.; Clark, Ronald D.; Nesterov, Vladimir N.

1998-01-01

256

Electronic Excitations in Vanadium Oxide Phthalocyanine Studied via Resonant Soft X-ray Emission and Resonant Inelastic X-ray Scattering  

SciTech Connect

The electronic structure of the organic semiconductor vanadium oxide phthalocyanine has been studied using resonant inelastic X-ray scattering and X-ray emission spectroscopy. The vanadyl species in the films is shown to be highly localized, and good agreement between the measurements and a density functional calculation is obtained. Both dipole forbidden V 3d to V 3d*, and O 2p to V 3d* charge transfer transitions are observed, and explained in a local molecular orbital model.

Zhang,Y.; Wang, S.; Learmonth, T.; Plucinski, L.; Matsuura, A.; Bernardis, S.; ODonnell, C.; Downes, J.; Smith, K.

2005-01-01

257

Phase recovery and lensless imaging by iterative methods in optical, X-ray and electron diffraction.  

PubMed

Thomas Young's quantitative analysis of interference effects provided the confidence needed to revive the wave theory of light, and firmly established the concept of phase in optics. Phase plays a similarly fundamental role in matter-wave interferometry, for which the field-emission electron microscope provides ideal instrumentation. The wave-particle duality is vividly demonstrated by experimental 'Young's fringes' using coherent electron beams under conditions in which the flight time is less than the time between particle emission. A brief historical review is given of electron interferometry and holography, including the Aharonov-Bohm effect and the electron Sagnac interferometer. The simultaneous development of phase-contrast imaging at subnanometre spatial resolution has greatly deepened our understanding of atomic processes in biology, materials science and condensed-matter physics, while electron holography has become a routine tool for the mapping of electrostatic and magnetic fields in materials on a nanometre scale. The encoding of phase information in scattered farfield intensities is discussed, and non-interferometric, non-crystallographic methods for phase retrieval are reviewed in relationship to electron holography. Examples of phase measurement and diffraction-limited imaging using the hybrid input-output iterative algorithm are given, including simulations for soft X-ray imaging, and new experimental results for coherent electron and visible-light scattering. Image reconstruction is demonstrated from experimental electron and visible-light Fraunhofer diffraction patterns. The prospects this provides for lensless imaging using particles for which no lenses exist (such as neutrons, condensates, coherent atom beams and X-rays) are discussed. These new interactions can be expected to provide new information, perhaps, for example, in biology, with the advantage of less damage to samples. PMID:12804284

Spence, J C H; Weierstall, U; Howells, M

2002-05-15

258

Photoelectron dynamics in x-ray free-electron-laser diffractive imaging of biological samples.  

PubMed

X-ray free electron lasers hold the promise of enabling atomic-resolution diffractive imaging of single biological molecules. We develop a hybrid continuum-particle model to describe the x-ray induced damage and find that the photoelectron dynamics and electrostatic confinement strongly affect the time scale of the damage processes. These phenomena are not fully captured in hydrodynamic modeling approaches. PMID:23003992

Hau-Riege, Stefan P

2012-06-01

259

Comparison of the Effect of X-ray and Electron Beam Irradiation on Some Selected Spices  

Microsoft Academic Search

The effect of irradiation with X-rays and electron beams on the microbiological quality of white pepper, sweet red paprika and nutmeg was examined. Statistical analyses were performed on the data to interpret the results on coliforms, total mesophilic counts and thermophilic spores after irradiation with doses ranging from 0 to 10 kGy at different dose rates, 50 Gy\\/min for X-rays

Sabine Van Calenberg; Gauthier Vanhaelewyn; Oswald Van Cleemput; Freddy Callens; Wim Mondelaers; André Huyghebaert

1998-01-01

260

Inferring Electron Temperature of Shocked Liquid Deuterium Using Inelastic X-Ray Scattering  

Microsoft Academic Search

A laser-ablation--driven shock wave (12 Mbar) was launched in a planar liquid-deuterium target on OMEGA, and the shocked conditions were diagnosed using inelastic x-ray scattering. The electron temperature (Te) is inferred from the Doppler-broadened, Compton-downshifted peak of the noncollective x-ray scattering for Te > TFermi. For this purpose, a saran backlighter foil was irradiated with a group of tightly focused

S. P. Regan; P. B. Radha; T. R. Boehly; V. N. Goncharov; R. L. McCrory; D. D. Meyerhofer; T. C. Sangster; V. A. Smalyuk; K. Falk; G. Gregori; T. Doeppner; S. H. Glenzer; O. L. Landen

2009-01-01

261

Accurate macromolecular structures using minimal measurements from X-ray free-electron lasers.  

PubMed

X-ray free-electron laser (XFEL) sources enable the use of crystallography to solve three-dimensional macromolecular structures under native conditions and without radiation damage. Results to date, however, have been limited by the challenge of deriving accurate Bragg intensities from a heterogeneous population of microcrystals, while at the same time modeling the X-ray spectrum and detector geometry. Here we present a computational approach designed to extract meaningful high-resolution signals from fewer diffraction measurements. PMID:24633409

Hattne, Johan; Echols, Nathaniel; Tran, Rosalie; Kern, Jan; Gildea, Richard J; Brewster, Aaron S; Alonso-Mori, Roberto; Glöckner, Carina; Hellmich, Julia; Laksmono, Hartawan; Sierra, Raymond G; Lassalle-Kaiser, Benedikt; Lampe, Alyssa; Han, Guangye; Gul, Sheraz; DiFiore, Dörte; Milathianaki, Despina; Fry, Alan R; Miahnahri, Alan; White, William E; Schafer, Donald W; Seibert, M Marvin; Koglin, Jason E; Sokaras, Dimosthenis; Weng, Tsu-Chien; Sellberg, Jonas; Latimer, Matthew J; Glatzel, Pieter; Zwart, Petrus H; Grosse-Kunstleve, Ralf W; Bogan, Michael J; Messerschmidt, Marc; Williams, Garth J; Boutet, Sébastien; Messinger, Johannes; Zouni, Athina; Yano, Junko; Bergmann, Uwe; Yachandra, Vittal K; Adams, Paul D; Sauter, Nicholas K

2014-05-01

262

Femtosecond diffractive imaging with a soft-X-ray free-electron laser  

Microsoft Academic Search

Theory predicts that, with an ultrashort and extremely bright coherent X-ray pulse, a single diffraction pattern may be recorded from a large macromolecule, a virus or a cell before the sample explodes and turns into a plasma. Here we report the first experimental demonstration of this principle using the FLASH soft-X-ray free-electron laser. An intense 25fs, 4×1013Wcm-2 pulse, containing 1012

Henry N. Chapman; Anton Barty; Michael J. Bogan; Sébastien Boutet; Matthias Frank; Stefan P. Hau-Riege; Stefano Marchesini; Bruce W. Woods; Sasa Bajt; W. Henry Benner; Richard A. London; Elke Plönjes; Marion Kuhlmann; Rolf Treusch; Stefan Düsterer; Thomas Tschentscher; Jochen R. Schneider; Eberhard Spiller; Thomas Möller; Christoph Bostedt; Matthias Hoener; David A. Shapiro; Keith O. Hodgson; David van der Spoel; Florian Burmeister; Magnus Bergh; Carl Caleman; Gösta Huldt; M. Marvin Seibert; Filipe R. N. C. Maia; Richard W. Lee; Abraham Szöke; Nicusor Timneanu; Janos Hajdu

2006-01-01

263

XPCS at the European X-ray free electron laser facility  

Microsoft Academic Search

The European X-ray free electron laser source (XFEL) will provide highly brilliant (B>1033ph\\/s\\/mm2\\/mrad2\\/0.1% bw) and coherent X-ray beams. The pulse structure and the unprecedented brightness will allow one for the first time to study fast dynamics in the time domain, thus giving direct access to the dynamic response function S(Q,t), instead of S(Q,?), which is of central importance for a

G. Grübel; G. B. Stephenson; C. Gutt; H. Sinn; Th. Tschentscher; Hasylab

2007-01-01

264

Accurate macromolecular structures using minimal measurements from X-ray free-electron lasers  

PubMed Central

X-ray free-electron laser (XFEL) sources enable the use of crystallography to solve three-dimensional macromolecular structures under native conditions and free from radiation damage. Results to date, however, have been limited by the challenge of deriving accurate Bragg intensities from a heterogeneous population of microcrystals, while at the same time modeling the X-ray spectrum and detector geometry. Here we present a computational approach designed to extract statistically significant high-resolution signals from fewer diffraction measurements.

Hattne, Johan; Echols, Nathaniel; Tran, Rosalie; Kern, Jan; Gildea, Richard J.; Brewster, Aaron S.; Alonso-Mori, Roberto; Glockner, Carina; Hellmich, Julia; Laksmono, Hartawan; Sierra, Raymond G.; Lassalle-Kaiser, Benedikt; Lampe, Alyssa; Han, Guangye; Gul, Sheraz; DiFiore, Dorte; Milathianaki, Despina; Fry, Alan R.; Miahnahri, Alan; White, William E.; Schafer, Donald W.; Seibert, M. Marvin; Koglin, Jason E.; Sokaras, Dimosthenis; Weng, Tsu-Chien; Sellberg, Jonas; Latimer, Matthew J.; Glatzel, Pieter; Zwart, Petrus H.; Grosse-Kunstleve, Ralf W.; Bogan, Michael J.; Messerschmidt, Marc; Williams, Garth J.; Boutet, Sebastien; Messinger, Johannes; Zouni, Athina; Yano, Junko; Bergmann, Uwe; Yachandra, Vittal K.; Adams, Paul D.; Sauter, Nicholas K.

2014-01-01

265

Femtosecond Diffractive Imaging with a Soft-X-Ray Free-Electron Laser  

Microsoft Academic Search

Theory predicts that with an ultrashort and extremely bright coherent X-ray pulse, a single diffraction pattern may be recorded from a large macromolecule, a virus, or a cell before the sample explodes and turns into a plasma. Here we report the first experimental demonstration of this principle using the FLASH soft X-ray free-electron laser. An intense 25 fs, 4 x

Bogan; Michael James

2010-01-01

266

X-ray chemical imaging and the electronic structure of a single nanoplatelet Ni/graphene composite.  

PubMed

Chemical imaging and quantitative analysis of a single graphene nanoplatelet grown with Ni nanoparticles (Ni/graphene) has been performed by scanning transmission X-ray microscopy (STXM). Local electronic and chemical structure of Ni/graphene has been investigated by spatially resolved C, O K-edges and Ni L-edge X-ray absorption near edge structure (XANES) spectroscopy, revealing the covalent anchoring of Ni(0) on graphene. This study facilitates the understanding of the structure modification of host materials for hydrogen storage and offers a better understanding of interaction between Ni particles and graphene. PMID:24443723

Zhou, Chunyu; Wang, Jian; Szpunar, Jerzy A

2014-03-01

267

In Situ Mineralogical Analysis of Planetary Materials Using X-Ray Diffraction and X-Ray Fluorescence  

NASA Technical Reports Server (NTRS)

Remote observations of Mars have led scientists to believe that its early climate was similar to that of the early Earth, having had abundant liquid water and a dense atmosphere. One of the most fascinating questions of recent times is whether simple bacterial life developed on Mars (as it did on the Earth) during this early element period. Analyses of SNC meteorites have broadened considerably our knowledge of the chemistry of certain types of Martian rocks, underscoring the tantalizing possibility of early hydrothermal systems and even of ancient bacterial life. Detailed analyses of SNC meteorites in Terrestrial laboratories utilize the most sophisticated organic, isotopic and microscopic techniques in existence. Indeed; it is unlikely that the key biogenic indicators used in McKay et al (ibid) could be identified by a remote instrument on the surface of Mars. As a result, it is probable that any robotic search for evidence of an ancient Martian biosphere will have as its focus the identification of key minerals in likely host rocks rather than the direct detection of organic or isotopic biomarkers. Even on a sample return mission, mineralogical screening will be utilized to choose the most likely candidate rocks. X-ray diffraction (XRD) is the only technique that can provide a direct determination of the crystal structures of the phases present within a sample. When many different crystalline phases are present, quantitative analysis is better constrained if used in conjunction with a determination of elemental composition, obtainable by X-ray fluorescence (XRF) using the same X-ray source as for XRD. For planetary surface analysis, a remote instrument combining XRD and XRF could be used for mineralogical characterization of both soils and rocks. We are designing a remote XRD/XRF instrument with this objective in mind. The instrument concept pays specific attention to constraints in sample preparation, weight, volume, power, etc. Based on the geometry of a pinhole camera (transmission geometry, flat two-dimensional detector perpendicular to the direct beam), the instrument (which we call CHEMIN, for Chemistry and Mineralogy) uses an X-ray sensitive CCD detector which will allow concurrent positional and energy-dispersive analysis of collected photons. Thus XRF (energy) and XRD (geometry) analysis of transmitted X-rays will be performed at the same time. Tests performed with single minerals and simple mixtures give promising results. Refinements of the prototype promise interpretable results on complex samples.

Sarrazin, P.; Blake, D.; Vaniman, D.; Chang, Sherwood (Technical Monitor)

1996-01-01

268

X-RAY NONLINEAR OPTICAL PROCESSES IN ATOMS USING A SELF-AMPLIFIED SPONTANEOUS EMISSION FREE-ELECTRON LASER  

SciTech Connect

X-ray free electron lasers (xFEL) will open new avenues to the virtually unexplored territory of non-linear interactions of x rays with matter. Initially xFELs will be based on the principle of self-amplified spontaneous emission (SASE). Each SASE pulse consists of a number of coherent intensity spikes of random amplitude, i.e. the process is chaotic and pulses are irreproducible. The coherence time of SASE xFELs will be a few femtoseconds for a photon energy near 1 keV. The importance of coherence properties of light in non-linear optical processes was theoretically discovered in the early 1960s. In this contribution we will illustrate the impact of field chaoticity on x-ray non-linear optical processes on neon for photon energies around 1 keV and intensities up to 10{sup 18} W/cm{sup 2}. Resonant and non-resonant processes are discussed. The first process to be addressed is the formation of a double-core hole in neon by photoionization with x rays above 1.25 keV energy. In contrast to the long-wavelength regime, non-linear optical processes in the x-ray regime are characterized in general by sequential single-photon single-electron interactions. Despite this fact, the sequential absorption of multiple x-ray photons depends on the statistical properties of the radiation field. Treating the x rays generated by a SASE FEL as fully chaotic, a quantum-mechanical analysis of inner-shell two-photon absorption is performed. By solving a system of time-dependent rate equations, we demonstrate that double-core hole formation in neon via x-ray two-photon absorption is enhanced by chaotic photon statistics. At an intensity of 10{sup 16} W/cm{sup 2}, the statistical enhancement is about 30%, much smaller than typical values in the optical regime. The second part of this presentation discusses the resonant Auger effect of atomic neon at the 1s-3p transition (at 867.1 eV). For low X-ray intensity, the excitation process 1s {yields} 3p in Neon can be treated perturbatively. The core-hole excited 1s{sup -1} 3p state is embedded in the continuum and decays via Auger-process on the timescale of approximately 5 fs. Increasing the x-ray intensity above 1.5 x 10{sup 18} W/cm{sup 2}, a peak intensity accessible with xFEL sources in the near future, x-ray induced emission from 3p back to 1s becomes possible, i.e. Rabi oscillations between these two levels can be induced. For the numerical analysis of this process, an effective two-level model, including a description of the resonant Auger decay process, is employed. The observation of x-ray-driven atomic populations dynamics in the time domain is challenging for chaotic xFEL pulses. In addition to requiring single-shot measurements, sub-femtosecond temporal resolution would be needed. The Rabi oscillations will, however, be imprinted on the kinetic energy distribution of the resonant Auger electron (see Fig. 1). Measuring the resonant Auger-electron line profile will provide information on both atomic population dynamics and x-ray pulse properties.

Rohringer, N

2008-08-08

269

Coherence-based transverse measurement of synchrotron x-ray radiation from relativistic laser-plasma interaction and of laser-accelerated electrons  

Microsoft Academic Search

Fresnel diffraction of x-ray beam from laser-plasma interaction shows incoherent-source diameter¿8 ¿m. Analysis shows this corresponds to accelerated electron profile in plasma agreeing with simulation.

Rahul C. Shah; F. Albert; K. Ta Phuoc; F. Burgy; J.-P. Rousseau; O. Shevchenko; D. Boschetto; A. Rousse; Alexander Pukhov; Sergei Kiselev

2007-01-01

270

Data processing software suite SITENNO for coherent X-ray diffraction imaging using the X-ray free-electron laser SACLA.  

PubMed

Coherent X-ray diffraction imaging is a promising technique for visualizing the structures of non-crystalline particles with dimensions of micrometers to sub-micrometers. Recently, X-ray free-electron laser sources have enabled efficient experiments in the `diffraction before destruction' scheme. Diffraction experiments have been conducted at SPring-8 Angstrom Compact free-electron LAser (SACLA) using the custom-made diffraction apparatus KOTOBUKI-1 and two multiport CCD detectors. In the experiments, ten thousands of single-shot diffraction patterns can be collected within several hours. Then, diffraction patterns with significant levels of intensity suitable for structural analysis must be found, direct-beam positions in diffraction patterns determined, diffraction patterns from the two CCD detectors merged, and phase-retrieval calculations for structural analyses performed. A software suite named SITENNO has been developed to semi-automatically apply the four-step processing to a huge number of diffraction data. Here, details of the algorithm used in the suite are described and the performance for approximately 9000 diffraction patterns collected from cuboid-shaped copper oxide particles reported. Using the SITENNO suite, it is possible to conduct experiments with data processing immediately after the data collection, and to characterize the size distribution and internal structures of the non-crystalline particles. PMID:24763651

Sekiguchi, Yuki; Oroguchi, Tomotaka; Takayama, Yuki; Nakasako, Masayoshi

2014-05-01

271

Soft X Ray Telescope (SXT) focus error analysis  

NASA Technical Reports Server (NTRS)

The analysis performed on the soft x-ray telescope (SXT) to determine the correct thickness of the spacer to position the CCD camera at the best focus of the telescope and to determine the maximum uncertainty in this focus position due to a number of metrology and experimental errors, and thermal, and humidity effects is presented. This type of analysis has been performed by the SXT prime contractor, Lockheed Palo Alto Research Lab (LPARL). The SXT project office at MSFC formed an independent team of experts to review the LPARL work, and verify the analysis performed by them. Based on the recommendation of this team, the project office will make a decision if an end to end focus test is required for the SXT prior to launch. The metrology and experimental data, and the spreadsheets provided by LPARL are used at the basis of the analysis presented. The data entries in these spreadsheets have been verified as far as feasible, and the format of the spreadsheets has been improved to make these easier to understand. The results obtained from this analysis are very close to the results obtained by LPARL. However, due to the lack of organized documentation the analysis uncovered a few areas of possibly erroneous metrology data, which may affect the results obtained by this analytical approach.

Ahmad, Anees

1991-01-01

272

Analysis of urinary stone components by x-ray coherent scatter: characterizing composition beyond laboratory x-ray diffractometry  

NASA Astrophysics Data System (ADS)

Monoenergetic x-ray diffraction (XRD) analysis is an established standard for the assessment of urinary stone composition. The inherent low energy of x-rays used (8 keV), however, restricts penetration depth and imposes a requirement for small powdered samples. A technique capable of producing detailed information regarding component structural arrangements in calculi non-destructively would provide clearer insights into causes of formation and subsequent growth and allow the selection of more appropriate courses of therapy. We describe a new method based on the detection of coherent scatter (CS) in stone components using polyenergetic x-rays (70 kVp) from diagnostic equipment. While the higher energy allows the analysis of intact calculi, the polyenergetic source causes an angular broadening of measured CS patterns. We show that it is possible to relate the polyenergetic (CS) and monoenergetic (XRD) measurements through a superposition integral of the monoenergetic XRD cross-section with a function representative of the polyenergetic spectrum used in CS. Experimentally acquired diffractometry cross-sections of the seven major urinary stone components were subjected to this operation, revealing good agreement of diffraction features with CS. Therefore, our CS analysis is sensitive to stone component structure, similar to conventional XRD analysis. This indicates that CS analysis can be used as a basis to classify urinary calculi by composition. The potential of identifying stone components non-destructively was demonstrated from a tomographic CS analysis of a stone-mimicking phantom. Tomographic composition maps were generated from CS patterns, showing the structural arrangement of multiple stone components within the phantom. CS analysis has the ability to detect components in the presence of many others. The ability to perform CS measurements in intact calculi would allow for the identification of stone structures critical to patient metaprophylaxis.

Davidson, Melanie T. M.; Batchelar, Deidre L.; Velupillai, Sujeevan; Denstedt, John D.; Cunningham, Ian A.

2005-08-01

273

Calculating the X-Ray Fluorescence from the Planet Mercury Due to High-Energy Electrons  

NASA Technical Reports Server (NTRS)

The least-studied terrestrial planet is Mercury due to its proximity to the Sun, which makes telescopic observations and spacecraft encounters difficult. Our lack of knowledge about Mercury should change in the near future due to the recent launching of MESSENGER, a Mercury orbiter. Another mission (BepiColombo) is currently being planned. The x-ray spectrometer on MESSENGER (and planned for BepiColombo) can characterize the elemental composition of a planetary surface by measuring emitted fluorescent x-rays. If electrons are ejected from an atom s inner shell by interaction with energetic particles such as photons, electrons, or ions, electrons from an outer shell can transfer to the inner shell. Characteristic x-rays are then emitted with energies that are the difference between the binding energy of the ion in its excited state and that of the ion in its ground state. Because each element has a unique set of energy levels, each element emits x-rays at a unique set of energies. Electrons and ions usually do not have the needed flux at high energies to cause significant x-ray fluorescence on most planetary bodies. This is not the case for Mercury where high-energy particles were detected during the Mariner 10 flybys. Mercury has an intrinsic magnetic field that deflects the solar wind, resulting in a bow shock in the solar wind and a magnetospheric cavity. Electrons and ions accelerated in the magnetosphere tend to follow its magnetic field lines and can impact the surface on Mercury s dark side Modeling has been done to determine if x-ray fluorescence resulting from the impact of high-energy electrons accelerated in Mercury's magnetosphere can be detected by MESSENGER. Our goal is to understand how much bulk chemical information can be obtained from x-ray fluorescence measurements on the dark side of Mercury.

Burbine, T. H.; Trombka, J. I.; Bergstrom, P. M., Jr.; Christon, S. P.

2005-01-01

274

Nonequilibrium electron dynamics in materials driven by high-intensity x-ray pulses  

NASA Astrophysics Data System (ADS)

We calculated the evolution of the electron system in solid-density matter irradiated by high-intensity x-ray pulses between 2 and 8 keV using molecular dynamics. For pulses shorter than 40 fs, the kinetic energy distribution of the electrons is highly nonthermal during and right after the pulse, and a large fraction of the absorbed x-ray energy resides with the fast photoelectrons which equilibrate on the timescale of the pulse length. The average ionization and electron temperature of the bulk of the electrons are significantly lower than their equilibrium values.

Hau-Riege, Stefan P.

2013-05-01

275

Total reflection X-ray fluorescence spectrometers for multielement analysis: status of equipment  

NASA Astrophysics Data System (ADS)

Multielement analysis by total reflection X-ray fluorescence spectrometry has evolved during two decades. At present commercial equipment is available for chemical analysis of all types of biological and mineral samples. The electronic industry has also benefited from scientific and technological developments in this field due to new instrumentation to determine contamination on the surface of silicon wafers (the equipment will not be covered in this paper). The basic components of the spectrometers can be summarized as follows: (a) excitation source; (b) geometric arrangement (optics) for collimation and monochromatization of the primary radiation; (c) X-ray detector; and (d) software for operation of the instrument, data acquisition and spectral deconvolution to determine the concentrations of the elements (quantitative analysis). As an optional feature one manufacturer offers a conventional 45° geometry for direct excitation. Personal communications of the author and commercial brochures available have allowed us to list the components used in TXRF for multielement analysis. Excitation source: high-power sealed X-ray tubes, output from 1300 to 3000 W, different mixed alloy anodes Mo/W are used but molybdenum, tungsten and copper are common; single anode metal ceramic low power X-ray tubes, output up to 40 W. Excitation systems can be customized according to the requirements of the laboratory. Detector: silicon-lithium drifted semiconductor detector liquid nitrogen cooled; or silicon solid state thermoelectrically cooled detector (silicon drift detector SDD and silicon-PIN diode detector). Optics: multilayer monochromator of silicon-tungsten, nickel-carbon or double multilayer monochromator. Electronics: spectroscopy amplifier, analog to digital converter adapted to a PC compatible computer with software in a Windows environment for the whole operation of the spectrometer and for qualitative/quantitative analysis of samples are standard features in the production of this instrument. The detection limits reported in the literature are presented; pricing, analytical capability, ease of operation, calibration and optical alignment as well as technical support are also discussed.

Ayala Jiménez, Rony E.

2001-11-01

276

Development of an X-ray pixel detector with multi-port charge-coupled device for X-ray free-electron laser experiments.  

PubMed

This paper presents development of an X-ray pixel detector with a multi-port charge-coupled device (MPCCD) for X-ray Free-Electron laser experiments. The fabrication process of the CCD was selected based on the X-ray radiation hardness against the estimated annual dose of 1.6 × 10(14) photon/mm(2). The sensor device was optimized by maximizing the full well capacity as high as 5 Me- within 50 ?m square pixels while keeping the single photon detection capability for X-ray photons higher than 6 keV and a readout speed of 60 frames/s. The system development also included a detector system for the MPCCD sensor. This paper summarizes the performance, calibration methods, and operation status. PMID:24689567

Kameshima, Takashi; Ono, Shun; Kudo, Togo; Ozaki, Kyosuke; Kirihara, Yoichi; Kobayashi, Kazuo; Inubushi, Yuichi; Yabashi, Makina; Horigome, Toshio; Holland, Andrew; Holland, Karen; Burt, David; Murao, Hajime; Hatsui, Takaki

2014-03-01

277

Development of an X-ray pixel detector with multi-port charge-coupled device for X-ray free-electron laser experiments  

NASA Astrophysics Data System (ADS)

This paper presents development of an X-ray pixel detector with a multi-port charge-coupled device (MPCCD) for X-ray Free-Electron laser experiments. The fabrication process of the CCD was selected based on the X-ray radiation hardness against the estimated annual dose of 1.6 × 1014 photon/mm2. The sensor device was optimized by maximizing the full well capacity as high as 5 Me- within 50 ?m square pixels while keeping the single photon detection capability for X-ray photons higher than 6 keV and a readout speed of 60 frames/s. The system development also included a detector system for the MPCCD sensor. This paper summarizes the performance, calibration methods, and operation status.

Kameshima, Takashi; Ono, Shun; Kudo, Togo; Ozaki, Kyosuke; Kirihara, Yoichi; Kobayashi, Kazuo; Inubushi, Yuichi; Yabashi, Makina; Horigome, Toshio; Holland, Andrew; Holland, Karen; Burt, David; Murao, Hajime; Hatsui, Takaki

2014-03-01

278

Time-resolved structural studies at synchrotrons and X-ray free electron lasers: opportunities and challenges  

PubMed Central

X-ray free electron lasers (XFELs) are potentially revolutionary X-ray sources because of their very short pulse duration, extreme peak brilliance and high spatial coherence, features that distinguish them from today’s synchrotron sources. We review recent time-resolved Laue diffraction and time-resolved wide angle X-ray scattering (WAXS) studies at synchrotron sources, and initial static studies at XFELs. XFELs have the potential to transform the field of time-resolved structural biology, yet many challenges arise in devising and adapting hardware, experimental design and data analysis strategies to exploit their unusual properties. Despite these challenges, we are confident that XFEL sources are poised to shed new light on ultrafast protein reaction dynamics.

Neutze, Richard; Moffat, Keith

2012-01-01

279

Time-resolved structural studies at synchrotrons and X-ray free electron lasers: opportunities and challenges.  

PubMed

X-ray free electron lasers (XFELs) are potentially revolutionary X-ray sources because of their very short pulse duration, extreme peak brilliance and high spatial coherence, features that distinguish them from today's synchrotron sources. We review recent time-resolved Laue diffraction and time-resolved wide angle X-ray scattering (WAXS) studies at synchrotron sources, and initial static studies at XFELs. XFELs have the potential to transform the field of time-resolved structural biology, yet many challenges arise in devising and adapting hardware, experimental design and data analysis strategies to exploit their unusual properties. Despite these challenges, we are confident that XFEL sources are poised to shed new light on ultrafast protein reaction dynamics. PMID:23021004

Neutze, Richard; Moffat, Keith

2012-10-01

280

Experimental demonstration of femtosecond two-color x-ray free-electron lasers.  

PubMed

With an eye toward extending optical wave-mixing techniques to the x-ray regime, we present the first experimental demonstration of a two-color x-ray free-electron laser at the Linac Coherent Light Source. We combine the emittance-spoiler technique with a magnetic chicane in the undulator section to control the pulse duration and relative delay between two intense x-ray pulses and we use differently tuned canted pole undulators such that the two pulses have different wavelengths as well. Two schemes are shown to produce two-color soft x-ray pulses with a wavelength separation up to ?1.9% and a controllable relative delay up to 40 fs. PMID:23581326

Lutman, A A; Coffee, R; Ding, Y; Huang, Z; Krzywinski, J; Maxwell, T; Messerschmidt, M; Nuhn, H-D

2013-03-29

281

Impulsive solar X-ray bursts: Bremsstrahlung radiation from a beam of electrons in the solar chromosphere and the total energy of solar flares  

NASA Technical Reports Server (NTRS)

Analysis of various aspects of impulsive X-ray bursts (IXB's) has lead to the consideration of a model where the X-rays are produced by bremsstrahlung radiation from a beam of electrons directed toward the photosphere. It was found that in general the X-ray spectrum from such a beam will fall off more rapidly than when the effect of the beaming of radiation is neglected. Furthermore, the spectral index of the resulting X-rays appears to increase by about unity for X-ray energies 100 kev, a fact which may explain the observed cutoff in the spectrum of the IXB's. It is also shown that in such a model there is sufficient energy in the form of nonthermal electrons to explain the total energy (approximately 10 to the 32nd power ergs) of a flare.

Petrosian, V.

1973-01-01

282

Internal conversion in energy dispersive X-ray analysis of actinide-containing materials.  

PubMed

The use of X-ray elemental analysis tools like energy dispersive X-ray (EDS) is described in the context of the investigation of nuclear materials. These materials contain radioactive elements, particularly alpha-decaying actinides that affect the quantitative EDS measurement by producing interferences in the X-ray spectra. These interferences originating from X-ray emission are the result of internal conversion by the daughter atoms from the alpha-decaying actinides. The strong interferences affect primarily the L X-ray lines from the actinides (in the typical energy range used for EDS analysis) and would require the use of the M lines. However, it is typically at the energy of the actinide's M lines that the interferences are dominant. The artifacts produced in the X-ray analysis are described and illustrated by some typical examples of analysis of actinide-bearing material. PMID:17490502

Wiss, Thierry; Thiele, Hartmut; Cremer, Bert; Ray, Ian

2007-06-01

283

Direct observation of unstained wet biological samples by scanning-electron generation X-ray microscopy  

SciTech Connect

Analytical tools of nanometre-scale resolution are indispensable in the fields of biology, physics and chemistry. One suitable tool, the soft X-ray microscope, provides high spatial resolution of visible light for wet specimens. For biological specimens, X-rays of water-window wavelength between carbon (284 eV; 4.3 nm) and oxygen (540 eV; 2.3 nm) absorption edges provide high-contrast imaging of biological samples in water. Among types of X-ray microscope, the transmission X-ray microscope using a synchrotron radiation source with diffractive zone plates offers the highest spatial resolution, approaching 15-10 nm. However, even higher resolution is required to measure proteins and protein complexes in biological specimens; therefore, a new type of X-ray microscope with higher resolution that uses a simple light source is desirable. Here we report a novel scanning-electron generation X-ray microscope (SGXM) that demonstrates direct imaging of unstained wet biological specimens. We deposited wet yeasts in the space between two silicon nitride (Si{sub 3}N{sub 4}) films. A scanning electron beam of accelerating voltage 5 keV and current 1.6 nA irradiates the titanium (Ti)-coated Si{sub 3}N{sub 4} film, and the soft X-ray signal from it is detected by an X-ray photodiode (PD) placed below the sample. The SGXM can theoretically achieve better than 5 nm resolution. Our method can be utilized easily for various wet biological samples of bacteria, viruses, and protein complexes.

Ogura, Toshihiko, E-mail: t-ogura@aist.go.jp [Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, Umezono, Tsukuba, Ibaraki 305-8568 (Japan)] [Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

2010-01-01

284

X-ray photoemission electron microscopy for the study of semiconductor materials  

SciTech Connect

Photoemission Electron Microscopy using X-rays (X-PEEM) is a novel combination of two established materials analysis techniques--PEEM using UV light, and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. This combination allows the study of elemental composition and bonding structure of the sample by NEXAFS spectroscopy with a high spatial resolution given by the microscope. A simple, two lens, 10 kV operation voltage PEEM has been used at the Stanford Synchrotron Radiation Laboratory and at the Advanced Light Source (ALS) in Berkeley to study various problems including materials of interest for the semiconductor industry. In the present paper we give a short overview over the method and the instrument which was used, and describe in detail a number of applications. These applications include the study of the different phases of titanium disilicide, various phases of boron nitride, and the analysis of small particles. A brief outlook is given on possible new fields of application of the PEEM technique, and the development of new PEEM instruments.

Anders, Simone; Stammler, Thomas; Padmore, Howard A. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720 (United States); Terminello, Louis J.; Jankowski, Alan F. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Stoehr, Joachim [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States); Diaz, Javier [Departamento de Fisic, Facultad de Ciencias, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo, 33007 (Spain); Cossy-Favre, Aline [EMPA, Duebendorf, Ueberlandstrasse 129, 8600 Duebendorf (Switzerland); Singh, Sangeet [Center for X-ray Lithography, University of Wisconsin-Madison, Stoughton, Wisconsin 53589 (United States)

1998-11-24

285

Ion Distribution in Roots of Barley Seedlings Measured by Electron Probe X-Ray Microanalysis 1  

PubMed Central

The distribution of ions, particularly K and Na, was studied in roots of barley seedlings grown on various ionic solutions. Analyses were made by means of electron probe x-ray microanalysis using frozen, fractured bulk specimens. By this technique, it was demonstrated that there can be variability in the ratio K/Na measured in the vacuoles of cortical cells, with this ratio often being lower in epidermal cells of the root than in the inner cortex. A sharp difference in the K/Na ratio was also found between cells of the endodermis and those of the adjacent cortex, and generally higher ratios of K/Na occurred in the stele than in the cortex. Estimation of the concentrations in the cytoplasm was at the limit of resolution of this technique, but it can be shown that the K/Na ratio in the cytoplasm was higher than that in the vacuole. In low salt roots, the K concentration in the cytoplasm was higher than that in the vacuoles. The results with the x-ray microprobe confirm other measurements based on flux analysis or analysis of small samples of the root. Images

Pitman, Michael G.; Lauchli, Andre; Stelzer, Ralf

1981-01-01

286

Compton scattering artifacts in electron excited X-ray spectra measured with a silicon drift detector.  

PubMed

Artifacts are the nemesis of trace element analysis in electron-excited energy dispersive X-ray spectrometry. Peaks that result from nonideal behavior in the detector or sample can fool even an experienced microanalyst into believing that they have trace amounts of an element that is not present. Many artifacts, such as the Si escape peak, absorption edges, and coincidence peaks, can be traced to the detector. Others, such as secondary fluorescence peaks and scatter peaks, can be traced to the sample. We have identified a new sample-dependent artifact that we attribute to Compton scattering of energetic X-rays generated in a small feature and subsequently scattered from a low atomic number matrix. It seems likely that this artifact has not previously been reported because it only occurs under specific conditions and represents a relatively small signal. However, with the advent of silicon drift detectors and their utility for trace element analysis, we anticipate that more people will observe it and possibly misidentify it. Though small, the artifact is not inconsequential. Under some conditions, it is possible to mistakenly identify the Compton scatter artifact as approximately 1% of an element that is not present. PMID:22067917

Ritchie, Nicholas W M; Newbury, Dale E; Lindstrom, Abigail P

2011-12-01

287

X-ray photoemission electron microscopy for the study of semiconductor materials  

SciTech Connect

Photoemission Electron Microscopy (PEEM) using X-rays is a novel combination of two established materials analysis techniques--PEEM using UV light, and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. This combination allows the study of elemental composition and bonding structure of the sample by NEXAFS spectroscopy with a high spatial resolution given by the microscope. A simple, two lens, 10 kV operation voltage PEEM has been used at the Stanford Synchrotron Radiation Laboratory and at the Advanced Light Source (ALS) in Berkeley to study various problems including materials of interest for the semiconductor industry. In the present paper the authors give a short overview over the method and the instrument which was used, and describe in detail a number of applications. These applications include the study of the different phases of titanium disilicide, various phases of boron nitride, and the analysis of small particles. A brief outlook is given on possible new fields of application of the PEEM technique, and the development of new PEEM instruments.

Anders, S.; Stammler, T.; Padmore, H. [Lawrence Berkeley National Lab., CA (United States). Advanced Light Source Div.; Terminello, L.J.; Jankowski, A.F. [Lawrence Livermore National Lab., CA (United States); Stohr, J. [IBM Almaden Research Center, San Jose, CA (United States); Diaz, J. [Univ. de Oviedo (Spain). Dept. de Fisica; Cossy-Gantner, A. [EMPA, Duebendorf (Germany)

1998-03-01

288

Development of suitable plastic standards for X-ray fluorescence analysis  

NASA Astrophysics Data System (ADS)

For the adoption of the EU directive "Restriction on use of certain Hazardous Substances" and "Waste Electrical and Electronic Equipment" using X-ray fluorescence analysis suitable standard materials are required. Plastic standards based on acrylonitrile-butadiene-styrene terpolymer, containing the regulated elements Br, Cd, Cr, Hg and Pb were developed and produced as granulates and solid bodies. The calibration materials were not generated as a dilution from one master batch but rather the element concentrations were distributed over nine independent calibration samples. This was necessary to enable inter-elemental corrections and empirical constant mass absorption coefficients. The produced standard materials are characterized by a homogenous element distribution, which is more than sufficient for X-ray fluorescence analysis. Concentrations for all elements except for Br could be determined by Inductively Coupled Plasma Atomic Emission Spectroscopy after microwave assisted digestion. The concentration of Br was determined by use of Neutron Activation Analysis at Hahn-Meitner-Institute in Berlin, Germany. The correlation of the X-ray fluorescence analysis measurements with the values determined using Inductively Coupled Plasma Atomic Emission Spectroscopy and Neutron Activation Analysis showed a very good linearity.

Mans, Christian; Hanning, Stephanie; Simons, Christoph; Wegner, Anne; Jan?en, Anton; Kreyenschmidt, Martin

2007-02-01

289

Digital filtering and analysis for a semiconductor X-ray detector data acquisition  

NASA Astrophysics Data System (ADS)

Pile-up distortion is a major drawback in X-ray spectroscopy at high count rate. Pulse width narrowing with shaping techniques can lead to the reduction of the pile-up distortion, but a low shaping time reduces the noise filtration and leads to a poor energy resolution. Thus, only a best compromise solution between the pile-up and the noise requirements is achievable. The hardware manipulation needed to adjust the parameters of the traditional electronic shaping amplifiers makes it uneasy to tests various settings in different conditions. Digital techniques can help to overcome such difficulties. A digital signal processing and analysis system for X-ray spectroscopy is described in this paper. The system processes the output signal of a Charge Sensitive Preamplifier (CSPA) connected to an X-ray semiconductor detector. The output CSPA signal is registered with a high speed ADC (sampling rate up to 100 MS/s, 14 bit resolution) and a fully digital shaping is performed off-line by a dedicated software instead of analog electronics. The software carries out the rest of data analysis (peak detection, pile-up recognition, rejection or correction) and finally calculates the photon count, constructs the spectrum and extracts other useful information. We processed the output signals of an Amptek ® XR-100 T CdTe detector used with mammographic X-ray beams. We developed the system with the LabVIEW ® platform. The software is characterized by a user friendly GUI which make it easier to change settings than traditional electronics.

Gerardi, Gaetano; Abbene, Leonardo; La Manna, Angelo; Fauci, Francesco; Raso, Giuseppe

2007-02-01

290

Runaway electron energy measurement using hard x-ray spectroscopy in "Damavand" tokamak.  

PubMed

Set of experiments has been developed to study existing runaway electrons in "Damavand" tokamak plasma upon characteristics of hard x-ray emissions produced by collision of the runaway electrons with the plasma particles and limiters. As a first step, spatial distribution of hard x-ray emissions on the equatorial plane of the torus was considered. Obtained spectra of hard x-ray emissions for different alignments of shielded detector indicate isotropic emissivity in the equatorial plane. This is in agreement with wide angle cone of bremsstrahlung radiations, deduced from the mean value of energy of the runaway electrons. The mean energy was calculated from the slope of the energy spectrum of hard x-ray photons. In the second stage in order to investigate time evolution of energy of the runaway electrons, similar technique were applied to obtain hard x-ray energy in every 3 ms intervals, from the beginning to the end of plasma. The mean energy of the runaway electrons increases during the ramp up phase and reaches its maximum between 3 and 9 ms after plasma formation. Also considering the time dependence of the counted photons in each energy range shows that energetic photons are emitted during the ramp up phase of the plasma current in Damavand tokamak. PMID:19191433

Rasouli, C; Iraji, D; Farahbod, A H; Akhtari, K; Rasouli, H; Modarresi, H; Lamehi, M

2009-01-01

291

Runaway electron energy measurement using hard x-ray spectroscopy in 'Damavand' tokamak  

SciTech Connect

Set of experiments has been developed to study existing runaway electrons in ''Damavand'' tokamak plasma upon characteristics of hard x-ray emissions produced by collision of the runaway electrons with the plasma particles and limiters. As a first step, spatial distribution of hard x-ray emissions on the equatorial plane of the torus was considered. Obtained spectra of hard x-ray emissions for different alignments of shielded detector indicate isotropic emissivity in the equatorial plane. This is in agreement with wide angle cone of bremsstrahlung radiations, deduced from the mean value of energy of the runaway electrons. The mean energy was calculated from the slope of the energy spectrum of hard x-ray photons. In the second stage in order to investigate time evolution of energy of the runaway electrons, similar technique were applied to obtain hard x-ray energy in every 3 ms intervals, from the beginning to the end of plasma. The mean energy of the runaway electrons increases during the ramp up phase and reaches its maximum between 3 and 9 ms after plasma formation. Also considering the time dependence of the counted photons in each energy range shows that energetic photons are emitted during the ramp up phase of the plasma current in Damavand tokamak.

Rasouli, C.; Farahbod, A. H.; Rasouli, H.; Lamehi, M. [School of Plasma Physics and Nuclear Fusion, Institute of Nuclear Science and Technology, AEOI, P.O. Box 14155-1339, Tehran (Iran, Islamic Republic of); Iraji, D. [Centre de Recherches en Physique des Plasmas, Association EURATOM-Confederation Suisse, Ecole Polytechnique Federale de Lausanne, CH-1015 (Switzerland); Akhtari, K. [Department of Physics, Sharif University of Technology, P.O. Box 11365-9161, Tehran (Iran, Islamic Republic of); Modarresi, H. [Department of Mechanical Engineering, Sharif University of Technology, P.O. Box 11365-9567, Tehran (Iran, Islamic Republic of)

2009-01-15

292

X-ray diagnostics of runaway electrons generated during nanosecond discharge in gas at elevated pressures  

SciTech Connect

The properties of high-energy runaway electrons generated during a nanosecond discharge in an air filled diode at pressures up to 3 x 10{sup 5} Pa were studied using x-ray absorption spectroscopy. The results of studies of the discharge at different pressures and with different lengths of cathode-anode gap allow an insight into the factors that influence the energy distribution of runaway electrons. Energy distribution functions for runaway electrons produced in particle-in-cell simulation were used to create the x-ray attenuation curves via a computer-assisted technique simulating the generation of x-ray by energetic electrons. The simulated attenuation curves were compared to experimental results.

Yatom, S.; Levko, D.; Gleizer, J. Z.; Vekselman, V.; Krasik, Ya. E. [Physics Department, Technion, Haifa 32000 (Israel)

2012-01-09

293

Deep inner-shell multiphoton ionization by intense x-ray free-electron laser pulses.  

PubMed

We have investigated multiphoton multiple ionization dynamics of xenon atoms using a new x-ray free-electron laser facility, SPring-8 Angstrom Compact free electron LAser (SACLA) in Japan, and identified that Xe(n+) with n up to 26 is produced at a photon energy of 5.5 keV. The observed high charge states (n?24) are produced via five-photon absorption, evidencing the occurrence of multiphoton absorption involving deep inner shells. A newly developed theoretical model, which shows good agreement with the experiment, elucidates the complex pathways of sequential electronic decay cascades accessible in heavy atoms. The present study of heavy-atom ionization dynamics in high-intensity hard-x-ray pulses makes a step forward towards molecular structure determination with x-ray free-electron lasers. PMID:23679721

Fukuzawa, H; Son, S-K; Motomura, K; Mondal, S; Nagaya, K; Wada, S; Liu, X-J; Feifel, R; Tachibana, T; Ito, Y; Kimura, M; Sakai, T; Matsunami, K; Hayashita, H; Kajikawa, J; Johnsson, P; Siano, M; Kukk, E; Rudek, B; Erk, B; Foucar, L; Robert, E; Miron, C; Tono, K; Inubushi, Y; Hatsui, T; Yabashi, M; Yao, M; Santra, R; Ueda, K

2013-04-26

294

High-gain X-ray free electron laser by beat-wave terahertz undulator  

NASA Astrophysics Data System (ADS)

The THz undulator has a higher gain to realize a much brighter X-ray at saturation, compared with the optical undulator under the same undulator strength and beam quality. In order to fill the high-power THz gap and realize the THz undulator, two superimposed laser pulses at normal incidence to the electron-beam moving direction form an equivalent high-field THz undulator by the frequency difference to realize the high-gain X-ray Free electron laser. The pulse front tilt of lateral fed lasers is used to realize the electron-laser synchronic interaction. By PIC simulation, a higher gain and a larger X-ray radiation power by the beat wave THz undulator could be realized, compared with the optical undulator for the same electron beam parameters.

Chang, Chao; Hei, DongWei; Pellegrin, Claudio; Tantawi, Sami

2013-12-01

295

X-ray quantitative analysis of coal by the Reference Intensity Method. Final report  

Microsoft Academic Search

Twenty-four coal samples representing the four major rank types were analyzed by the x-ray RIM methodology which includes mass absorption analysis by x-ray transmission and quantitative x-ray powder diffraction. Twenty-three separate mineral species were observed in the samples, many of which could be quantified in the whole coal analysis. Several mineral species at levels of 5 wt % or less

B. L. Davis; L. R. Johnson; T. Mebrahtu

1986-01-01

296

Industrial x-ray fluorescence analysis new applications and challenges for cryogenic detectors  

Microsoft Academic Search

Cryogenic, high-resolution X-ray detectors have potential applications in industrial X-ray fluorescence (XRF) analysis. We discuss various XRF analysis techniques currently used in the semiconductor industry, problems encountered due to limitations of current detectors and the potential benefits of using cryogenic detectors in these applications. We give examples of demonstration experiments, compare the performance of current conventional and cryogenic X-ray spectrometers

1997-01-01

297

Capillary optics for micro x-ray fluorescence analysis  

NASA Astrophysics Data System (ADS)

Practically achieved parameters of capillary optics are presented. A micro x-ray fluorescence (XRF) arrangement was realized by using a microfocus x-ray tube and a capillary optic. Several examples for application of micro XRF are given. It was shown that polycapillary lenses free of the ``halo effect'' well suited for micro XRF of heavy elements can be manufactured. Limits of opportunities for micro XRF applications and further development for micro XRF by using capillary optics are analyzed.

Bjeoumikhov, A.; Langhoff, N.; Bjeoumikhova, S.; Wedell, R.

2005-06-01

298

Capillary optics for micro x-ray fluorescence analysis  

SciTech Connect

Practically achieved parameters of capillary optics are presented. A micro x-ray fluorescence (XRF) arrangement was realized by using a microfocus x-ray tube and a capillary optic. Several examples for application of micro XRF are given. It was shown that polycapillary lenses free of the 'halo effect' well suited for micro XRF of heavy elements can be manufactured. Limits of opportunities for micro XRF applications and further development for micro XRF by using capillary optics are analyzed.

Bjeoumikhov, A.; Langhoff, N.; Bjeoumikhova, S.; Wedell, R. [IfG Institut fuer Geraetebau GmbH, Rudower Chaussee 29/31, 12489 Berlin (Germany); Bundesanstalt fuer Materialforschung und-pruefung, 12200 Berlin (Germany); IAP Institut fuer angewandte Photonik e. V., Rudower Chaussee 29/31, 12489 Berlin (Germany)

2005-06-15

299

The effect of turbulent density perturbations on solar flare electron transport and X-ray spectrum  

NASA Astrophysics Data System (ADS)

RHESSI solar flare hard X-ray observations sometimes cannot be adequately interpreted in terms of purely collisional electron transport. We instead present numerical simulations where we consider the energetic electron-beam interactions in the presence of low frequency den-sity perturbations. We demonstrate how the turbulent density perturbations affect the high frequency Langmuir waves and in turn, the flare accelerated electron distribution. The conse-quences of this self-consistent treatment are discussed for the observable X-ray spectrum.

Hannah, Iain; Kontar, Eduard

300

Unveiling Obscured AGN with X-ray Spectral Analysis  

NASA Astrophysics Data System (ADS)

The circumnuclear medium enshrouding AGN can now be thoroughly investigated in X-rays using physically motivated, self-consistent models that have recently become available. These advanced models allow reliable column densities (N_Hs) to be derived and can provide insight into the complex geometry of the X-ray reprocessor, constraining both the line-of-sight and global column densities. We fit the X-ray spectra of 19 SDSS [OIII] 5007 Angstrom selected type 2 AGN with these models. Though our sources represent an X-ray bright subset of the parent [OIII]-selected type 2 AGN samples, most are heavily obscured (N_H > 10^23 cm^-2) to Compton-Thick (N_H > 1.25 x 10^24 cm^-2). Four objects have different global and line-of-sight column densities. We correct the X-ray emission for absorption, calculating the intrinsic X-ray luminosity, and find that the mean Lx/L_[OIII] ratio for this sample is nearly equivalent to that of the average value for Seyfert 1 (i.e., unabsorbed) AGN.

LaMassa, Stephanie M.; Yaqoob, Tahir; Ptak, Andrew; Jia, Jianjun; Heckman, Timothy M.; Gandhi, Poshak; Urry, C. Megan

2014-08-01

301

Crystallization and preliminary X-ray crystallographic analysis of importin-? from Neurospora crassa.  

PubMed

Importin-? recognizes cargo proteins that contain classical nuclear localization sequences (NLS) and, in complex with importin-?, is able to translocate nuclear proteins through the nuclear pore complex. The filamentous fungus Neurospora crassa is a well studied organism that has been widely used as a model organism for fundamental aspects of eukaryotic biology, and is important for understanding the specific mechanisms of protein transport to the cell nucleus. In this work, the crystallization and preliminary X-ray diffraction analysis of importin-? from N. crassa (IMP?-Nc) complexed with a classical NLS peptide (SV40 NLS) are reported. IMP?-Nc-SV40 NLS crystals diffracted X-rays to 2.0?Å resolution and the structure was solved by molecular-replacement techniques, leading to a monomeric structure. The observation of the electron-density map indicated the presence of SV40 NLSs interacting at both the minor and major NLS-binding sites of the protein. PMID:24699749

Bernardes, Natalia E; Takeda, Agnes A S; Freitas, Fernanda Z; Bertolini, Maria Célia; Fontes, Marcos R M

2014-04-01

302

Electron density characterization by use of a broadband x-ray-compatible wave-front sensor  

NASA Astrophysics Data System (ADS)

The use of a Hartmann wave-front sensor to accurately measure the line-integrated electron density gradients formed in laser-produced and z-pinch plasma experiments is examined. This wave-front sensor may be used with a soft-x-ray laser as well as with incoherent line emission at multikilovolt x-ray energies. This diagnostic is significantly easier to use than interferometery and moiré deflectometry, both of which have been demonstrated with soft-x-ray lasers. This scheme is experimentally demonstrated in the visible region by use of a Shack-Hartmann wave-front sensor and a liquid-crystal spatial light modulator to simulate a phase profile that could occur when an x-ray probe passes through a plasma. The merits of using a Hartmann sensor include a wide dynamic range, broadband or low-coherence-length light capability, high x-ray efficiency, two-dimensional gradient determination, multiplexing capability, and experimental simplicity. Hartmann sensors could also be utilized for wavelength testing of extreme-ultraviolet lithography components and x-ray phase imaging of biological specimens.

Baker, K. L.; Brase, J.; Kartz, M.; Olivier, S. S.; Sawvel, B.; Tucker, J.

2003-02-01

303

Energy-dispersive X-ray emission spectroscopy using an X-ray free-electron laser in a shot-by-shot mode.  

PubMed

The ultrabright femtosecond X-ray pulses provided by X-ray free-electron lasers open capabilities for studying the structure and dynamics of a wide variety of systems beyond what is possible with synchrotron sources. Recently, this "probe-before-destroy" approach has been demonstrated for atomic structure determination by serial X-ray diffraction of microcrystals. There has been the question whether a similar approach can be extended to probe the local electronic structure by X-ray spectroscopy. To address this, we have carried out femtosecond X-ray emission spectroscopy (XES) at the Linac Coherent Light Source using redox-active Mn complexes. XES probes the charge and spin states as well as the ligand environment, critical for understanding the functional role of redox-active metal sites. K?(1,3) XES spectra of Mn(II) and Mn(2)(III,IV) complexes at room temperature were collected using a wavelength dispersive spectrometer and femtosecond X-ray pulses with an individual dose of up to >100 MGy. The spectra were found in agreement with undamaged spectra collected at low dose using synchrotron radiation. Our results demonstrate that the intact electronic structure of redox active transition metal compounds in different oxidation states can be characterized with this shot-by-shot method. This opens the door for studying the chemical dynamics of metal catalytic sites by following reactions under functional conditions. The technique can be combined with X-ray diffraction to simultaneously obtain the geometric structure of the overall protein and the local chemistry of active metal sites and is expected to prove valuable for understanding the mechanism of important metalloproteins, such as photosystem II. PMID:23129631

Alonso-Mori, Roberto; Kern, Jan; Gildea, Richard J; Sokaras, Dimosthenis; Weng, Tsu-Chien; Lassalle-Kaiser, Benedikt; Tran, Rosalie; Hattne, Johan; Laksmono, Hartawan; Hellmich, Julia; Glöckner, Carina; Echols, Nathaniel; Sierra, Raymond G; Schafer, Donald W; Sellberg, Jonas; Kenney, Christopher; Herbst, Ryan; Pines, Jack; Hart, Philip; Herrmann, Sven; Grosse-Kunstleve, Ralf W; Latimer, Matthew J; Fry, Alan R; Messerschmidt, Marc M; Miahnahri, Alan; Seibert, M Marvin; Zwart, Petrus H; White, William E; Adams, Paul D; Bogan, Michael J; Boutet, Sébastien; Williams, Garth J; Zouni, Athina; Messinger, Johannes; Glatzel, Pieter; Sauter, Nicholas K; Yachandra, Vittal K; Yano, Junko; Bergmann, Uwe

2012-11-20

304

Energy-dispersive X-ray emission spectroscopy using an X-ray free-electron laser in a shot-by-shot mode  

PubMed Central

The ultrabright femtosecond X-ray pulses provided by X-ray free-electron lasers open capabilities for studying the structure and dynamics of a wide variety of systems beyond what is possible with synchrotron sources. Recently, this “probe-before-destroy” approach has been demonstrated for atomic structure determination by serial X-ray diffraction of microcrystals. There has been the question whether a similar approach can be extended to probe the local electronic structure by X-ray spectroscopy. To address this, we have carried out femtosecond X-ray emission spectroscopy (XES) at the Linac Coherent Light Source using redox-active Mn complexes. XES probes the charge and spin states as well as the ligand environment, critical for understanding the functional role of redox-active metal sites. K?1,3 XES spectra of MnII and Mn2III,IV complexes at room temperature were collected using a wavelength dispersive spectrometer and femtosecond X-ray pulses with an individual dose of up to >100 MGy. The spectra were found in agreement with undamaged spectra collected at low dose using synchrotron radiation. Our results demonstrate that the intact electronic structure of redox active transition metal compounds in different oxidation states can be characterized with this shot-by-shot method. This opens the door for studying the chemical dynamics of metal catalytic sites by following reactions under functional conditions. The technique can be combined with X-ray diffraction to simultaneously obtain the geometric structure of the overall protein and the local chemistry of active metal sites and is expected to prove valuable for understanding the mechanism of important metalloproteins, such as photosystem II.

Alonso-Mori, Roberto; Kern, Jan; Gildea, Richard J.; Sokaras, Dimosthenis; Weng, Tsu-Chien; Lassalle-Kaiser, Benedikt; Tran, Rosalie; Hattne, Johan; Laksmono, Hartawan; Hellmich, Julia; Glockner, Carina; Echols, Nathaniel; Sierra, Raymond G.; Schafer, Donald W.; Sellberg, Jonas; Kenney, Christopher; Herbst, Ryan; Pines, Jack; Hart, Philip; Herrmann, Sven; Grosse-Kunstleve, Ralf W.; Latimer, Matthew J.; Fry, Alan R.; Messerschmidt, Marc M.; Miahnahri, Alan; Seibert, M. Marvin; Zwart, Petrus H.; White, William E.; Adams, Paul D.; Bogan, Michael J.; Boutet, Sebastien; Williams, Garth J.; Zouni, Athina; Messinger, Johannes; Glatzel, Pieter; Sauter, Nicholas K.; Yachandra, Vittal K.; Yano, Junko; Bergmann, Uwe

2012-01-01

305

High-Performance X-ray Detection in a New Analytical Electron Microscope  

NASA Technical Reports Server (NTRS)

X-ray detection by energy-dispersive spectrometry in the analytical electron microscope (AEM) is often limited by low collected X-ray intensity (P), modest peak-to-background (P/B) ratios, and limitations on total counting time (tau) due to specimen drift and contamination. A new AFM has been designed with maximization of P. P/B, and tau as the primary considerations. Maximization of P has been accomplished by employing a field-emission electron gun, X-ray detectors with high collection angles, high-speed beam blanking to allow only one photon into the detector at a time, and simultaneous collection from two detectors. P/B has been maximized by reducing extraneous background signals generated at the specimen holder, the polepieces and the detector collimator. The maximum practical tau has been increased by reducing specimen contamination and employing electronic drift correction. Performance improvments have been measured using the NIST standard Cr thin film. The 0-3 steradian solid angle of X-ray collection is the highest value available. The beam blanking scheme for X-ray detection provides 3-4 times greater throughput of X-rays at high count rates into a recorded spectrum than normal systems employing pulse-pileup rejection circuits. Simultaneous X-ray collection from two detectors allows the highest X-ray intensity yet recorded to be collected from the NIST Cr thin film. The measured P/B of 6300 is the highest level recorded for an AEM. In addition to collected X-ray intensity (cps/nA) and P/B measured on the standard Cr film, the product of these can be used as a figure-of-merit to evaluate instruments. Estimated minimum mass fraction (MMF) for Cr measured on the standard NIST Cr thin film is also proposed as a figure-of-merit for comparing X-ray detection in AEMs. Determinations here of the MMF of Cr detectable show at least a threefold improvement over previous instruments.

Lyman, C. E.; Goldstein, J. I.; Williams, D. B.; Ackland, D. W.; vonHarrach, S.; Nicholls, A. W.; Statham, P. J.

1994-01-01

306

Project Title: Radiochemical Analysis by High Sensitivity Dual-Optic Micro X-ray Fluorescence  

SciTech Connect

A novel dual-optic micro X-ray fluorescence instrument will be developed to do radiochemical analysis of high-level radioactive wastes at DOE sites such as Savannah River Site and Hanford. This concept incorporates new X-ray optical elements such as monolithic polycapillaries, which focus X-rays. The polycapillary optic can be used to focus X-rays emitted by the X-ray tube thereby increasing the X-ray flux on the sample over 1000 times. The polycapillary optic will also be used to collect the X-rays from the excitation site. This will effectively screen the radiation background from the radioactive species in the specimen. This dual-optic approach significantly reduces the background and increases the analyte signal thereby increasing the sensitivity of the analysis. This dual-capillary design is essentially a confocal (having the same foci) design, i.e. the detected X-rays are only emitted from the overlap of the two focal spots. This increases spatial resolution and reduce s background. The integration of the X-ray optics increases the signal-to-noise and thereby increases the sensitivity of the analysis for low-level analytes. This work will address a key need for radiochemical analysis of high-level waste using a non-destructive, multi-element, and rapid method in a radiation environment. There is significant potential that this instrumentation could be capable of on-line analysis for process waste stream characterization at DOE sites.

Havrilla, George J.; Gao, Ning

2003-06-01

307

Radiochemical Analysis by High Sensitivity Dual-Optic Micro X-ray Fluorescence  

SciTech Connect

A novel dual-optic micro X-ray fluorescence instrument will be developed to do radiochemical analysis of high-level radioactive wastes at DOE sites such as Savannah River Site and Hanford. This concept incorporates new X-ray optical elements such as monolithic polycapillaries, which focus X-rays. The polycapillary optic can be used to focus X-rays emitted by the X-ray tube thereby increasing the X-ray flux on the sample over 1000 times. The polycapillary optic will also be used to collect the X-rays from the excitation site. This will effectively screen the radiation background from the radioactive species in the specimen. This dual-optic approach significantly reduces the background and increases the analyte signal thereby increasing the sensitivity of the analysis. This dual-capillary design is essentially a confocal (having the same foci) design, i.e. the detected X-rays are only emitted from the overlap of the two focal spots. This increases spatial resolution and reduces background. The integration of the X-ray optics increases the signal-to-noise and thereby increases the sensitivity of the analysis for low-level analytes. This work will address a key need for radiochemical analysis of high-level waste using a non-destructive, multi-element, and rapid method in a radiation environment. There is significant potential that this instrumentation could be capable of on-line analysis for process waste stream characterization at DOE sites.

Havrilla, George J.; Gao, Ning

2004-06-01

308

Exploring the wavefront of hard X-ray free-electron laser radiation.  

PubMed

The high photon flux and femtosecond pulse duration of hard X-ray free-electron lasers have spurred a large variety of novel and fascinating experiments in physical, chemical and biological sciences. Many of these experiments depend fundamentally on a clean, well-defined wavefront. Here we explore the wavefront properties of hard X-ray free-electron laser radiation by means of a grating interferometer, from which we obtain shot-to-shot wavefront information with an excellent angular sensitivity on the order of ten nanoradian. The wavefront distortions introduced by optical elements are observed in-situ and under operational conditions. The source-point position and fluctuations are measured with unprecedented accuracy in longitudinal and lateral direction, both during nominal operation and as the X-ray free-electron laser is driven into saturation. PMID:22781760

Rutishauser, Simon; Samoylova, Liubov; Krzywinski, Jacek; Bunk, Oliver; Grünert, Jan; Sinn, Harald; Cammarata, Marco; Fritz, David M; David, Christian

2012-01-01

309

Efficiency calibration of an HPGe X-ray detector for quantitative PIXE analysis  

NASA Astrophysics Data System (ADS)

Particle Induced X-ray Emission (PIXE) is an analytical technique, which provides reliably and accurately quantitative results without the need of standards when the efficiency of the X-ray detection system is calibrated. The ion beam microprobe of the Ion Beam Modification and Analysis Laboratory at the University of North Texas is equipped with a 100 mm2 high purity germanium X-ray detector (Canberra GUL0110 Ultra-LEGe). In order to calibrate the efficiency of the detector for standard less PIXE analysis we have measured the X-ray yield of a set of commercially available X-ray fluorescence standards. The set contained elements from low atomic number Z = 11 (sodium) to higher atomic numbers to cover the X-ray energy region from 1.25 keV to about 20 keV where the detector is most efficient. The effective charge was obtained from the proton backscattering yield of a calibrated particle detector.

Mulware, Stephen J.; Baxley, Jacob D.; Rout, Bibhudutta; Reinert, Tilo

2014-08-01

310

X-ray spectroscopy of highly-ionized atoms in an electron beam ion trap (EBIT)  

SciTech Connect

An Electron Beam Ion Trap at Lawrence Livermore National Laboratory is being used to produce and trap very-highly-charged-ions (q /le/ 70+) for x-ray spectroscopy measurements. Recent measurements of dielectronic recombination, electron impact excitation and transition energies are presented. 15 refs., 12 figs., 1 tab.

Marrs, R.E.; Bennett, C.; Chen, M.H.; Cowan, T.; Dietrich, D.; Henderson, J.R.; Knapp, D.A.; Levine, M.A.; Schneider, M.B.; Scofield, J.H.

1988-01-01

311

X-ray spectra from the Cornell Electron-Beam Ion Source (CEBIS I)  

SciTech Connect

Radiation emitted from the Cornell electron beam ion source (CEBIS I) has been surveyed with a Si(Li) x-ray detector. These spectra can be used to estimate backgrounds from electron bremsstrahlung and to evaluate the feasibility of atomic physics experiments using the CEBIS I source in this configuration. 1 ref., 2 figs.

Johnson, B.M.; Jones, K.W.; Kostroun, V.O.; Ghanbari, E.; Janson, S.W.

1985-01-01

312

Design optimization for an X-ray free electron laser driven by SLAC linac  

Microsoft Academic Search

I present a design study for an X-ray Free Electron Laser (FEL) driven by the SLAC linac. The study assumes the FEL is based on Self-Amplified Spontaneous Emission (SASE) and lasing is achieved in a single pass of a high current, high brightness electron beam through a long wiggler. Following a brief review of the fundamentals of SASE, I provide

Ming Xie

1995-01-01

313

The Space-Distribution of the Photo-Electrons Ejected by X-Rays  

Microsoft Academic Search

None of the theories which have heretofore been proposed to account for the apparent emission of x-ray electrons from the atom over a wide range of angles instead of in one definite direction is entirely satisfactory. Since the scattering of the electrons which takes place in neighboring atoms has not been completely eliminated in any of the experimental work, the

E. C. Watson

1928-01-01

314

Comment on 'Bremsstrahlung X rays from Jovian auroral electrons' by D.D. Barbosa  

NASA Astrophysics Data System (ADS)

Calculations are presented showing that the suggestion of Barbosa (1990) that electron bremsstrahlung is the most likely source of the auroral X-ray emission that has been observed at Jupiter is flawed. This is because the Barbosa's hypothesis ignores the constraint that the primary electron distribution parameters place on the parameters for the secondary electron distribution. As a result, the secondary electron fluxes postulated by Barbosa are over 3 orders of magnitude greater than the theory of auroral electrons permits.

Waite, J. H., Jr.

1991-11-01

315

Study of runaway electrons using dosimetry of hard x-ray radiations in Damavand tokamak.  

PubMed

In this work several studies have been conducted on hard x-ray emissions of Damavand tokamak based on radiation dosimetry using the Thermoluminescence method. The goal was to understand interactions of runaway electrons with plasma particles, vessel wall, and plasma facing components. Total of 354 GR-200 (LiF:Mg,Cu,P) thermoluminescence dosimeter (TLD) crystals have been placed on 118 points--three TLDs per point--to map hard x-ray radiation doses on the exterior of the vacuum vessel. Results show two distinctive levels of x-ray radiations doses on the exterior of the vessel. The low-dose area on which measured dose is about 0.5 mSv/shot. In the low-dose area there is no particular component inside the vessel. On the contrary, on high-dose area of the vessel, x-ray radiations dose exceeds 30 mSv/shot. The high-dose area coincides with the position of limiters, magnetic probe ducts, and vacuum vessel intersections. Among the high-dose areas, the highest level of dose is measured in the position of the limiter, which could be due to its direct contact with the plasma column and with runaway electrons. Direct collisions of runaway electrons with the vessel wall and plasma facing components make a major contribution for production of hard x-ray photons in Damavand tokamak. PMID:24880371

Rasouli, C; Pourshahab, B; Hosseini Pooya, S M; Orouji, T; Rasouli, H

2014-05-01

316

Study of runaway electrons using dosimetry of hard x-ray radiations in Damavand tokamak  

NASA Astrophysics Data System (ADS)

In this work several studies have been conducted on hard x-ray emissions of Damavand tokamak based on radiation dosimetry using the Thermoluminescence method. The goal was to understand interactions of runaway electrons with plasma particles, vessel wall, and plasma facing components. Total of 354 GR-200 (LiF:Mg,Cu,P) thermoluminescence dosimeter (TLD) crystals have been placed on 118 points - three TLDs per point - to map hard x-ray radiation doses on the exterior of the vacuum vessel. Results show two distinctive levels of x-ray radiations doses on the exterior of the vessel. The low-dose area on which measured dose is about 0.5 mSv/shot. In the low-dose area there is no particular component inside the vessel. On the contrary, on high-dose area of the vessel, x-ray radiations dose exceeds 30 mSv/shot. The high-dose area coincides with the position of limiters, magnetic probe ducts, and vacuum vessel intersections. Among the high-dose areas, the highest level of dose is measured in the position of the limiter, which could be due to its direct contact with the plasma column and with runaway electrons. Direct collisions of runaway electrons with the vessel wall and plasma facing components make a major contribution for production of hard x-ray photons in Damavand tokamak.

Rasouli, C.; Pourshahab, B.; Hosseini Pooya, S. M.; Orouji, T.; Rasouli, H.

2014-05-01

317

Micro-column Scanning Electron Microscope and X-ray Spectrometer (MSEMS) for Planetary Exploration  

NASA Astrophysics Data System (ADS)

Scanning Electron Microscopy combined with electron-induced X-ray Fluorescence Spectroscopy (SEM-EDX) is one of the most powerful techniques for characterizing sub-µm surface morphology and composition. In terrestrial laboratories, SEM-EDX is used to elucidate natural processes such as low-temperature diagenesis, thermal or pressure induced metamorphism, volcanism/magmatism, atmosphere/crust interaction and biological activity. Such information would be highly useful for investigating the natural history of the terrestrial planets, satellites and primitive bodies, providing morphological and elemental information that is 2 orders of magnitude higher in resolution than optical techniques. Below we describe the development of a Micro-column Scanning Electron Microscope and X-ray Spectrometer (MSEMS) for flight. The enabling technology of the MSEMS is a carbon nanotube field emission (CNTFE) electron source that is integrated with micro-electro-mechanical-systems (MEMS) - based electron gun and electron optical structures. A hallmark of CNTFE electron sources is their low chromatic aberration, which reduces the need for high accelerating voltages to obtain small spot size. The CNTFE also offers exceptional brightness and nanometer source size, eliminating the need for condenser lenses, making simple electrostatic focusing optics possible. Moreover, the CNT field emission gun (CFEG) at low operating voltage dissipates 103 less power than thermally-assisted Schottky emitters. A key feature of the MSEMS design is the lack of scanning coils. Rather, a piezoelectric sample stage capable of sub-nanometer resolution scans the sample past the fixed crossover of the MSEMS electron beam. We will describe a MEMS-based templating technique for fabricating mechanically and electrically stable miniature CFEGs. Using existing silicon (Si) technology, we fabricated highly controlled and precise MEMS structures for both the CNT cathode and focusing optics for the micro-column. The reproducibility of anisotropic wet etching enables precise alignment of the CNT tip with the electron extracting first anode in a gun configuration by using an interlocking templating technique. The CFEG can be fully integrated with a MEMS-based microcolumn. Extensive electron trajectory analysis using Lorentz 2D/3D software demonstrates that 10-nm imaging resolution at 5 keV is achievable with a 10-mm working distance from a column measuring just 16 mm in length. We will present the design of the microcolumn as well as the MEMS fabrication process. We have also tested a piezoelectric scanning stage inside a laboratory SEM with a fixed electron beam. Additional, we implemented our own LabVIEW software interface for controlling the stage and for enabling communication with the secondary electron detector for image formation. SEM micrographs obtained employing this novel technique will be presented.

Ribaya, B.; Niemann, D.; Makarewicz, J.; Clevenson, H.; McKenzie, C.; Nguyen, C.; Blake, D. F.

2009-12-01

318

A new film analysis method using polycapillary X-ray lens  

NASA Astrophysics Data System (ADS)

Grazing emission X-ray fluorescence (GE-XRF) is a development of XRF related to total reflection XRF. This paper proposed a GE-MXRF setup involved a polycapillary X-ray lens. Polycapillary lens is an effective optics to obtain ?m-size primary X-ray beam. Using this proposed setup, we applied it to the analysis of film samples, and the information of film thickness, composition and density can be acquired, which is very useful in semiconductor industry.

Yang, Jun; Ding, Xunliang; Liang, Changlin

2007-08-01

319

Determination of tungsten in ores by energy dispersive X-ray fluorescence analysis  

Microsoft Academic Search

The possible determination of tungsten in low grade ores from Northern India, Rajasthan State has been explored by energy dispersive X-ray fluorescence analysis \\/EDXRF\\/ technique using radioisotope based excitation of W L X-rays and high resolution Si\\/Li\\/ detector system. Finely powdered ore has been diluted with optimal quantity of cellulose and converted into pellets to make it suitable for X-ray

M. P. Chacharkar; M. D. Sathe; Madan Lal

1987-01-01

320

X-Ray Fluorescence Analysis of a Gold Ibex and other Artifacts from Akrotiri  

Microsoft Academic Search

The in-situ X-ray fluorescence analysis (XRF) of ancient artifacts from the excavation area of Akrotiri, Greece was performed using novel instrumentation composed of a portable silicon PIN thermoelectrically cooled X-ray detector, a miniature X-ray source, and portable data acquisition devices. The main objective of the analyses was to explore the potential of the XRF technique to provide answers to a

T. Pantazis; A. G. Karydas; A. Vlachopoulos; P. Nomikos; M. Dinsmoree

321

Quantitative analysis of single aerosol particles using polycapillary X-ray optics  

Microsoft Academic Search

A laboratory micro X-ray fluorescence spectrometer based on polycapillary X-ray optics (PXRO) was used to carry out the quantitative X-ray fluorescence analysis of single aerosol particles with smaller size than that of focal spot of PXRO. The minimum detection limits measured with the thin-film reference standards were in the range from 13.3 to 0.7ngcm?2 when the operating current and voltage

Tianxi Sun; Zhiguo Liu; Yude Li; Guangfu Wang; Guanghua Zhu; Xunliang Ding; Qing Xu; Hui Liu; Ping Luo; Qiuli Pan; Xiaoyan Lin; Yuepeng Teng

2009-01-01

322

A new film analysis method using polycapillary X-ray lens  

Microsoft Academic Search

Grazing emission X-ray fluorescence (GE-XRF) is a development of XRF related to total reflection XRF. This paper proposed a GE-MXRF setup involved a polycapillary X-ray lens. Polycapillary lens is an effective optics to obtain ?m-size primary X-ray beam. Using this proposed setup, we applied it to the analysis of film samples, and the information of film thickness, composition and density

Jun Yang; Xunliang Ding; Changlin Liang

2007-01-01

323

Grazing exit micro X-ray fluorescence analysis of a hazardous metal attached to a plant leaf surface using an X-ray absorber method.  

PubMed

If human beings or animals repeatedly ingest plant leaves contaminated with minute quantities of hazardous metals (Pb, As, Hg, Cd, etc.), the metals will gradually accumulate in their bodies. When the quantities of the metals in the bodies reach toxic levels, they may cause serious symptoms of poisoning. Therefore, it is significant to detect and analyze the minute quantities of hazardous metals that attach to plant leaves in terms of epidemiology and disease prevention. We developed grazing exit micro X-ray fluorescence analysis (GE-micro-XRF), which was expected to analyze the localized surface of an aqueous plant leaf with a much faster and simpler sample treatment than with conventional analytical methods, to detect Pb attached to a surface of a leaf of Camellia hiemalis. A micro X-ray beam was produced by using a polycapillary X-ray lens. GE-v-XRF is a grazing exit X-ray analysis (GE-XA) method in which X-rays emitted from only the near-surface region of a specimen are selectively detected under a grazing exit angle condition (extremely low exit angle near 0 degrees). In any GE-XA method, X-rays emitted from inside the specimen must be absorbed inside the specimen and attenuated when X-rays pass through the specimen. However, we deduced that X-rays emitted from inside aqueous organic material such as a plant leaf are scarcely absorbed because X-ray absorption in any aqueous organic material is much smaller than that in most metallic and semiconductor materials, which was analyzed with GE-XA methods. Therefore, we have developed a novel GE-micro-XRF method in which a chip of a silicon wafer is placed between the analyzed leaf and an X-ray detector as an absorber of the X-rays emitted from inside the leaf. As a result of GE-XRF analysis of a leaf dipped in Pb standard solution using the X-ray absorber, we have for the first time selectively detected X-rays emitted from the near-surface region of an aqueous plant leaf. Therefore, we have detected X-rays emitted from Pb with much higher peak/background ratios (P/B ratios) as compared to those of conventional XRF analysis. In the analysis, we also found a difference in element distributions between the leaf surface and its interior. Therefore, we observed and analyzed a cross section of the leaf with a SEM-EDX to confirm the validity of this result. The result of the analysis of the cross section has been in excellent agreement with that of the XRF analysis. PMID:19402720

Awane, Tohru; Fukuoka, Shintaro; Nakamachi, Kazuo; Tsuji, Kouichi

2009-05-01

324

The identification of the pigments used to paint statues of Feixiange Cliff in China in late 19th century by micro-Raman spectroscopy and scanning electron microscopy\\/energy dispersive X-ray analysis  

Microsoft Academic Search

The application of micro-Raman spectroscopy (?-RS) and scanning electron microscopy (SEM)\\/energy dispersive X-ray spectrometer (EDS) to the research of pigments collected from Statues of Feixiange Cliff No. 67 and No. 69 niche of Tang Dynasty in China is reported. Five kinds of pigments were found in the experimental data, including black (carbon), white (gypsum+quartz), blue (lapis lazuli) and green (Paris

Pu-jun Jin; Wei Huang; Jianhua-Wang; Gang Zhao; Xiao-ling Wang

2010-01-01

325

Analysis of particles produced during airbag deployment by scanning electron microscopy with energy dispersive x-ray spectroscopy and their deposition on surrounding surfaces: a mid-research summary  

NASA Astrophysics Data System (ADS)

Airbags can be encountered in forensic work when investigating a car crash and are typically constructed with primerlike material to begin the deployment apparatus. The mechanisms of airbag deployment can produce particles ideal for scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDS) analysis. A recent study published by Berk studied airbags with vents and showed that it is possible for particles generated from the deployment of these airbags to deposit on surfaces in the vehicle as the airbags deflate.1 Another paper published by Berk reported particles similar in morphology and composition to primer gunshot residue (GSR) are produced by side impact airbags.2 This paper's aim will be to show mid-point results of a study still in progress in which non-vented airbags were analyzed to determine if they exhibited the same particle depositing features as their vented airbag counterparts. Further investigation in this study is being performed to find more airbags which produce primer gunshot residue-like particles containing lead, barium, and antimony from airbag deployment. To date, the study has resulted in (1) non-vented airbags exhibiting deposition of particles suitable for SEM/EDS analysis and (2) no gunshot residue-like particles being detected from the airbag residues studied thus far.

Wyatt, J. Matney

2011-05-01

326

Electron-optical recorder for pulse x-ray diagnostics of high-speed processes  

NASA Astrophysics Data System (ADS)

At research of high speed gas-dynamic processes x-ray image recording method is widely applied. The informativity of this method is defined by characteristics of the x-ray image formation system, which consists from x-ray or gamma- radiation source and a system of images recording. Application of developed in RFNC VNIIEF electron-optical recorders of the x-ray images has allowed to realize multi- frame recording of gas-dynamic processes and to expand methodical opportunities of x-ray imaging technique. The ways of technical realization of the high speed electron- optical recorders for single and multi-frame recorders for single and multi-frame recording are stated. Experimental results of check and the main characteristics of the electron-optical recorders are discussed. It is shown, that the sensitivity of such recorders can be changed in very wide range up to limiting, when each absorbed gamma-quantum is registered. At present in RFNC VNIIEF the electron- optical recorder `FIAR' is developed and widely applied. The result of four frames recording of plasma jet development on an output of plasma covering device also presented as an example of the recorder work. Prospects of development and perfection of characteristics of the electron-optical recorders and expansion of their application field are considered. An opportunity of creation of the x-ray image recorder with sensitive field above 4 square meters, enabling to receive the information on researched object in real time mode is shown. The design of such recorder permits fast adaptation for the requirements of gas-dynamic experiment.

Burtsev, Vasily V.; Elfimov, Sergey E.; Makarov, Yuri M.; Ryzhkov, Andrey V.

1997-05-01

327

TOPICAL REVIEW: Human soft tissue analysis using x-ray or gamma-ray techniques  

NASA Astrophysics Data System (ADS)

This topical review is intended to describe the x-ray techniques used for human soft tissue analysis. X-ray techniques have been applied to human soft tissue characterization and interesting results have been presented over the last few decades. The motivation behind such studies is to provide improved patient outcome by using the data obtained to better understand a disease process and improve diagnosis. An overview of theoretical background as well as a complete set of references is presented. For each study, a brief summary of the methodology and results is given. The x-ray techniques include x-ray diffraction, x-ray fluorescence, Compton scattering, Compton to coherent scattering ratio and attenuation measurements. The soft tissues that have been classified using x-rays or gamma rays include brain, breast, colon, fat, kidney, liver, lung, muscle, prostate, skin, thyroid and uterus.

Theodorakou, C.; Farquharson, M. J.

2008-06-01

328

Electron temperature measurements of x-ray laser plasmas  

SciTech Connect

We present results of recent experiments at the NOVA laser to measure the electron temperature of neon-like yttrium X-my laser plasmas. Trace amounts of aluminum were introduced into yttrium exploding-foil targets. Time resolved electron temperatures were determined by comparing the measured aluminum K-shell spectra with detailed quasi-steady state calculations and are compared to 2D LASNEX hydrodynamics simulations.

Young, B.K.F.; Osterheld, A.L.; Shepherd, R.L.; Shimkaveg, G.M.; Cerjan, C.J.; Goldstein, W.H.; Rosen, M.D.; Walling, R.S.; Stewart, R.E.

1992-08-06

329

Hard x-ray and hot electron environment in vacuum hohlraums at the National Ignition Facility  

SciTech Connect

Time resolved hard x-ray images (hv>9 keV) and time integrated hard x-ray spectra (hv=18-150 keV) from vacuum hohlraums irradiated with four 351 nm wavelength National Ignition Facility [J. A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Technol. 26, 755 (1994)] laser beams are presented as a function of hohlraum size, laser power, and duration. The hard x-ray images and spectra provide insight into the time evolution of the hohlraum plasma filling and the production of hot electrons. The fraction of laser energy detected as hot electrons (F{sub hot}) shows a correlation with laser intensity and with an empirical hohlraum plasma filling model. In addition, the significance of Au K-alpha emission and Au K-shell reabsorption observed in some of the bremsstrahlung dominated spectra is discussed.

McDonald, J.W.; Suter, L.J.; Landen, O.L.; Foster, J.M.; Celeste, J.R.; Holder, J.P.; Dewald, E.L.; Schneider, M.B.; Hinkel, D.E.; Kauffman, R.L.; Atherton, L.J.; Bonanno, R.E.; Dixit, S.N.; Eder, D.C.; Haynam, C.A.; Kalantar, D.H.; Koniges, A.E.; Lee, F.D.; MacGowan, B.J.; Manes, K.R. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States)] (and others)

2006-03-15

330

X-Ray Amplification from a Raman Free-Electron Laser  

NASA Astrophysics Data System (ADS)

We demonstrate that a mm-scale free-electron laser can operate in the x-ray range, in the interaction between a moderately relativistic electron bunch, and a transverse high intensity optical lattice. The corrugated light-induced ponderomotive potential acts simultaneously as a guide and as a low-frequency wiggler, triggering stimulated Raman scattering. The gain law in the small signal regime is derived in a fluid approach, and confirmed from particle-in-cell simulations. We describe the nature of bunching, and discuss the saturation properties. The resulting all-optical Raman x-ray laser opens perspectives for ultracompact coherent light sources up to the hard x-ray range.

Andriyash, I. A.; d'Humières, E.; Tikhonchuk, V. T.; Balcou, Ph.

2012-12-01

331

Catalyst analysis using synchrotron X-ray microscopy  

NASA Astrophysics Data System (ADS)

Synchrotron X-ray microscopy techniques have been used to characterize several different types of heterogeneous catalysts. Using a collimator to produce microbeams with a size of less than 10?m, maps of the elemental distributions based on detection of the fluorescent X-rays were made, and computed microtomography (CMT) techniques were applied to produce " phase/density contrast" maps. CMT techniques were also used to determine the distribution of a specific major element by making measurements above and below the K X-ray absorption edge. The measurements were made using bending magnet radiation and, in one case, radiation from a 4 T superconducting wiggler at the National Synchrotron Light Source. Examples of applications to the study of polyethylene polymerization particles, fluid catalytic cracking catalysts, and hydrotreating catalysts are given.

Jones, K. W.; Spanne, P.; Webb, S. W.; Conner, W. C.; Beyerlein, R. A.; Reagan, W. J.; Dautzenberg, F. M.

1991-05-01

332

THE X-RAY DETECTABILITY OF ELECTRON BEAMS ESCAPING FROM THE SUN  

SciTech Connect

We study the detectability and characterization of electron beams as they leave their acceleration site in the low corona toward interplanetary space through their nonthermal X-ray bremsstrahlung emission. We demonstrate that the largest interplanetary electron beams ({approx}>10{sup 35} electrons above 10 keV) can be detected in X-rays with current and future instrumentation, such as RHESSI or the X-Ray Telescope (XRT) onboard Hinode. We make a list of optimal observing conditions and beam characteristics. Amongst others, good imaging (as opposed to mere localization or detection in spatially integrated data) is required for proper characterization, putting the requirement on the number of escaping electrons (above 10 keV) to {approx}>3 x 10{sup 36} for RHESSI, {approx}>3 x 10{sup 35} for Hinode/XRT, and {approx}>10{sup 33} electrons for the FOXSI sounding rocket scheduled to fly in 2011. Moreover, we have found that simple modeling hints at the possibility that coronal soft X-ray jets could be the result of local heating by propagating electron beams.

Saint-Hilaire, Pascal; Krucker, Saem; Christe, Steven; Lin, Robert P. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)], E-mail: shilaire@ssl.berkeley.edu

2009-05-01

333

Femtosecond x-ray pulse characterization in free-electron lasers using a cross-correlation technique.  

PubMed

We report the first measurements of x-ray single-pulse duration and two-pulse separation at the Linac Coherent Light Source using a cross-correlation technique involving x rays and electrons. An emittance-spoiling foil is adopted as a very simple and effective method to control the output x-ray pulse. A minimum pulse duration of about 3 fs full width at half maximum has been measured together with a controllable pulse separation (delay) between two pulses. This technique provides critical temporal diagnostics for x-ray experiments such as x-ray pump-probe studies. PMID:23368472

Ding, Y; Decker, F-J; Emma, P; Feng, C; Field, C; Frisch, J; Huang, Z; Krzywinski, J; Loos, H; Welch, J; Wu, J; Zhou, F

2012-12-21

334

Femtosecond X-Ray Pulse Characterization in Free-Electron Lasers Using a Cross-Correlation Technique  

NASA Astrophysics Data System (ADS)

We report the first measurements of x-ray single-pulse duration and two-pulse separation at the Linac Coherent Light Source using a cross-correlation technique involving x rays and electrons. An emittance-spoiling foil is adopted as a very simple and effective method to control the output x-ray pulse. A minimum pulse duration of about 3 fs full width at half maximum has been measured together with a controllable pulse separation (delay) between two pulses. This technique provides critical temporal diagnostics for x-ray experiments such as x-ray pump-probe studies.

Ding, Y.; Decker, F.-J.; Emma, P.; Feng, C.; Field, C.; Frisch, J.; Huang, Z.; Krzywinski, J.; Loos, H.; Welch, J.; Wu, J.; Zhou, F.

2012-12-01

335

Phase distinction in semi-insulating polycrystalline silicon by pattern recognition of X-ray photoelectron spectroscopy/X-ray-induced Auger electron spectroscopy data  

NASA Astrophysics Data System (ADS)

X-ray photoelectron spectroscopy (XPS) and X-ray-induced Auger electron spectroscopy (XAES) supported with the lineshape analysis by the pattern recognition (PR) method and the fuzzy k-nearest neighbor rule ( kNN FR) were applied to study semiinsulating polycrystalline silicon layers (SIPOS). The aim of the present work was to obtain the qualitative and quantitative information about the surface region of as-received SIPOS layers. For the purpose of qualitative analysis the binding energies (BE), binding energy shifts (?BE), the half widths (FWHM) and the lineshapes of the Si 2p, O 1s and O KLL lines were analysed. The quantitative analysis was performed on the basis of the XPS using sensitivity factor method, multiline (ML) approach and the kNN FR. The performance of the kNN rule is possible after selecting the proper set of reference standard materials to which the rule refers during identification of an ambiguous chemical state. By selecting the reference samples supplying the information about the chemical state of Si, SiO x and SiO 2, the kNN rule allowed to distinguish qualitatively these three different phases in SIPOS samples. The particular application of the kNN FR makes possible the quantitative analysis by referring the fuzzy probability of classification for the given chemical state to the concentration of particular constituents in the investigated SIPOS. All the methods applied are consistent in revealing the quantitative results and show that SIPOS is a deeply non-homogeneous material, consisting of two phases: silicon and silicon oxide.

Lesiak, Beata; Zemek, Jozef; Jozwik, Adam

1998-09-01

336

Emission statistics of X-ray induced photoelectrons and its comparison with electron- and ion-induced electron emissions  

Microsoft Academic Search

The emission statistics of secondary electrons from a gold metal surface induced by monochromatic X-rays is studied by Monte Carlo simulations. The number distributions of emitted electrons n and their mean values ? are calculated systematically for incident photon energies from 1 to 100keV. The results are compared with recent experimental results measured at the SPring-8 X-ray beam facility (BL15XU).

K. Ohya; K. Inai; A. Nisawa; A. Itoh

2008-01-01

337

XSPEC12: Object-Oriented X-Ray Analysis  

NASA Astrophysics Data System (ADS)

XSPEC was designed to be a mission-independent general purpose X-ray data analysis program. In order for XSPEC to keep fulfilling this role well into the 21st Century we have re-implemented its code base in ANSI C++ using object oriented programming techniques. The abstract programming formulation used for XSPEC12 gives considerable advantages for the future. It will be possible to implement new data formats, table model formats, fitting and statistical techniques by loading ``add-in'' modules without the necessity of recompiling existing code. As the first examples, we have written modules that (a) read INTEGRAL/SPI data and responses and (b) implement the CERN/MINUIT optimization library. The new code can also solve problems with source confusion (multiple sources can be modeled and fit from a single spectrum). As for efficiency, the new code achieves similar performance in double precision arithmetic than XSPEC11 gives in single precision. For the cases of analysis with simple analytical models and large spectral arrays, and time series analyses (multiple spectra with the same response matrices) XSPEC12 should give a considerable speed advantage over previous versions. XSPEC12 will have a very similar, but enhanced, syntax over previous releases. It will continue to support user models in Fortran77, but will also support user models in C and C++. The I/O streams designed for XSPEC12 can support either a command line user interface or, in future, a GUI. Additionally, the plotting interface has been written to be independent of the plotting library: future releases will be able to implement newer user graphics packages. XSPEC12 should be available as an alpha release in the late Spring of 2003. We encourage readers to join the testing program that we will be announcing once the release date has been set.

Dorman, B.; Arnaud, K. A.; Gordon, Craig A.

2003-03-01

338

Food Irradiation Using Electron Beams and X-Rays  

Microsoft Academic Search

In this presentation we will discuss the technology of food irradiation using electron accelerators. Food irradiation has generally come to describe the use of ionizing radiation to decrease the population of, or prevent the growth of, undesirable biological organisms in food. The many beneficial applications include insect disinfestation, sprouting inhibition, delayed ripening, and the enhanced safety and sterilization of fresh

Bruce Miller

2003-01-01

339

Scanning Electron Microscopy and X-Ray Microanalysis  

Microsoft Academic Search

This outstanding volume has managed the nearly impossible task of combining the expertise of all six authors in a lucid and homogeneous style of writing. Subtitled `A Text for Biologists, Material Scientists and Geologists,' the book has evolved from a short course taught each summer at Lehigh University.The book provides a basic knowledge of (1) the electron optics for these

Arden L. Albee

1982-01-01

340

Elemental composition of strawberry plants inoculated with the plant growth-promoting bacterium Azospirillum brasilense REC3, assessed with scanning electron microscopy and energy dispersive X-ray analysis.  

PubMed

The elemental composition of strawberry plants (Fragaria ananassa cv. Macarena) inoculated with the plant growth-promoting bacterium Azospirillum brasilense REC3, and non-inoculated controls, was studied using scanning electron microscopy (SEM) and energy dispersive X-ray (EDS) analysis. This allowed simultaneous semi-quantification of different elements in a small, solid sample. Plants were inoculated and grown hydroponically in 50% or 100% Hoagland solution, corresponding to limited or optimum nutrient medium, respectively. Bacteria-inoculated plants increased the growth index 45% and 80% compared to controls when grown in 100% and 50% Hoagland solution, respectively. Thus, inoculation with A. brasilense REC3 in a nutrient-limited medium had the strongest effect in terms of increasing both shoot and root biomass and growth index, as already described for Azospirillum inoculated into nutrient-poor soils. SEM-EDS spectra and maps showed the elemental composition and relative distribution of nutrients in strawberry tissues. Leaves contained C, O, N, Na, P, K, Ca and Cu, while roots also had Si and Cl. The organic fraction (C, O and N) accounted for over 96.3% of the total chemical composition; of the mineral fraction, Na had higher accumulation in both leaves and roots. Azospirillum-inoculated and control plants had similar elemental quantities; however, in bacteria-inoculated roots, P was significantly increased (34.33%), which constitutes a major benefit for plant nutrition, while Cu content decreased (35.16%). PMID:24148195

Guerrero-Molina, M F; Lovaisa, N C; Salazar, S M; Díaz-Ricci, J C; Pedraza, R O

2014-07-01

341

Challenges to quantitative multivariate statistical analysis of atomic-resolution X-ray spectral.  

PubMed

A new aberration-corrected scanning transmission electron microscope equipped with an array of Si-drift energy-dispersive X-ray spectrometers has been utilized to acquire spectral image data at atomic resolution. The resulting noisy data were subjected to multivariate statistical analysis to noise filter, remove an unwanted and partially overlapping non-sample-specific X-ray signal, and extract the relevant correlated X-ray signals (e.g., channels with L and K lines). As an example, the Y?Ti?O? pyrochlore-structured oxide (assumed here to be ideal) was interrogated at the [011] projection. In addition to pure columns of Y and Ti, at this projection, there are also mixed 50-50 at. % Y-Ti columns. An attempt at atomic-resolution quantification is presented. The method proposed here is to subtract the non-column-specific signal from the elemental components and then quantify the data based upon an internally derived k-factor. However, a theoretical basis to predict this non-column-specific signal is needed to make this generally applicable. PMID:22849798

Kotula, Paul G; Klenov, Dmitri O; von Harrach, H Sebastian

2012-08-01

342

X-Ray Lines Close to Kll Auger Electron Energies from Iron, Cobalt, Nickel, and Copper Monocrystals  

NASA Astrophysics Data System (ADS)

By x-ray bombardment of metal monocrystals (Fe, Co, Ni, and Cu), x-rays of KLL radiative Auger electrons (KLL RAE) can be observed on the low energy side of the Kalpha lines. The energies of the x-rays of the KLL RAE of each monocrystal are the same for different lattice planes and when different kinds of x-ray tubes (Mo, W, and Cu) are used. Therefore, the peak energies detected within the KLL Auger electron energy limit are interpreted as KLL RAE x-rays. The measured intensity ratios of KLL/Kalpha are about 0.3%. Additionally, the ratio of I(Kbeta )/I(Kalpha) and I(Si escape peak)/I(Kalpha) are measured. All of these values agree well with theoretical values. The beam shapes of KLL RAE x-rays are studied by taking pictures of x-ray films. The intensity distribution for Ni and Cu are measured by changing the crystal angle with respect to the incident x-ray beam near the Bragg angles of KLL RAE x-rays. It is shown that the KLL RAE x-rays are very sharp and stimulated when the crystal is set at the Bragg angle of the KLL RAE with respect to the incident beam, which contains both the pumping radiation and Bremsstrahlung of the frequencies in the KLL RAE range in which the KLL x-rays stimulation is achieved.

Koo, Yeon Deog

1990-01-01

343

X-ray irradiation induced changes in electron transport in stabilized a-Se photoconductors  

SciTech Connect

We have examined the effect of high-dose x-ray irradiation on electron transport in stabilized amorphous selenium (a-Se) x-ray photoconductive films (of the type used in x-ray image detectors) by measuring the electron lifetime ?{sub e} through interrupted-field time-of-flight experiments. X-ray induced effects have been examined through two types of experiments. In recovery experiments, the a-Se was preirradiated with and without an applied field (5 V/?m) during irradiation with sufficient dose (typically ?20 Gy at 21 °C) to significantly reduce the electron lifetime by ?50%, and then the recovery of the lifetime was monitored as a function of time at three different temperatures, 10 °C, 21 °C, and 35 °C. The lifetime recovery kinetics was exponential with a relaxation time ?{sub r} that is thermally activated with an activation energy of 1.66 eV. ?{sub r} is a few hours at 21 °C and only a few minutes at 35 °C. In experiments examining the irradiation induced effects, the a-Se film was repeatedly exposed to x-ray radiation and the changes in the drift mobility and lifetime were monitored as a function of accumulated dose D. There was no observable change in the drift mobility. At 21 °C, the concentration of x-ray induced deep traps (or capture centers), N{sub d}, increases linearly with D (N{sub d} ? D) whereas at 35 °C, the recovery process prevents a linear increase in N{sub d} with D, and N{sub d} saturates. In all cases, even under high dose irradiation (?50 Gy), the lifetime was recoverable to its original equilibrium (pre-exposure) value within a few relaxation times.

Walornyj, M.; Kasap, S. O. [Department of Electrical and Computer Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9 (Canada)] [Department of Electrical and Computer Engineering, University of Saskatchewan, 57 Campus Drive, Saskatoon, Saskatchewan S7N 5A9 (Canada)

2013-12-07

344

Non-destructive surface characterization of float glass: X-ray reflectivity and grazing incidence X-ray fluorescence analysis  

Microsoft Academic Search

In the present study we have carried out non-destructive surface characterization of a float glass using total reflection X-ray fluorescence (TXRF) technique and X-ray reflectivity (XRR). The in-depth distribution of Sn and Fe impurities has been determined by TXRF where as X-ray optical properties such as r.m.s surface roughness, refractive index, etc., have been derived by XRR. The results obtained

M. K. Tiwari; M. H. Modi; G. S. Lodha; A. K. Sinha; K. J. S. Sawhney; R. V. Nandedkar

2005-01-01

345

Automated Chemical Analysis of Internally Mixed Aerosol Particles Using X-ray Spectromicroscopy at the Carbon K-Edge  

SciTech Connect

We have developed an automated data analysis method for atmospheric particles using scanning transmission X-ray microscopy coupled with near edge X-ray fine structure spectroscopy (STXM/NEXAFS). This method is applied to complex internally mixed submicrometer particles containing organic and inorganic material. Several algorithms were developed to exploit NEXAFS spectral features in the energy range from 278 to 320 eV for quantitative mapping of the spatial distribution of elemental carbon, organic carbon, potassium, and noncarbonaceous elements in particles of mixed composition. This energy range encompasses the carbon K-edge and potassium L2 and L3 edges. STXM/NEXAFS maps of different chemical components were complemented with a subsequent analysis using elemental maps obtained by scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM/EDX). We demonstrate the application of the automated mapping algorithms for data analysis and the statistical classification of particles.

Gilles, Mary K; Moffet, R.C.; Henn, T.; Laskin, A.

2011-01-20

346

Quantitative Mineralogical Analysis by X-ray diffraction.  

National Technical Information Service (NTIS)

Work was done in two phases on different combinations of soil-like crystalline materials that were mixed in the laboratory to develop a simple, rapid, and inexpensive method of doing quantitative mineralogical analyses, largely by X-ray diffraction (XRD)....

A. D. Buck

1972-01-01

347

X-Ray Diffraction Analysis of Lipstick and Gunpowder Samples  

Microsoft Academic Search

Using polycrystalline x-ray diffraction (XRD), we analyzed the chemical components of lipstick and gunpowder. Our three lipstick samples, although from the same manufacturer, were processed slightly differently. After obtaining an experimental pattern from the lipstick sample using a rotating Philips Expo diffractometer, we used the Philips HighScore computer program to compare our diffraction pattern with those from the International Center

Raheem Balogun; Samantha Berstler; Brian Kutsop

348

Femtosecond time-resolved X-ray absorption spectroscopy of liquid using a hard X-ray free electron laser in a dual-beam dispersive detection method.  

PubMed

We present femtosecond time-resolved X-ray absorption spectroscopy of aqueous solution using a hard x-ray free electron laser (SACLA) and a synchronized Ti:sapphire laser. The instrumental response time is 200 fs, and the repetition rate of measurement is 10 Hz. A cylindrical liquid beam 100 ?m in diameter of aqueous ammonium iron(III) oxalate solution is photoexcited at 400 nm, and the transient X-ray absorption spectra are measured in the K-edge region of iron, 7.10 - 7.26 keV, using a dual X-ray beam dispersive detection method. Each of the dual beams has the pulse energy of 1.4 ?J, and pump-induced absorbance change on the order of 10(-3) is successfully detected. The photoexcited iron complex exhibits a red shifted iron K-edge with the appearance time constant of 260 fs. The X-ray absorption difference spectra, with and without the pump pulses, are independent of time delay after 1.5 ps up to 100 ps, indicating that the photoexcited species is long-lived. PMID:24515070

Obara, Yuki; Katayama, Tetsuo; Ogi, Yoshihiro; Suzuki, Takayuki; Kurahashi, Naoya; Karashima, Shutaro; Chiba, Yuhei; Isokawa, Yusuke; Togashi, Tadashi; Inubushi, Yuichi; Yabashi, Makina; Suzuki, Toshinori; Misawa, Kazuhiko

2014-01-13

349

Electronic Structure in Thin Film Organic Semiconductors Studied using Soft X-ray Emission and Resonant Inelastic X-ray Scattering  

SciTech Connect

The electronic structure of thin films of the organic semiconductors copper and vanadyl (VO) phthalocyanine (Pc) has been measured using resonant soft X-ray emission spectroscopy and resonant inelastic X-ray scattering. For Cu-Pc we report the observation of two discrete states near E{sub F}. This differs from published photoemission results, but is in excellent agreement with density functional calculations. For VO-Pc, the vanadyl species is shown to be highly localized. Both dipole forbidden V 3d to V 3d*, and O 2p to V 3d* charge transfer transitions are observed, and explained in a local molecular orbital model.

Zhang,Y.; Downes, J.; Wang, S.; Learmonth, T.; Plucinski, L.; Matsuura, A.; McGuinness, C.; Glans, P.; Bernardis, S.; et al.

2006-01-01

350

Soft-x-ray harmonic comb from relativistic electron spikes.  

PubMed

We demonstrate a new high-order harmonic generation mechanism reaching the "water window" spectral region in experiments with multiterawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving ?J/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations. PMID:22540709

Pirozhkov, A S; Kando, M; Esirkepov, T Zh; Gallegos, P; Ahmed, H; Ragozin, E N; Faenov, A Ya; Pikuz, T A; Kawachi, T; Sagisaka, A; Koga, J K; Coury, M; Green, J; Foster, P; Brenner, C; Dromey, B; Symes, D R; Mori, M; Kawase, K; Kameshima, T; Fukuda, Y; Chen, L; Daito, I; Ogura, K; Hayashi, Y; Kotaki, H; Kiriyama, H; Okada, H; Nishimori, N; Imazono, T; Kondo, K; Kimura, T; Tajima, T; Daido, H; Rajeev, P; McKenna, P; Borghesi, M; Neely, D; Kato, Y; Bulanov, S V

2012-03-30

351

Soft-X-Ray Harmonic Comb from Relativistic Electron Spikes  

NASA Astrophysics Data System (ADS)

We demonstrate a new high-order harmonic generation mechanism reaching the “water window” spectral region in experiments with multiterawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving ?J/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations.

Pirozhkov, A. S.; Kando, M.; Esirkepov, T. Zh.; Gallegos, P.; Ahmed, H.; Ragozin, E. N.; Faenov, A. Ya.; Pikuz, T. A.; Kawachi, T.; Sagisaka, A.; Koga, J. K.; Coury, M.; Green, J.; Foster, P.; Brenner, C.; Dromey, B.; Symes, D. R.; Mori, M.; Kawase, K.; Kameshima, T.; Fukuda, Y.; Chen, L.; Daito, I.; Ogura, K.; Hayashi, Y.; Kotaki, H.; Kiriyama, H.; Okada, H.; Nishimori, N.; Imazono, T.; Kondo, K.; Kimura, T.; Tajima, T.; Daido, H.; Rajeev, P.; McKenna, P.; Borghesi, M.; Neely, D.; Kato, Y.; Bulanov, S. V.

2012-03-01

352

Design and measurement of a Cu L-edge x-ray filter for free electron laser pumped x-ray laser experiments  

SciTech Connect

An inner-shell photoionized x-ray laser pumped by the Linac Coherent Light Source (LCLS) free electron laser has been proposed recently. The measurement of the on-axis 849 eV Ne K{alpha} laser and protection of the x-ray spectrometer from damage require attenuation of the 1 keV LCLS beam. An Al/Cu foil combination is well suited, serving as a low energy bandpass filter below the Cu L-edge at 933 eV. A high resolution grating spectrometer is used to measure the transmission of a candidate filter with an intense laser-produced x-ray backlighter developed at the Lawrence Livermore National Laboratory Jupiter Laser Facility Janus. The methodology and discussion of the observed fine structure above the Cu L-edge will be presented.

Dunn, J.; London, R. A.; Rohringer, N. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Cone, K. V. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94550 (United States); Department of Applied Sciences, University of California, Davis, California 95616 (United States); Rocca, J. J. [NSF Center for Extreme Ultraviolet Science and Technology, Colorado State University, Fort Collins, Colorado 80523 (United States)

2010-10-15

353

Design and measurement of a Cu L-edge x-ray filter for free electron laser pumped x-ray laser experiments  

NASA Astrophysics Data System (ADS)

An inner-shell photoionized x-ray laser pumped by the Linac Coherent Light Source (LCLS) free electron laser has been proposed recently. The measurement of the on-axis 849 eV Ne K? laser and protection of the x-ray spectrometer from damage require attenuation of the 1 keV LCLS beam. An Al/Cu foil combination is well suited, serving as a low energy bandpass filter below the Cu L-edge at 933 eV. A high resolution grating spectrometer is used to measure the transmission of a candidate filter with an intense laser-produced x-ray backlighter developed at the Lawrence Livermore National Laboratory Jupiter Laser Facility Janus. The methodology and discussion of the observed fine structure above the Cu L-edge will be presented.

Dunn, J.; London, R. A.; Cone, K. V.; Rocca, J. J.; Rohringer, N.

2010-10-01

354

Serial femtosecond X-ray diffraction of 30S ribosomal subunit microcrystals in liquid suspension at ambient temperature using an X-ray free-electron laser  

PubMed Central

High-resolution ribosome structures determined by X-ray crystallography have provided important insights into the mechanism of translation. Such studies have thus far relied on large ribosome crystals kept at cryogenic temperatures to reduce radiation damage. Here, the application of serial femtosecond X-ray crystallography (SFX) using an X-ray free-electron laser (XFEL) to obtain diffraction data from ribosome microcrystals in liquid suspension at ambient temperature is described. 30S ribosomal subunit microcrystals diffracted to beyond 6?Å resolution, demonstrating the feasibility of using SFX for ribosome structural studies. The ability to collect diffraction data at near-physiological temperatures promises to provide fundamental insights into the structural dynamics of the ribosome and its functional complexes.

Demirci, Hasan; Sierra, Raymond G.; Laksmono, Hartawan; Shoeman, Robert L.; Botha, Sabine; Barends, Thomas R. M.; Nass, Karol; Schlichting, Ilme; Doak, R. Bruce; Gati, Cornelius; Williams, Garth J.; Boutet, Sebastien; Messerschmidt, Marc; Jogl, Gerwald; Dahlberg, Albert E.; Gregory, Steven T.; Bogan, Michael J.

2013-01-01

355

The Analysis of Physical Factor for X-Ray Phase Contrast Imaging  

Microsoft Academic Search

In this article, the basic principle of X-ray phase contrast imaging was firstly introduced. According to the microcosmic mechanism of interaction of the X-ray and the material, the relationship between atomic scattering factor and complex refractive index had been obtained. And then, the emphasis was given to the calculation and analysis of two important physical factors was related to the

Feng Sheng; Liu Song; Zhang Xuelong

2007-01-01

356

Chemical analysis of coal by energy dispersive x-ray fluorescence utilizing artificial standards  

Microsoft Academic Search

This chapter describes the use of x-ray fluorescence utilizing the powder method to make accurate determinations of the elemental composition of coal. It reports results of an analysis using an EG and G ORTEC 6110 Energy Dispersive X-ray Spectrometer. It explains that since coal standards are not particularly stable with time and some compositional ranges are not adequately covered, utilization

Wheeler

1982-01-01

357

X-ray Fluorescence Analysis of Powdered As x Se 100 – x Samples  

Microsoft Academic Search

A procedure was developed for the X-ray fluorescence determination of components in powdered samples of AsxSe100 – x, and its performance characteristics were determined. The relative standard deviation was 0.15% for the major components. The results of X-ray fluorescence analysis were in good agreement with data of atomic absorption spectroscopy.

N. I. Mashin; R. V. Lebedeva; A. N. Tumanova

2004-01-01

358

TOPICAL REVIEW: Human soft tissue analysis using x-ray or gamma-ray techniques  

Microsoft Academic Search

This topical review is intended to describe the x-ray techniques used for human soft tissue analysis. X-ray techniques have been applied to human soft tissue characterization and interesting results have been presented over the last few decades. The motivation behind such studies is to provide improved patient outcome by using the data obtained to better understand a disease process and

C. Theodorakou; M. J. Farquharson

2008-01-01

359

A Computer Program for Calculation of Calibration Curves for Quantitative X-Ray Diffraction Analysis.  

ERIC Educational Resources Information Center

Describes a FORTRAN IV program written to supplement a laboratory exercise dealing with quantitative x-ray diffraction analysis of mixtures of polycrystalline phases in an introductory course in x-ray diffraction. Gives an example of the use of the program and compares calculated and observed calibration data. (Author/GS)

Blanchard, Frank N.

1980-01-01

360

Implications of X-Ray Observations for Electron Acceleration and Propagation in Solar Flares  

NASA Technical Reports Server (NTRS)

High-energy X-rays and gamma-rays from solar flares were discovered just over fifty years ago. Since that time, the standard for the interpretation of spatially integrated flare X-ray spectra at energies above several tens of keV has been the collisional thick-target model. After the launch of the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) in early 2002, X-ray spectra and images have been of sufficient quality to allow a greater focus on the energetic electrons responsible for the X-ray emission, including their origin and their interactions with the flare plasma and magnetic field. The result has been new insights into the flaring process, as well as more quantitative models for both electron acceleration and propagation, and for the flare environment with which the electrons interact. In this article we review our current understanding of electron acceleration, energy loss, and propagation in flares. Implications of these new results for the collisional thick-target model, for general flare models, and for future flare studies are discussed.

Holman, G. D.; Aschwanden, M. J.; Aurass, H.; Battaglia, M.; Grigis, P. C.; Kontar, E. P.; Liu, W.; Saint-Hilaire, P.; Zharkova, V. V.

2011-01-01

361

Solar Electron Beams Detected in Hard X-Rays and Radio Waves  

Microsoft Academic Search

We present a statistical survey of electron beam signatures that are detected simultaneously at hard X-ray (HXR) and radio wavelengths during solar flares. For the identification of a simultaneous event we require a type III (normal-drifting or reverse-slope-drifting) radio burst that coincides (within ± 1 s) with a significant (>= 3 sigma HXR pulse of similar duration (>= 1 s).

Markus J. Aschwanden; Arnold O. Benz; Brian R. Dennis; Richard A. Schwartz

1995-01-01

362

Coherent X-ray radiation generated by a relativistic electron in an artificial periodic structure  

SciTech Connect

A theory of coherent X-ray radiation from a relativistic electron crossing an artificial periodic layered structure in the Laue scattering geometry is constructed. The expressions describing the spectral-angular radiation parameters are obtained. It is shown that the radiation yield in such a medium may substantially exceed the radiation yield in a crystal under analogous conditions.

Blazhevich, S. V. [Belgorod State University (Russian Federation); Kolosova, I. V.; Noskov, A. V., E-mail: noskovbupk@mail.ru [Belgorod University of Consumer Cooperatives (Russian Federation)

2012-04-15

363

SCANNING ELECTRON MICROSCOPY/X-RAY FLUORESCENCE CHARACTERIZATION OF POST-ABATEMENT DUST  

EPA Science Inventory

Scanning electron microscopy (SEM) and laboratory X-ray fluorescence (XRF) were used to characterize post-abatement dust collected with a HEPA filtered vacuum. hree size fractions of resuspended dust (0-30 pm, 2.5-15 pm, and ...

364

Nanofocusing of hard X-ray free electron laser pulses using diamond based Fresnel zone plates  

PubMed Central

A growing number of X-ray sources based on the free-electron laser (XFEL) principle are presently under construction or have recently started operation. The intense, ultrashort pulses of these sources will enable new insights in many different fields of science. A key problem is to provide x-ray optical elements capable of collecting the largest possible fraction of the radiation and to focus into the smallest possible focus. As a key step towards this goal, we demonstrate here the first nanofocusing of hard XFEL pulses. We developed diamond based Fresnel zone plates capable of withstanding the full beam of the world's most powerful x-ray laser. Using an imprint technique, we measured the focal spot size, which was limited to 320?nm FWHM by the spectral band width of the source. A peak power density in the focal spot of 4×1017?W/cm2 was obtained at 70 fs pulse length.

David, C.; Gorelick, S.; Rutishauser, S.; Krzywinski, J.; Vila-Comamala, J.; Guzenko, V. A.; Bunk, O.; Farm, E.; Ritala, M.; Cammarata, M.; Fritz, D. M.; Barrett, R.; Samoylova, L.; Grunert, J.; Sinn, H.

2011-01-01

365

Characteristics of a contract electron beam and bremsstrahlung (X-ray) irradiation facility of Radia industry  

NASA Astrophysics Data System (ADS)

A contract electron beam(EB) and bremsstrahlung(X-ray) facility with use of NHV 5 MeV, 30 mA Cock-Croft Walton machine is operational for EB since April 1991, and X-ray commercial irradiation was started in 1992 summer. The facility is consisted of the EB machine, bremsstrahlung target, chain and roller conveyor, and automatic turnover machine for dual sided irradiation. The operation of the system is fully controlled by LAN of personal computers for client's order, EB characteristics, beam current control proportional to the conveyor speed, turnover of product in processing mid point, and output of processing record to clients. The control and recording systems avoid human errors. This paper mainly discusses X-ray processing.

Takehisa, Masaaki; Saito, Toshio; Takahashi, Thoru; Sato, Yoshishige; Sato, Toshio

1993-07-01

366

Spectrometer for hard X-ray free-electron laser based on diffraction focusing.  

PubMed

X-ray free-electron lasers (XFELs) generate sequences of ultra-short spatially coherent pulses of X-ray radiation. A diffraction focusing spectrometer (DFS), which is able to measure the whole energy spectrum of the radiation of a single XFEL pulse with an energy resolution of ?E/E 2 × 10(-6), is proposed. This is much better than for most modern X-ray spectrometers. Such resolution allows one to resolve the fine spectral structure of the XFEL pulse. The effect of diffraction focusing occurs in a single-crystal plate due to dynamical scattering, and is similar to focusing in a Pendry lens made from a metamaterial with a negative refraction index. Such a spectrometer is easier to operate than those based on bent crystals. It is shown that the DFS can be used in a wide energy range from 5 keV to 20 keV. PMID:23412482

Kohn, V G; Gorobtsov, O Y; Vartanyants, I A

2013-03-01

367

Emerging opportunities in structural biology with X-ray free-electron lasers  

PubMed Central

X-ray free-electron lasers (X-FELs) produce X-ray pulses with extremely brilliant peak intensity and ultrashort pulse duration. It has been proposed that radiation damage can be “outrun” by using an ultra intense and short X-FEL pulse that passes a biological sample before the onset of significant radiation damage. The concept of “diffraction-before-destruction” has been demonstrated recently at the Linac Coherent Light Source, the first operational hard X-ray FEL, for protein nanocrystals and giant virus particles. The continuous diffraction patterns from single particles allow solving the classical “phase problem” by the oversampling method with iterative algorithms. If enough data are collected from many identical copies of a (biological) particle, its three-dimensional structure can be reconstructed. We review the current status and future prospects of serial femtosecond crystallography (SFX) and single-particle coherent diffraction imaging (CDI) with X-FELs.

Schlichting, Ilme; Miao, Jianwei

2012-01-01

368

Emerging opportunities in structural biology with X-ray free-electron lasers.  

PubMed

X-ray free-electron lasers (X-FELs) produce X-ray pulses with extremely brilliant peak intensity and ultrashort pulse duration. It has been proposed that radiation damage can be 'outrun' by using an ultra intense and short X-FEL pulse that passes a biological sample before the onset of significant radiation damage. The concept of 'diffraction-before-destruction' has been demonstrated recently at the Linac Coherent Light Source, the first operational hard X-ray FEL, for protein nanocrystals and giant virus particles. The continuous diffraction patterns from single particles allow solving the classical 'phase problem' by the oversampling method with iterative algorithms. If enough data are collected from many identical copies of a (biological) particle, its three-dimensional structure can be reconstructed. We review the current status and future prospects of serial femtosecond crystallography (SFX) and single-particle coherent diffraction imaging (CDI) with X-FELs. PMID:22922042

Schlichting, Ilme; Miao, Jianwei

2012-10-01

369

Investigations of large x-ray optics for free electron lasers  

NASA Astrophysics Data System (ADS)

A free electron laser (FEL) is being set up at DESY (Deutsches Elektronen Synchrotron, Hamburg, Germany). In the current XUV range of the FEL, total-reflection X-ray mirrors are needed for beam guidance, beam alignment, and monochromatisation. Such X-ray optics are used at a grazing incidence angle of about 2° thus a maximum length of about 500 mm is required. Due to the working range of the FEL (50 - 200 eV), carbon has been selected as a suitable material with an absorption edge at 284 eV. The amorphous carbon coatings were manufactured by magnetron sputtering in a special UHV system for large deposition at GKSS research centre (Geesthacht, Germany). The variation in film thickness over the whole length has been investigated by X-ray reflectometry (XRR). Good uniformity (better than 2 %) and low roughness (< 0.5 nm) have been observed.

Stormer, Michael; Liard-Cloup, Audrey; Felten, Frank; Jacobi, Sandra; Steeg, Barbara; Feldhaus, Josef; Bormann, Rudiger

2004-10-01

370

Generation of femtosecond X-ray pulses via Thomson scattering of terawatt IR laser pulses with relativistic electrons  

Microsoft Academic Search

Summary form only given. Generating femtosecond X-ray pulses via Thomson scattering of ultrashort laser pulses with relativistic electrons has a number of attractive advantages over other approaches. The duration of the generated X-rays is determined by the focal spot of the electron beam and the optical pulse duration. Thus generation of X-ray pulses of <100 fs duration is relatively straightforward.

Alan H. Chin; Robert E. Schoenlein; T. E. Clover; Charles V. Shank; Wim Leemans; Pavel Volfbeyn; Richa Govil; K.-J. Kim; Swapan Chattopadhyay

1996-01-01

371

Precise delineation characteristics for 1×X-ray mask using advanced electron beam mask writer EB-X3  

Microsoft Academic Search

A variable-shaped electron beam (e-beam) mask writer, EB-X3 was developed for 100 nm node 1×X-ray mask fabrication. It features a stable electron column of 100 kV and the address unit of 1 nm. This paper describes delineation characteristics of the EB-X3 on X-ray membrane mask. We have evaluated image placement (IP) accuracy and e-beam proximity effects on the X-ray membrane

S. Tsuboi; H. Watanabe; M. Ezaki; H. Aoyama; Y. Kikuchi; Y. Nakayama; S. Ohki; T. Watanabe; T. Morosawa; K. Saito; M. Oda; T. Matsuda

2000-01-01

372

[Methods of detector response function establishment in X-ray fluorescence spectra analysis].  

PubMed

During the measurement and analysis process of X-ray fluorescence spectra, it is very helpful to improve the analyze speed, accuracy and automaticity of X-ray fluorescence spectra analysis by establishing detector response function(DRF), which represents the shape of full energy peak and can provide former basic data for subsequent X-ray analysis technique. For the theory and model of semiconductor DRF in X-ray energy spectrum measurements, methods of three typical detector response function model establishment, key parameters of full energy peak standard deviation and Fano factor calculation, etc. are discussed, and meanwhile, the summarization and contrast of existing studies are shown in this paper. Finally, the suggestion for modeling methods of DRF in X-ray fluorescence spectra measurements is provided. PMID:23387190

Li, Zhe; Tuo, Xian-Guo; Yang, Jian-Bo; Liu, Ming-Zhe; Cheng, Yi; Wang, Lei; Zhou, Jian-Bin

2012-11-01

373

Electron Beam Production, Transport, and Final Focus for the PLEIADES Thomson X-ray Source  

NASA Astrophysics Data System (ADS)

The small interaction area required for Thomson x-ray sources necessitates the production of high brightness electron beams and the use of very strong final focus optics. We report on the details of the electron beam production, transport and final focus for the PLEIADES Thomson X-ray Source at Lawrence Livermore National Laboratory, including the S-band RF photocathode electron gun and 100 MeV S-Band accelerator, as well as the beam diagnostics and final focus optics. According to simulations, a beam emittance ranging from 2 to 5 mm-mrad is obtainable for bunch charges ranging from 0.5 to 1.0 nC, with an obtainable final focus spot size as low as 15 micro-meters rms for these beam parameters. The x-ray source is expected to produced pico-second xray pulses of brightness 1020 photons/0.1% bandwidth/mm^2/mrad^2 by colliding a 20 micro-meter, 0.5-1.0 nC, 0.5-5 ps electron bunch with a 100 fs, 300 mJ, 800 nm laser pulse. Measurements of the electron beam parameters and x-ray production will also be reported and compared to the theoretical expectations. In addition, the possibility of improving the electron beam focus and ultimate x-ray source brightness by implementing the use of stronger final focus optics will be discussed. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Brown, Winthrop J.; Anderson, Scott G.; Barty, Chris P.; Crane, John K.; Cross, Rick R.; Fittinghoff, Dave N.; Hartemann, Fred V.; Kuba, Jaroslav; Lesage, Greg P.; Slaughter, Dennis R.; Springer, Paul T.; Tremaine, Aaron M.; Gibson, David J.; Rosenzweig, James B.

2003-10-01

374

[Mineralization and structure of enamel (a study using scanning electron microscopy and X-ray micro-analysis of the lower incisor of the albino rat)].  

PubMed

In order to know the morphostructural changes that occurs in the enamel during the mineralization and to study the rod tridimensional orientation, the author has examined the literature concerning these subjects comparing it to the results of his researches realized by S.E.M. and Rx-microprobe-analysis. It has been demonstrated that three phases can be distinguished during the mineralization: "fibrillation phase", "rod density phase", "interrod density phase". The fibrillation phase begins in the middle of the ameloblastic secretion phase, ends 8 mm from the cervical ansa and is characterized by the unmasking of the matrix subunits and chemically by the disappearance of the sulphur. The rod density phase occurs in the area included between 8 and 14 mm from the cervical ansa, that is in the ameloblastic modulation phase, and is characterized by the aggregation of the intraprismatic subunits and by the calcium increase. The interrod density phase that occurs during the ameloblastic pigmentation phase, is characterized by the aggregation of the interprismatic subunits and by the presence of the iron in the most superficial enamel layers. The rod orientation in the space has been studied during the second phase of the mineralization suice the intraprismatic subunits join while the interprismatic ones remain in the fibrillation phase; besides the author has compared the results of these studies to the morphology of the external opening of the honeycomb pits. In such a way it has been demonstrated that the rod originates from the dentine-enamel junction forming a 60 degree angle that opens in the cuspidalmesial or cuspidal-lateral direction. In the outer enamel layer the rod loses its mesial or lateral inclination and bends further towards the cusp delimiting a 30 degree angle; finally it bends outward and as a sharpend that is ortogonal to the enamel external surface. It is eventually discussed how this model of rod reconstruction is fit to convert the tangential forces that develop during the mastication into compression forces. PMID:2694998

Anastasi, G

1989-01-01

375

X-ray diffraction and electron microscopic studies on selenium substituted indium intercalation compounds of tungsten disulphide  

Microsoft Academic Search

Selenium substituted indium intercalation compounds of tungsten disulphide, In1\\/3WS2?xSex (0?x?2) have been studied for microstructural characterization using X-ray line profile analysis to find out information about crystallite size, r.m.s. strain, dislocation density, variability of interlayer spacing, fraction of planes affected by such defects, stacking fault probability, crystallite size anisotropy etc. Scanning electron microscopic (SEM) and scanning tunneling microscopic (STM) studies

T. K. Mandal; S. K. Srivastava; B. K. Samantaray; B. K Mathur

1999-01-01

376

Characteristics of radiation safety for synchrotron radiation and X-ray free electron laser facilities.  

PubMed

Radiation safety problems are discussed for typical electron accelerators, synchrotron radiation (SR) facilities and X-ray free electron laser (XFEL) facilities. The radiation sources at the beamline of the facilities are SR, including XFEL, gas bremsstrahlung and high-energy gamma ray and photo-neutrons due to electron beam loss. The radiation safety problems for each source are compared by using 8 GeV class SR and XFEL facilities as an example. PMID:21493599

Asano, Yoshihiro

2011-07-01

377

Hard X-Ray Emission of X-Ray Bursters  

NASA Technical Reports Server (NTRS)

The primary goal of this proposal was to perform an accurate measurement of the broadband x-ray spectrum of a neutron-star low-mass x-ray binary found in a hard x-ray state. This goal was accomplished using data obtained under another proposal, which has provided exciting new information on the hard x-ray emission of neutron-star low-mass x-ray binaries. In "BeppoSAX Observations of the Atoll X-Ray Binary 4U0614+091", we present our analysis of the spectrum of 4U0614+091 over the energy band from 0.3-150 keV. Our data confirm the presence of a hard x-ray tail that can be modeled as thermal Comptonization of low-energy photons on electrons having a very high temperature, greater than 220 keV, or as a non-thermal powerlaw. Such a very hard x-ray spectrum has not been previously seen from neutron-star low-mass x-ray binaries. We also detected a spectral feature that can be interpreted as reprocessing, via Compton reflection, of the direct emission by an optically-thick disk and found a correlation between the photon index of the power-law tail and the fraction of radiation reflected which is similar to the correlation found for black hole candidate x-ray binaries and Seyfert galaxies. A secondary goal was to measure the timing properties of the x-ray emission from neutronstar low-mass x-ray binaries in their low/hard states.

Kaaret, P.

1999-01-01

378

Investigation of electron trajectories of an x-ray tube in magnetic fields of MR scanners  

SciTech Connect

A hybrid x-ray/MR system combining an x-ray fluoroscopic system and an open-bore magnetic resonance (MR) system offers advantages from both powerful imaging modalities and thus can benefit numerous image-guided interventional procedures. In our hybrid system configurations, the x-ray tube and detector are placed in the MR magnet and therefore experience a strong magnetic field. The electron beam inside the x-ray tube can be deflected by a misaligned magnetic field, which may damage the tube. Understanding the deflection process is crucial to predicting the electron beam deflection and avoiding potential damage to the x-ray tube. For this purpose, the motion of an electron in combined electric (E) and magnetic (B) fields was analyzed theoretically to provide general solutions that can be applied to different geometries. For two specific cases, a slightly misaligned strong field and a perpendicular weak field, computer simulations were performed with a finite-element method program. In addition, experiments were conducted using an open MRI magnet and an inserted electromagnet to quantitatively verify the relationship between the deflections and the field misalignment. In a strong (B>>E/c; c: speed of light) and slightly misaligned magnetic field, the deflection in the plane of E and B caused by electrons following the magnetic field lines is the dominant component compared to the deflection in the ExB direction due to the drift of electrons. In a weak magnetic field (B{<=}E/c), the main deflection is in the ExB direction and is caused by the perpendicular component of the magnetic field.

Wen Zhifei; Fahrig, Rebecca; Conolly, Steven; Pelc, Norbert J. [Departments of Radiology and Physics, Stanford University, Stanford, California 94305 (United States); Departments of Radiology, Stanford University, Stanford, California 94305 (United States); Department of Bioengineering, University of California, Berkeley, California 94720 (United States); Departments of Radiology and Bioengineering, Stanford University, Stanford, California 94305 (United States)

2007-06-15

379

Hard X-ray Time-Resolved/Space-Resolved X-ray Absorption Fine Structure Analysis for Heterogeneous Metal Catalysts  

NASA Astrophysics Data System (ADS)

Our recent examples of time-resolved and space-resolved X-ray absorption fine structure (XAFS) for heterogeneous solid catalysts are highlighted. In-situ time-resolved XAFS analysis of heterogeneous catalysts has provided new pieces of information on the structures of real active species on heterogeneous catalyst surfaces and their dynamic structural changes under reaction conditions. The structural transformation and phase separation of Pt--Sn alloy particles on support surfaces and the structural kinetics and reaction mechanism of Pt/C and Pt3Co alloy/C cathode catalysts in polymer electrolyte fuel cells (PEFCs) were investigated by in-situ time-resolved XAFS. The recent development and example of space-resolved XAFS, which shows us microscopic structural information of practical catalyst particles, are also introduced.

Tada, Mizuki

2013-02-01

380

Monte Carlo Simulation of the Conversion X-Rays from the Electron Beam of PFMA-3  

SciTech Connect

PFMA-3, a dense Plasma Focus device, is being optimized as an X-ray generator. X-rays are obtained from the conversion of the electron beam emitted in the backward direction and driven to impinge on a 50 {mu}m brass foil. Monte Carlo simulations of the X-ray emission have been conducted with MCNPX. The electron spectrum had been determined experimentally and is used in the present work as input to the simulations. Dose to the brass foil has been determined both from simulations and from measurements with a thermographic camera, and the two results are found in excellent agreement, thus validating further the electron spectrum assumed as well as the simulation set-up. X-ray emission has been predicted both from bremsstrahlung and from characteristic lines. The spectrum has been found to be comprised of two components of which the one at higher energy, 30 divide 70 keV, is most useful for IORT applications. The results are necessary to estimate penetration in and dose to Standard Human Tissue.

Ceccolini, E.; Mostacci, D.; Sumini, M. [Montecuccolino Nuclear Engineering Laboratory, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); Rocchi, F. [Montecuccolino Nuclear Engineering Laboratory, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); UTFISSM-PRONOC, ENEA, via Martiri di Monte Sole 4, I-40129 Bologna (Italy); Tartari, A. [Department of Physics, University of Ferrara, Via Saragat 1, I-44122 Ferrara (Italy)

2011-12-13

381

Measurement of electron density in dual-energy x-ray CT with monochromatic x rays and evaluation of its accuracy  

SciTech Connect

Information on electron density is important for radiotherapy treatment planning in order to optimize the dose distribution in the target volume of a patient. At present, the electron density is derived from a computed tomography (CT) number measured in x-ray CT scanning; however, there are uncertainties due to the beam hardening effect and the method by which the electron density is converted from the CT number. In order to measure the electron density with an accuracy of {+-}1%, the authors have developed dual-energy x ray CT using monochromatic x rays. They experimentally proved that the measured linear attenuation coefficients were only a few percent lower than the theoretical ones, which led to an accuracy within 2% for the electron density. There were three factors causing inaccuracy in the linear attenuation coefficient and the electron density: the influence of scattered radiation, the nonlinearity in the detector response function, and a theoretical process to derive the electron density from the linear attenuation coefficients. The linear attenuation coefficients of water were experimentally proved to differ by 1%-2% from the theoretical one even when the scattering effect was negligible. The nonlinearity of the response function played an important role in correcting the difference in the linear attenuation coefficient. Furthermore, the theoretical process used for deriving the electron density from the linear attenuation coefficients introduces about 0.6% deviation from the theoretical value into the resultant electron density. This deviation occurs systematically so that it can be corrected. The authors measured the electron densities for seven samples equivalent to soft tissue in dual-energy x-ray CT, and finally obtained them with an accuracy of around {+-}1%.

Tsunoo, Takanori; Torikoshi, Masami; Ohno, Yumiko; Uesugi, Kentaro; Yagi, Naoto [National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan); Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

2008-11-15

382

Project Title: Radiochemical Analysis by High Sensitivity Dual-Optic Micro X-ray Fluorescence  

SciTech Connect

A novel dual-optic micro X-ray fluorescence instrument will be developed to do radiochemical analysis of high-level radioactive wastes at DOE sites such as Savannah River Site and Hanford. This concept incorporates new X-ray optical elements such as monolithic polycapillaries and double bent crystals, which focus X-rays. The polycapillary optic can be used to focus X-rays emitted by the X-ray tube thereby increasing the X-ray flux on the sample over 1000 times. Polycapillaries will also be used to collect the X-rays from the excitation site and screen the radiation background from the radioactive species in the specimen. This dual-optic approach significantly reduces the background and increases the analyte signal thereby increasing the sensitivity of the analysis. A doubly bent crystal used as the focusing optic produces focused monochromatic X-ray excitation, which eliminates the bremsstrahlung background from the X-ray source. The coupling of the doubly bent crystal for monochromatic excitation with a polycapillary for signal collection can effectively eliminate the noise background and radiation background from the specimen. The integration of these X-ray optics increases the signal-to-noise and thereby increases the sensitivity of the analysis for low-level analytes. This work will address a key need for radiochemical analysis of high-level waste using a non-destructive, multi-element, and rapid method in a radiation environment. There is significant potential that this instrumentation could be capable of on-line analysis for process waste stream characterization at DOE sites.

Havrilla, George J.; Gao, Ning

2002-06-01

383

Proposed Imaging of the Ultrafast Electronic Motion in Samples using X-Ray Phase Contrast  

NASA Astrophysics Data System (ADS)

Tracing the motion of electrons has enormous relevance to understanding ubiquitous phenomena in ultrafast science, such as the dynamical evolution of the electron density during complex chemical and biological processes. Scattering of ultrashort x-ray pulses from an electronic wave packet would appear to be the most obvious approach to image the electronic motion in real time and real space with the notion that such scattering patterns, in the far-field regime, encode the instantaneous electron density of the wave packet. However, recent results by Dixit et al. [Proc. Natl. Acad. Sci. U.S.A. 109, 11 636 (2012)] have put this notion into question and have shown that the scattering in the far-field regime probes spatiotemporal density-density correlations. Here, we propose a possible way to image the instantaneous electron density of the wave packet via ultrafast x-ray phase contrast imaging. Moreover, we show that inelastic scattering processes, which plague ultrafast scattering in the far-field regime, do not contribute in ultrafast x-ray phase contrast imaging as a consequence of an interference effect. We illustrate our general findings by means of a wave packet that lies in the time and energy range of the dynamics of valence electrons in complex molecular and biological systems. This present work offers a potential to image not only instantaneous snapshots of nonstationary electron dynamics, but also the Laplacian of these snapshots which provide information about the complex bonding and topology of the charge distributions in the systems.

Dixit, Gopal; Slowik, Jan Malte; Santra, Robin

2013-03-01

384

Proposed imaging of the ultrafast electronic motion in samples using x-ray phase contrast.  

PubMed

Tracing the motion of electrons has enormous relevance to understanding ubiquitous phenomena in ultrafast science, such as the dynamical evolution of the electron density during complex chemical and biological processes. Scattering of ultrashort x-ray pulses from an electronic wave packet would appear to be the most obvious approach to image the electronic motion in real time and real space with the notion that such scattering patterns, in the far-field regime, encode the instantaneous electron density of the wave packet. However, recent results by Dixit et al. [Proc. Natl. Acad. Sci. U.S.A. 109, 11636 (2012)] have put this notion into question and have shown that the scattering in the far-field regime probes spatiotemporal density-density correlations. Here, we propose a possible way to image the instantaneous electron density of the wave packet via ultrafast x-ray phase contrast imaging. Moreover, we show that inelastic scattering processes, which plague ultrafast scattering in the far-field regime, do not contribute in ultrafast x-ray phase contrast imaging as a consequence of an interference effect. We illustrate our general findings by means of a wave packet that lies in the time and energy range of the dynamics of valence electrons in complex molecular and biological systems. This present work offers a potential to image not only instantaneous snapshots of nonstationary electron dynamics, but also the laplacian of these snapshots which provide information about the complex bonding and topology of the charge distributions in the systems. PMID:23581370

Dixit, Gopal; Slowik, Jan Malte; Santra, Robin

2013-03-29

385

X-ray diffraction study of aluminum oxide. II. full-profile x-ray analysis of low-temperature forms  

SciTech Connect

A full-profile analysis has been made of the x-ray diffraction patterns of lowtemperature forms of aluminum oxide. Structural models are proposed for these forms, describing the experimental data with a high confidence factor.

Ushakov, V.A.; Moroz, E.M.

1986-02-01

386

Unveiling Obscured AGN with X-ray Spectral Analysis  

NASA Astrophysics Data System (ADS)

With the recent advent of physically motivated, self-consistent X-ray models, the circumnuclear medium enshrouding AGN can now be investigated in unprecedented detail. We applied these models to 19 SDSS [OIII] 5007 Angstrom selected Type 2 AGN, where 9 are local Seyfert 2 galaxies and 10 are more luminous and distant Type 2 quasars. For the first time in a sample of AGN, we constrained both the line-of-sight and global column densities, finding that over half (11/19) are heavily obscured or Compton-thick (NH > 10^23 cm^-2). Four objects have different global from line-of-sight column densities. When correcting the observed X-ray luminosities for obscuration, the L_x/L_[OIII] ratio for these Type 2 AGN is essentially identical to the Seyfert 1 (i.e., unabsorbed AGN) value, which is consistent with both parameters cleanly probing AGN emission.

LaMassa, Stephanie M.; Yaqoob, Tahir; Ptak, Andrew; Jia, Jianjun; Heckman, Timothy M.; Gandhi, Poshak; Urry, C. Megan

2014-06-01

387

X-ray diffraction analysis of Si0 2 structure  

Microsoft Academic Search

The structural differences between vitreous silica and porous Si02 glass prepared by chemical extraction of Na20 · B203 · Si02 glasses were analysed by the method of X-ray diffraction. These investigations have given evidence for regularities of continuous silica networks beyond the well known short-range order which are discussed with respect to network topology. This network topology will be considered

B. Himmel; Th. Gerber; W. Heyer; W. Blau

1987-01-01

388

Analysis of X-ray radiography in atomizing sprays  

NASA Astrophysics Data System (ADS)

Recent studies of spray-related flowfields using synchrotron-based X-ray radiography at the Advanced Photon Source (APS), Argonne National Lab, have produced useful results related to fuel mass. A companion article to this one analyzed X-ray phase contrast imaging and it identified several problems. Those results could potentially raise questions about radiography as well. Here, we simulate X-ray radiography using the same computational tools as before, but we reach a different set of conclusions. One important finding is the demonstration that radiography detects the total liquid mass along a line-of-sight, including both drops and intact liquid. As such, it can reveal liquid mass fraction, which is related to the spray breakup rate and gas entrainment; both critical for understanding of sprays. The potential for confusion between local signal reduction by diffraction and local signal reduction by absorption is also discussed. The issue is not unusual in such circumstances. This potential background problem can be avoided by careful arrangement of the experiment, and it is clear that it does not affect the results produced by the APS.

Linne, Mark

2012-09-01

389

Numerical analysis as applied to x-ray scattering curves  

SciTech Connect

Various numerical methods involving polynomials were employed for both interpolation and linear least-square curve fitting of the atomic scattering factors of x-ray diffraction. This included use of Lagrangian and orthogonal Legendre polynomials, as well as cubic spline and Stineman interpolation. Interpolation is a method that uniquely matches known data points within small segments of an unknown curve to approximate points in between. Special emphasis was placed on establishing both the minimum grid spacing and polynomial degree that are needed to perform accurate interpolations. The grid spacing in a region of the x-argument near 1.0 A/sup -1/ that is commonly employed in standard tabulations of x-ray scattering factors was found to be too coarse for wholly accurate interpolation by polynomials of low degree. Least-squares curve fitting is a procedure that approximates the entire unknown curve with an analytical function that matches the known data points as closely as possible by minimizing the sum of their squared deviations from the fitted curve. Analytical representations of x-ray scattering curves are advantageous, since otherwise the complete scattering table must be sorted and the values of individual scattering factors derived by interpolation.

Jeffries, T.V.

1987-01-01

390

ANALYSIS AND MITIGATION OF X-RAY HAZARD GENERATED FROM HIGH INTENSITY LASER-TARGET INTERACTIONS  

SciTech Connect

Interaction of a high intensity laser with matter may generate an ionizing radiation hazard. Very limited studies have been made, however, on the laser-induced radiation protection issue. This work reviews available literature on the physics and characteristics of laser-induced X-ray hazards. Important aspects include the laser-to-electron energy conversion efficiency, electron angular distribution, electron energy spectrum and effective temperature, and bremsstrahlung production of X-rays in the target. The possible X-ray dose rates for several femtosecond Ti:sapphire laser systems used at SLAC, including the short pulse laser system for the Matter in Extreme Conditions Instrument (peak power 4 TW and peak intensity 2.4 x 10{sup 18} W/cm{sup 2}) were analysed. A graded approach to mitigate the laser-induced X-ray hazard with a combination of engineered and administrative controls is also proposed.

Qiu, R.; Liu, J.C.; Prinz, A.A.; Rokni, S.H.; Woods, M.; Xia, Z.; /SLAC; ,

2011-03-21

391

Electron contamination of a high-energy X-ray beam.  

PubMed

The Lorentz force on an electron is utilised to separate out the electron component from the open beam of a Clinac-18, operating in the X-ray mode. The experimental arrangement is such that the mixed beam (comprising the primary photons, the scattered photons and the contamination electrons) enters an external magnetic field, which is perpendicular to the central axis of the beam. The electron contribution is analysed as a function of collimator setting, depth and distance. Based on the data, one is led to believe that the shift in dmax with field size is due to a relative enhancement in the soft X-ray component as the collimator jaws are opened. PMID:733897

Padikal, T N; Deye, J A

1978-11-01

392

Quasi-monoenergetic Electron Acceleration for All-optical Ultrashort X-ray Source  

NASA Astrophysics Data System (ADS)

In laser-driven plasma acceleration, which is charged particle acceleration via the interaction of an intense laser pulse with a plasma, the accelerating electric field is a thousand times higher than that of conventional radio-frequency accelerators. Such high accelerating field enables a compact accelerator. Recently, the generation of quasi-monoenergetic electron beams has been demonstrated and the way toward a practical, compact electron accelerator is opened. Furthermore, the electron pulse duration is extremely short, of the order of femtosecond in laser-driven plasma acceleration. This set of unique characteristics opens the way toward a novel, compact, all-optical, ultrashort X-ray source based on such as laser Compton scattering scheme. The present status of the quasi-monoenergetic electron acceleration and prospect for all-optical ultrashort X-ray sources are reviewed.

Miura, Eisuke; Masuda, Shin-Ichi

393

Duplex multiwire proportional x-ray detector for multichord time-resolved soft x-ray and electron temperature measurements on T-10 tokamak.  

PubMed

Compact 64-channel multiwire proportional chamber is successfully used on T-10 and TCV tokamaks as a continuous-current soft x-ray detectors. The duplex multiwire proportional x-ray detector is a new generation of these detectors. It has been designed for simultaneous multichord measurement of plasma soft x-ray emissivity in a two spectral ranges and determination of the electron temperature by the two-absorber method. The detector consists of two identical multiwire proportional chambers filled by 90%Kr+10%CH(4) gas mixture at atmospheric pressure. The first multiwire chamber has 64 channels. The second multiwire chamber (installed behind the first one) has 32 channels. Both chambers view the plasma through the one helium-filled slot-hole camera. Thus, the first multiwire chamber serves as an absorber filter for the second one. Such construction of the detector allows us in addition to soft x-ray measurements to provide measurement of the plasma core electron temperature with spatial resolution of about 2 cm and a time resolution of less than 50 mus. The construction of the detector and experimental results illustrating the potential of the diagnostic are presented. PMID:19044481

Sushkov, A V; Andreev, V F; Kravtsov, D E

2008-10-01

394

Duplex multiwire proportional x-ray detector for multichord time-resolved soft x-ray and electron temperature measurements on T-10 tokamak  

SciTech Connect

Compact 64-channel multiwire proportional chamber is successfully used on T-10 and TCV tokamaks as a continuous-current soft x-ray detectors. The duplex multiwire proportional x-ray detector is a new generation of these detectors. It has been designed for simultaneous multichord measurement of plasma soft x-ray emissivity in a two spectral ranges and determination of the electron temperature by the two-absorber method. The detector consists of two identical multiwire proportional chambers filled by 90%Kr+10%CH{sub 4} gas mixture at atmospheric pressure. The first multiwire chamber has 64 channels. The second multiwire chamber (installed behind the first one) has 32 channels. Both chambers view the plasma through the one helium-filled slot-hole camera. Thus, the first multiwire chamber serves as an absorber filter for the second one. Such construction of the detector allows us in addition to soft x-ray measurements to provide measurement of the plasma core electron temperature with spatial resolution of about 2 cm and a time resolution of less than 50 {mu}s. The construction of the detector and experimental results illustrating the potential of the diagnostic are presented.

Sushkov, A. V.; Andreev, V. F.; Kravtsov, D. E. [Russian Research Centre Kurchatov Institute, 123182 Moscow (Russian Federation)

2008-10-15

395

Theory of multi-electron recoil effects on x-ray lineshapes of metals  

SciTech Connect

Within the change of self-consistent field approximation, x-ray spectra can be considerably richer in many-electron phenomena than once suspected. With the finite number of electrons method, these spectra can be evaluated for realistic electron-hole interactions in free electron metals. Preliminary results indicate that metals with band structure can also be treated this way. However, theories of final-state interactions in metals await the reliable determinations of the screened potential of a core hole in a metal and realistic avaluation of the effects of electron-electron interactions. (GHT)

Dow, J. D.; Swarts, C. A.; Bowen, M. A.; Mehreteab, E.; Satpathy, S. S.

1980-01-01

396

IDENTIFICATION OF SELECTED SILICATE MINERALS AND THEIR ASBESTIFORM VARIETIES BY ELECTRON OPTICAL AND X-RAY TECHNIQUES  

EPA Science Inventory

Illustrations of electron micrographs showing morphology, electron diffraction patterns, energy dispersive X-ray spectra, and X-ray diffraction patterns of selected silicates and their asbestiform varieties are presented as an aid in their identification. A method for preparing r...

397

Large format imaging detectors for x-ray free-electron-lasers  

NASA Astrophysics Data System (ADS)

New generation synchrotron light sources, the X-ray free electron lasers, require a two dimensional focal plane instrumentation to perform X-ray imaging from below 100eV up to 25keV. The instruments have to face the accelerator bunch structure and energy bandwidth which is different for existing (FLASH, Hamburg and LCLS, Menlo Park) and future photon sources (SACLA, Harima and XFEL, Hamburg). Within the frame of the Center for Free Electron Laser Science (CFEL), a joint effort of the Max-Planck Society, DESY and the University of Hamburg, the MPI semiconductor laboratory developed, produced and operated large area X-ray CCD detectors with a format of nearly 60cm2 image area. They show outstanding characteristics: a high readout speed due to a complete parallel signal processing, high and homogeneous quantum efficiency, low signal noise, radiation hardness and a high pixel charge handling capacitance. We will present measurement results which demonstrate the X-ray spectroscopic and imaging capabilities of the fabricated devices. We will also report on the concept and the anticipated properties of the full, large scale system. The implementation of the detector into an experimental chamber to perform measurements e.g. of macromolecules in order to determine their structure at atomic resolutions will be shown.

Hartmann, Robert; Epp, Sascha; Gorke, Hubert; Hartmann, Andreas; Hauser, Günther; Herrmann, Sven; Holl, Peter; Kimmel, Nils; Meidinger, Norbert; Reich, Christian; Rolles, Daniel; Soltau, Heike; Strüder, Lothar; Ullrich, Joachim; Weidenspointner, Georg

2011-05-01

398

Refractive microlens array for wave-front analysis in the medium to hard x-ray range  

NASA Astrophysics Data System (ADS)

We report an alternative approach to x-ray wave-front analysis that uses a refractive microlens array as a Shack-Hartmann sensor. The sensor was manufactured by self-assembly and electroplating techniques and is suitable for high-resolution wave-front analysis of medium to hard x rays. We demonstrate its effectiveness at an x-ray energy of 3 keV for analysis of x-ray wave-front perturbations caused by microscopic objects. The sensor has potential advantages over other methods for x-ray phase imaging and will also be useful for the characterization of x-ray beams and optics.

Mayo, Sheridan C.; Sexton, Brett

2004-04-01

399

X-Ray Fluorescence (XRF) spectrometry for materials analysis and discovering "the atomic number"  

NSDL National Science Digital Library

In this experiment students use XRF spectroscopy to analyze a sampleâs elemental composition. From the characteristic X-ray energies, Moseleyâs Law, a proof of the existence of the atomic number, is verified. The atomic number increases in regular steps with an increase in the characteristic X-ray energy. We will use this relationship to find the Rydbergâs energy constant and screening coefficient for K X-rays. This lab is designed for the student to learn to: 1. differentiate between characteristic X-rays and Bremsstrahlung radiations, 2. use characteristic X-rays to identify elements, 3. acquire a spectrum, calibrate it and use it for qualitative (element identification) as well as quantitative (elemental concentration) analysis, and finally, 4. verify Moseleyâs law and the validity of an atomic number.

Khalid, Asma; Khan, Aleena T.; Anwar, Muhammad S.

2012-06-06

400

Femtosecond and Subfemtosecond X-Ray Pulses from a SASE Based Free-Electron Laser  

SciTech Connect

We propose a novel method to generate femtosecond and sub-femtosecond photon pulses in a free electron laser by selectively spoiling the transverse emittance of the electron beam. Its merits are simplicity and ease of implementation. When the system is applied to the Linac Coherent Light Source, it can provide x-ray pulses the order of 1 femtosecond in duration containing about 1010 transversely coherent photons.

Emma, P

2004-03-10

401

Liberation of Neutrons from Beryllium by X-Rays: Radioactivity Induced by Means of Electron Tubes  

Microsoft Academic Search

IT has been recently reported1 that neutrons are liberated from beryllium by gamma-rays of radium and that these are able to induce radioactivity in iodine. Following up this work, we have attempted to liberate neutrons from beryllium by means of hard X-rays, produced by high-voltage electron tubes. An electron tube, which could conveniently be operated by a high-voltage impulse generator

A. Brasch; F. Lange; A. Waly; T. E. Banks; T. A. Chalmers; Leo Szilard; F. L. Hopwood

1934-01-01

402

Characterization of laboratory weathered labradorite surfaces using X-ray photoelectron spectroscopy and transmission electron microscopy  

Microsoft Academic Search

Altered surfaces of labradorite resulting from laboratory weathering at pH 4 and 25°C were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). SEM micrographs showed nonuniform surface alteration of labradorite weathered at pH 3.7 for 415 days. TEM micrographs showed exsolution lamellae of a more calcic-rich and more sodic-rich phase, each averaging approximately

William P. Inskeep; Edward A. Nater; Paul R. Bloom; Dirk S. Vandervoort; M. Susan Erich

1991-01-01

403

Characterization of laboratory weathered labradorite surfaces using X-ray photoelectron spectroscopy and transmission electron microscopy  

Microsoft Academic Search

Altered surfaces of labradorite resulting from laboratory weathering at pH 4 and 25C were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). SEM micrographs showed nonuniform surface alteration of labradorite weathered at pH 3.7 for 415 days. TEM micrographs showed exsolution lamellae of a more calcic-rich and more sodic-rich phase, each averaging approximately

W. P. Inskeep; D. S. Vandervoort; E. A. Nater; P. R. Bloom; M. S. Erich

1991-01-01

404

X-ray pulse generation via laser Compton scattering using quasi-monoenergetic electron beam driven by laser acceleration  

NASA Astrophysics Data System (ADS)

We have demonstrated X-ray generation via laser Compton scattering using a laser-accelerated quasi-monoenergetic electron beam. X-rays were generated by scattering a femtosecond laser pulse (800 nm, 140 mJ, 100 fs) off a quasi-monoenergetic electron beam containing 70 pC electrons in the monoenergetic peak with an energy of 60 MeV produced by focusing an intense laser pulse (800 nm, 700 mJ, 40 fs) on a helium gas jet. A well-collimated X-ray beam with a divergence angle of approximately 5 mrad was generated. The number of X-ray photons was estimated to be 2x10^7 per pulse. The characteristics of X-rays were also investigated using simulation. The spectrum of X-rays emitted within the scattered angle of 5 mrad had a quasi-monochromatic structure with a peak at 60 keV. The number of X-ray photons was 1.8 x10^7, which was in a good agreement with the experimental result. The allowance delay range between the two laser pulses for X-ray generation was approximately 100 fs, and was nearly equal to the duration of the laser pulse scattered by the electron pulse. This suggests that the X-ray pulse duration was shorter than 100 fs.

Miura, Eisuke; Kuroda, Ryunosuke; Toyokawa, Hiroyuki

2012-10-01

405

Electronic Structure of AC-Clusters and High-Resolution X-ray Spectra of Actinides in Solids  

SciTech Connect

Ab initio calculations using SCF approach for and analysis of results of investigation of the electronic structure of the clusters RAn+:[L]k with rare earths or actinides were carried out for the clusters in solids and liquids. Theoretical results for the electronic structure, radial integrals and energy of X- ray lines are presented for AC ions with unoccupied 5f-shell in the clusters in oxides, chlorides and fluorides environment. Possibility of collapse of nf-shell for the separate clusters and identification of electronic state of ions with unstable nuclei, are discussed, too. (author)

Kulagin, Nicolay Alex [Physics Department, Kharkov National University for Radio Electronics, Khakov (Ukraine)

2007-07-01

406

Energetic Electrons in Solar Flares - As Viewed in X-Rays  

NASA Technical Reports Server (NTRS)

Hard X-ray observations provide the most direct diagnostic we have of the suprathermal electrons and the hottest thermal plasma present in solar flares. The Ramaty High Energy Solar Spectroscopic Imager (RHESSI) is obtaining the most comprehensive observations of individual solar flares ever available in hard X-rays. For the first time, high-resolution spectra are available for a large number of flares that accurately display the spectral shape and its evolution and, in many cases, allow us to identify the transition from the bremsstrahlung X-rays produced by suprathermal electrons to the bremsstrahlung at lower energies emitted by thermal plasma. Also, for the first time, images can be produced in arbitrary energy bands above 3 keV, and spectra of distinct imaged components can be obtained. I will review what we have learned from RHESSI observations about flare suprathermal electron distributions and their evolution Next, I will present computations of the energy deposited by these suprathermal electrons in individual flares and compare this with the energy contained in the hot thermal plasma. I will point out unsolved problems in deducing both suprathermal electron distributions and the energy content of the thermal plasma, and discuss possible solutions. Finally, I will present evidence that electron acceleration is associated with magnetic reconnection in the corona.

Holman, Gordon D.

2004-01-01

407

A hot-electron microcalorimeter for X-ray detection using a superconducting transition edge sensor with electrothermal feedback  

Microsoft Academic Search

We investigate a hot-electron microcalorimeter for X-ray detection. The X-ray absorber consists of a normal metal film in thermal and electrical contact with a superconducting transition-edge sensor. The sensor is formed by a proximity-effect bilayer of aluminum and silver, with a sharp superconducting transition near 100 mK. Energy from X-rays absorbed in the normal film is removed by a reduction

K. D Irwin; G. C Hilton; J. M Martinis; B Cabrera

1996-01-01

408

Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser  

PubMed Central

Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with a sensitivity not hitherto possible. Although DCH ionization on a single site in molecules was recently measured with double- and single-photon absorption, double-core holes with single vacancies on two different sites, allowing unambiguous chemical analysis, have remained elusive. Here we report that direct observation of double-core holes with single vacancies on two different sites produced via sequential two-photon absorption, using short, intense X-ray pulses from the Linac Coherent Light Source free-electron laser and compare it with theoretical modeling. The observation of DCH states, which exhibit a unique signature, and agreement with theory proves the feasibility of the method. Our findings exploit the ultrashort pulse duration of the free-electron laser to eject two core electrons on a time scale comparable to that of Auger decay and demonstrate possible future X-ray control of physical inner-shell processes.

Berrah, Nora; Fang, Li; Murphy, Brendan; Osipov, Timur; Ueda, Kiyoshi; Kukk, Edwin; Feifel, Raimund; van der Meulen, Peter; Salen, Peter; Schmidt, Henning T.; Thomas, Richard D.; Larsson, Mats; Richter, Robert; Prince, Kevin C.; Bozek, John D.; Bostedt, Christoph; Wada, Shin-ichi; Piancastelli, Maria N.; Tashiro, Motomichi; Ehara, Masahiro

2011-01-01

409

Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser.  

PubMed

Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with a sensitivity not hitherto possible. Although DCH ionization on a single site in molecules was recently measured with double- and single-photon absorption, double-core holes with single vacancies on two different sites, allowing unambiguous chemical analysis, have remained elusive. Here we report that direct observation of double-core holes with single vacancies on two different sites produced via sequential two-photon absorption, using short, intense X-ray pulses from the Linac Coherent Light Source free-electron laser and compare it with theoretical modeling. The observation of DCH states, which exhibit a unique signature, and agreement with theory proves the feasibility of the method. Our findings exploit the ultrashort pulse duration of the free-electron laser to eject two core electrons on a time scale comparable to that of Auger decay and demonstrate possible future X-ray control of physical inner-shell processes. PMID:21969540

Berrah, Nora; Fang, Li; Murphy, Brendan; Osipov, Timur; Ueda, Kiyoshi; Kukk, Edwin; Feifel, Raimund; van der Meulen, Peter; Salen, Peter; Schmidt, Henning T; Thomas, Richard D; Larsson, Mats; Richter, Robert; Prince, Kevin C; Bozek, John D; Bostedt, Christoph; Wada, Shin-ichi; Piancastelli, Maria N; Tashiro, Motomichi; Ehara, Masahiro

2011-10-11

410

A compact X-ray free-electron laser emitting in the sub-ångström region  

NASA Astrophysics Data System (ADS)

The free-electron laser, first proposed by Madey in 1971, has significantly reduced laser wavelengths to the vacuum ultraviolet and soft X-ray regions. Recently, an X-ray free-electron laser (XFEL) was operated at 1.2 Å at the Linac Coherent Light Source (LCLS). Here, we report the successful generation of sub-ångström laser light using a compact XFEL source, combining a short-period undulator with an 8 GeV electron beam. The shortest wavelength attained--0.634 Å (63.4 pm)--is four orders of magnitude smaller than the 694 nm generated by Maiman's first laser. The maximum power exceeded 10 GW with a pulse duration of 10-14 s. This achievement will contribute to the widespread use of XFEL sources and provide broad opportunities for exploring new fields in science.

Ishikawa, Tetsuya; Aoyagi, Hideki; Asaka, Takao; Asano, Yoshihiro; Azumi, Noriyoshi; Bizen, Teruhiko; Ego, Hiroyasu; Fukami, Kenji; Fukui, Toru; Furukawa, Yukito; Goto, Shunji; Hanaki, Hirofumi; Hara, Toru; Hasegawa, Teruaki; Hatsui, Takaki; Higashiya, Atsushi; Hirono, Toko; Hosoda, Naoyasu; Ishii, Miho; Inagaki, Takahiro; Inubushi, Yuichi; Itoga, Toshiro; Joti, Yasumasa; Kago, Masahiro; Kameshima, Takashi; Kimura, Hiroaki; Kirihara, Yoichi; Kiyomichi, Akio; Kobayashi, Toshiaki; Kondo, Chikara; Kudo, Togo; Maesaka, Hirokazu; Maréchal, Xavier M.; Masuda, Takemasa; Matsubara, Shinichi; Matsumoto, Takahiro; Matsushita, Tomohiro; Matsui, Sakuo; Nagasono, Mitsuru; Nariyama, Nobuteru; Ohashi, Haruhiko; Ohata, Toru; Ohshima, Takashi; Ono, Shun; Otake, Yuji; Saji, Choji; Sakurai, Tatsuyuki; Sato, Takahiro; Sawada, Kei; Seike, Takamitsu; Shirasawa, Katsutoshi; Sugimoto, Takashi; Suzuki, Shinsuke; Takahashi, Sunao; Takebe, Hideki; Takeshita, Kunikazu; Tamasaku, Kenji; Tanaka, Hitoshi; Tanaka, Ryotaro; Tanaka, Takashi; Togashi, Tadashi; Togawa, Kazuaki; Tokuhisa, Atsushi; Tomizawa, Hiromitsu; Tono, Kensuke; Wu, Shukui; Yabashi, Makina; Yamaga, Mitsuhiro; Yamashita, Akihiro; Yanagida, Kenichi; Zhang, Chao; Shintake, Tsumoru; Kitamura, Hideo; Kumagai, Noritaka

2012-08-01

411

Dominant Secondary Nuclear Photoexcitation with the X-Ray Free-Electron Laser  

NASA Astrophysics Data System (ADS)

The new regime of resonant nuclear photoexcitation rendered possible by x-ray free-electron laser beams interacting with solid state targets is investigated theoretically. Our results unexpectedly show that secondary processes coupling nuclei to the atomic shell in the created cold high-density plasma can dominate direct photoexcitation. As an example, we discuss the case of Mo93m isomer depletion for which nuclear excitation by electron capture as a secondary process is shown to be orders of magnitude more efficient than the direct laser-nucleus interaction. General arguments revisiting the role of the x-ray free-electron laser in nuclear experiments involving solid-state targets are further deduced.

Gunst, Jonas; Litvinov, Yuri A.; Keitel, Christoph H.; Pálffy, Adriana

2014-02-01

412

Enhanced harmonic generation in x-ray free-electron lasers  

NASA Astrophysics Data System (ADS)

Harmonic generation becomes increasingly important as x-ray free-electron lasers push to shorter wavelengths. Recent studies have pointed to the possibility of enhancing harmonic generation by detuning the fundamental. In x-ray free-electron lasers, the wiggler line is composed of multiple wiggler segments with magnetic quadrupoles in the gaps to provide for increased focusing. In this paper, we study the effect on harmonic generation in simulation by (1) varying the gap lengths between the wiggler segments and (2) varying the electron beam ? function. In studying the harmonic we find enhanced harmonic generation is periodic in the gap length and peaks are found as the wiggler separation varies by ? /3 (where ? is the fundamental wavelength), which corresponds to a phase shift of 2?/3. As a consequence, enhanced harmonic generation is found both when the fundamental emission is strong by the nonlinear harmonic generation mechanism and by linear harmonic generation when the fundamental is detuned.

Freund, H. P.; Yampolsky, N. A.; Marksteiner, Q.

2014-01-01

413

New approach to breast tumor detection based on fluorescence x-ray analysis  

PubMed Central

A new technical approach to breast-tumor detection is proposed. The technique is based on fluorescence x-ray analysis, and can identify a miniature malignant tumor within the breast. The primary beam intensity needed in fluorescence x-ray analysis is on a lower order of magnitude than that used in mammography. Thus, the newly-proposed technique would enable detection of a still tiny breast cancer while dramatically lowering the radiation dose. Field-emission x-ray sources might be a key for translating this concept into a medical technique.

Hayashi, Yasuhiko; Okuyama, Fumio

2010-01-01

414

Local x-ray structure analysis of optically manipulated biological micro-objects  

NASA Astrophysics Data System (ADS)

X-ray diffraction using micro- and nanofocused beams is well suited for nanostructure analysis at different sites of a biological micro-object. To conduct in vitro studies without mechanical contact, we developed object manipulation by optical tweezers in a microfluidic cell. Here we report x-ray microdiffraction analysis of a micro-object optically trapped in three dimensions. We revealed the nanostructure of a single starch granule at different points and investigated local radiation damage induced by repeated x-ray exposures at the same position, demonstrating high stability and full control of the granule orientation by multiple optical traps.

Cojoc, Dan; Amenitsch, Heinz; Ferrari, Enrico; Santucci, Silvia C.; Sartori, Barbara; Rappolt, Michael; Marmiroli, Benedetta; Burghammer, Manfred; Riekel, Christian

2010-12-01

415

X-ray and photoelectron spectroscopy of the structure, reactivity, and electronic structure of semiconductor nanocrystals  

SciTech Connect

Semiconductor nanocrystals are a system which has been the focus of interest due to their size dependent properties and their possible use in technological applications. Many chemical and physical properties vary systematically with the size of the nanocrystal and thus their study enables the investigation of scaling laws. Due to the increasing surface to volume ratio as size is decreased, the surfaces of nanocrystals are expected to have a large influence on their electronic, thermodynamic, and chemical behavior. In spite of their importance, nanocrystal surfaces are still relatively uncharacterized in terms of their structure, electronic properties, bonding, and reactivity. Investigation of nanocrystal surfaces is currently limited by what techniques to use, and which methods are suitable for nanocrystals is still being determined. This work presents experiments using x-ray and electronic spectroscopies to explore the structure, reactivity, and electronic properties of semiconductor (CdSe, InAs) nanocrystals and how they vary with size. Specifically, x-ray absorption near edge spectroscopy (XANES) in conjunction with multiple scattering simulations affords information about the structural disorder present at the surface of the nanocrystal. X-ray photoelectron spectroscopy (XPS) and ultra-violet photoelectron spectroscopy (UPS) probe the electronic structure in terms of hole screening, and also give information about band lineups when the nanocrystal is placed in electric contact with a substrate. XPS of the core levels of the nanocrystal as a function of photo-oxidation time yields kinetic data on the oxidation reaction occurring at the surface of the nanocrystal.

Hamad, K.S.

2000-05-01

416

Quantitative analysis of single aerosol particles using polycapillary X-ray optics  

NASA Astrophysics Data System (ADS)

A laboratory micro X-ray fluorescence spectrometer based on polycapillary X-ray optics (PXRO) was used to carry out the quantitative X-ray fluorescence analysis of single aerosol particles with smaller size than that of focal spot of PXRO. The minimum detection limits measured with the thin-film reference standards were in the range from 13.3 to 0.7 ng cm - 2 when the operating current and voltage were 70 mA and 35 kV, respectively. In order to reduce the effects of the inhomogeneous distributions of the X-ray intensity in the focal spot of the PXRO on the analysis results, the sensitivities were corrected by using a Gaussian function for the quantitative analysis of single aerosol particles. The accuracy of the analysis of single standard solution drops was on average 25% depending on the element and concentration. The precision of the analysis was better than 5%.

Sun, Tianxi; Liu, Zhiguo; Li, Yude; Wang, Guangfu; Zhu, Guanghua; Ding, Xunliang; Xu, Qing; Liu, Hui; Luo, Ping; Pan, Qiuli; Lin, Xiaoyan; Teng, Yuepeng

2009-11-01

417

Hard x-ray tomographic studies of the destruction of an energetic electron ring.  

PubMed

A tomography system was designed and built at the Large Plasma Device to measure the spatial distribution of hard x-ray (100 KeV-3 MeV) emissivity. The x-rays were generated when a hot electron ring was significantly disrupted by a shear Alfvén wave. The plasma is pulsed at 1 Hz (1 shot/s). A lead shielded scintillator detector with an acceptance angle defined by a lead pinhole is mounted on a rotary gimbal and used to detect the x-rays. The system measures one chord per plasma shot using only one detector. A data plane usually consists of several hundred chords. A novel Dot by Dot Reconstruction (DDR) method is introduced to calculate the emissivity profile from the line integrated data. In the experiments, there are often physical obstructions, which make measurements at certain angles impossible. The DDR method works well even in this situation. The method was tested with simulated data, and was found to be more effective than previously published methods for the specific geometry of this experiment. The reconstructed x-ray emissivity from experimental data by this method is shown. PMID:23742547

Wang, Y; Gekelman, W; Pribyl, P

2013-05-01

418

Analysis and interpretation of X-ray pulsars  

NASA Technical Reports Server (NTRS)

By careful measurements of the fluctuations in pulsar pulse periods on time scales of days and longer, researchers determined that these fluctuations are caused by changes in the rotation rate of the stellar crust apparently arising from matter accretion. The study of these fluctuations is a particularly promising way to determine the properties of accreting pulsars, because stellar rotation is relatively simple in comparison to much other X-ray source physics and can be investigated in detail. Rotation rates can be determined precisely.

Boynton, Paul E.; Deeter, John E.

1987-01-01

419

Auger Electrons via K? X-Ray Lines of Platinum Compounds for Nanotechnological Applications  

NASA Astrophysics Data System (ADS)

We will report study on the K? X-ray lines of platinum. Pt compounds, such as cisplatin, are common in biomedical applications. The active element Pt can emit or absorb hard X-rays. We have obtained the photoionization cross sections from the oscillator strengths of 1s-2p (K?) transitions in Pt ions. We find that these transitions appear as resonances in photoionization in the hard X-ray energy range of 64 - 71 keV (0.18 - 0.17 Å) below the K-shell ionization and with a strength orders of magnitude higher compared to that at the K-shell ionization. This is the focus of our study for possible initiation of an emission cascade of Auger electrons at the resonant energy. We will present the oscillator strengths and attenuation coefficients per unit mass for all the K? transitions in the event platinum cascades through various, namely from fluorine-like to hydrogen like, ionic states. The study is motivated by uur proposed method, Resonant Theranosticsb,C (RT) for biomedical appliations, which aims to find narrow band X-ray energy that corresponds to resonant photo-absorption and leads to emission of Auger electrons. As the next step of the RT method we will also report on experimental results on producing monochromatic X-rays, targeted to the resonant energy, from the wide band Bremstruhlung radiation of a conventional X-ray source. Partially support: DOE, Computational Facility: Ohio Supercomputer Center, Columbus, Ohio. "Resonant X-Ray Enhancement of the Auger Effect in High-Z atoms, molecules, and Nanoparticles: Biomedical Applications", A.K. Pradhan, S.N. Nahar, M. Montenegro, Yan Yu, H.L. Zhang, C. Sur, M. Mrozik, R.M. Pitzer, J. of Phys. Chem. A, 113 (2009), 12356. "Monte Carlo Simulations and Atomic Calculations for Auger Processes in Biomedical Nanotheranostics", M. Montenegro, S. N. Nahar, A. K. Pradhan, Ke Huang, Yan Yu, J. of Phys. Chem. A, 113 (2009), 12364.

Nahar, Sultana N.; Lim, Sara; Pradhan, A. K.; Pitzer, R. M.

2011-06-01