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in creator/contributor: "Maser, J."

open access

A Theoretical Study of the Two-Dimensional Point Focusing by Two Multilayer Laue Lenses.

Hard x-ray point focusing by two crossed multilayer Laue lenses is studied using a full-wave modeling approach. This study shows that for a small numerical aperture, the two consecutive diffraction processes can be decoupled into two independent ones in respective directions. Using this theoretical tool, we investigated adverse effects of various misalignments on the 2D focus profile and discussed the tolerance to them. We also derived simple expressions that described the required alignment ac… more

Date: August 10, 2008

Creator: Yan,H.; Maser, J.; Kang, H.C.; Macrader, A. & Stephenson, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

X-ray microscopy resource center at the Advanced Light Source

An x-ray microscopy resource center for biological x-ray imaging vvill be built at the Advanced Light Source (ALS) in Berkeley. The unique high brightness of the ALS allows short exposure times and high image quality. Two microscopes, an x-ray microscope (XM) and a scanning x-ray microscope (SXM) are planned. These microscopes serve complementary needs. The XM gives images in parallel at comparable short exposure times, and the SXM is optimized for low radiation doses applied to the sample. The… more

Date: July 1, 1992

Creator: Meyer-Ilse, W.; Koike, M.; Beguiristain, R.; Maser, J. & Attwood, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

X-ray microscopy resource center at the Advanced Light Source

Date: July 1, 1992

Creator: Meyer-Ilse, W.; Koike, M.; Beguiristain, R.; Maser, J. & Attwood, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Implementation of x-ray microscopy and micro-XANES analysis for investigations of the cellular uptake and cellular metabolism of transition metals.

Micro-SRIXE (synchrotron-radiation-induced X-ray emission) and micro-XAS (X-ray absorption spectroscopy) were used to probe the uptake of exogenous metals by cells. The high flux and the sub-micron resolution of the hard X-ray microprobe, offer the experimenter the ability to obtain highly sensitive spatial and structural information of cellular elements. In this work the uptake of carcinogenic Cr(VI) was compared with that of a relatively non-toxic Cr(III) complex by micro-SRIXE mapping of who… more

Date: October 24, 2002

Creator: Dillon, C. T.; Kennedy, B. J.; Lay, P. A.; Lai, B.; Cai, Z.; Stampfl, A. P. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Intracellular localization of titanium dioxide-biomolecule nanocomposites.

Emerging areas of nanotechnology hold the promise of overcoming the limitations of existing technology for intracellular manipulation. These new developments include the creation of nanocomposites that can be introduced into the cells, targeted to specific subcellular sites, and subsequently used as platforms for initiation of intracellular processes dependent on or aided by locally high concentrations of specific molecules delivered as components of the nanocomposites. Nanocomposites that comb… more

Date: October 30, 2002

Creator: Paunesku, T.; Stojicevic, N.; Vogt, S.; Maser, J.; Lai, B.; Rajh, T. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High-efficiency diffractive x-ray optics from sectioned multilayers

We investigate the diffraction properties of sectioned multilayers in Laue (transmission) geometry, at hard x-ray energies (9.5 and 19.5 keV). Two samples are studied, a 200 period W/Si multilayer of 29 nm d-spacing, and a 2020 period Mo/Si multilayer of 7 nm d-spacing, with cross-section depths ranging from 2 to 17 {micro}m. Rocking curves across the Bragg reflections exhibit well-defined interference fringes originating from the depth of the sample. Efficiencies as high as 70% were obtained. … more

Date: December 14, 2004

Creator: Kang, H. C.; Stephenson, G. B.; Liu, C.; Conley, R.; Macrander, A. T.; Maser, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Synchrotron x-ray study of multilayers in Laue geometry

Zone plates with depth to zone-width ratios as large as 100 are needed for focusing of hard x-rays. Such high aspect ratios are challenging to produce by lithography. We are investigating the fabrication of high-aspect-ratio linear zone plates by multilayer deposition followed by sectioning. As an initial step in this work, we present a synchrotron x-ray study of constant-period multilayers diffracting in Laue (transmission) geometry. Data are presented from two samples: a 200 period W/Si multi… more

Date: July 21, 2004

Creator: Kang, H. C.; Stephenson, G. B.; Liu, C.; Conley, R.; Macrander, A. T.; Maser, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Near-field stacking of zone plates in the x-ray range.

We use Fresnel zone plates as focusing optics in hard x-ray microprobes at energies typically between 6 and 30 keV. While a spatial resolution close to 0.1 {micro}m can currently be achieved, highest spatial resolution is obtained only at reduced diffraction efficiency due to manufacturing limitations with respect to the aspect ratios of zone plates. To increase the effective thickness of zone plates, we are stacking several identical zone plates on-axis in close proximity. If the zone plates a… more

Date: September 20, 2002

Creator: Maser, J.; Lai, B.; Yun, W.; Shastri, S. D.; Cai, Z.; Rodrigues, W. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Performance of a high-resolution x-ray microprobe at the Advanced Photon Source.

The authors have developed a x-ray microprobe in the energy region from 6 to 20 keV using undulator radiation and zone-plate optics for microfocusing-based techniques and applications at a beamline at the Advanced Photon Source (APS). The performance of the beamline was shown to meet the design objectives, including preservation of the source brilliance and coherence, selectable transverse coherence length and energy bandwidth, high angular stability, and harmonic suppression of the beam. These… more

Date: December 20, 1999

Creator: Cai, Z.; Lai, B.; Yun, W.; McNulty, I.; Khounsary, A.; Maser, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Grain tracing and strain determination in a Be compact tension specimen using synchrotron radiation

X-ray synchrotron radiation of high (11 KeV) energy and high flux (10{sup 10} photons per square centimeter per second) has been used to measure strains and polycrystallinity in 6-mm thick polycrystalline beryllium compact tension (CT) specimens at and around the crack tip (for fatigue-precracked sample) or at chevron notch point under load or no-load conditions. The authors demonstrated the feasibility strain field mapping as well as determining the polycrystallinity at or near the points of m… more

Date: April 19, 1999

Creator: Varma, R.; Green, R.; Garcia, M. D.; Satyam, P. V.; Yun, W. B.; Maser, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Use of the high-energy x-ray microprobe at the Advanced Photon Source to investigate the interactions between metals and bacteria.

Understanding the fate of heavy-metal contaminants in the environment is of fundamental importance in the development and evaluation of effective remediation and sequestration strategies. Among the factors influencing the transport of these contaminants are their chemical separation and the chemical and physical attributes of the surrounding medium. Bacteria and the extracellular material associated with them are thought to play a key role in determining a contaminant's speciation and thus its … more

Date: September 30, 1999

Creator: Kemner, K. M.; Lai, B.; Maser, J.; Schneegurt, M. A.; Cai, Z.; Ilinski, P. P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High-resolution x-ray imaging for microbiology at the Advanced Photon Source

Exciting new applications of high-resolution x-ray imaging have emerged recently due to major advances in high-brilliance synchrotrons sources and high-performance zone plate optics. Imaging with submicron resolution is now routine with hard x-rays: the authors have demonstrated 150 run in the 6--10 keV range with x-ray microscopes at the Advanced Photon Source (APS), a third-generation synchrotrons radiation facility. This has fueled interest in using x-ray imaging in applications ranging from… more

Date: November 2, 1999

Creator: Lai, B.; Kemner, K. M.; Maser, J.; Schneegurt, M. A.; Cai, Z.; Ilinski, P. P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Performance of hard X-ray zone plates at the Advanced Photon Source

Fresnel zone plates have been highly successful as focusing and imaging optics for soft x-ray microscopes and microprobe. More recently, with the advent of third-generation high-energy storage rings, zone plates for the hard x-ray regime have been put to use as well. The performance of zone plates manufactured using a combination of electron-beam lithography and x-ray lithography is described.

Date: December 20, 1999

Creator: Maser, J.; Lai, B.; Cai, Z.; Rodrigues, W.; Legnini, D.; Ilinski, P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A water-cooled x-ray monochromator for using off-axis undulator beam.

Undulator beamlines at third-generation synchrotrons x-ray sources are designed to use the high-brilliance radiation that is contained in the central cone of the generated x-ray beams. The rest of the x-ray beam is often unused. Moreover, in some cases, such as in the zone-plate-based microfocusing beamlines, only a small part of the central radiation cone around the optical axis is used. In this paper, a side-station branch line at the Advanced Photon Source that takes advantage of some of the… more

Date: December 11, 2000

Creator: Khounsary, A. & Maser, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A hard x-ray scanning microprobe for fluorescence imaging and microdiffraction at the Advanced Photon Source

A hard x-ray scanning microprobe based on zone plate optics and undulator radiation, in the energy region from 6 to 20 keV, has reached a focal spot size (FWHM) of 0.15 {micro}m (v) x 0.6 {micro}m (h), and a photon flux of 4 x 10{sup 9} photons/sec/0.01%BW. Using a slit 44 meters upstream to create a virtual source, a circular beam spot of 0.15 {micro}m in diameter can be obtained with a photon flux of one order of magnitude less. During fluorescence mapping of trace elements in a single human … more

Date: November 2, 1999

Creator: Cai, L.; Lai, B.; Yun, W.; Ilinski, P.; Legnini, D.; Maser, J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department