摘要:

©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291749

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Photoemission electron microscopy (PEEM) is a full field imaging technique where x-ray exited electrons are used to form an image of the sample surface as a function of the x-ray photon energy and polarization. Contrast in PEEM can be due to a number of mechanisms including topographical, work function, elemental, chemical, polarization, x-ray magnetic circular and linear dichroism contrast. This wide range of contrast mechanisms together with the surface sensitivity and high spatial resolution make PEEM a very useful tool for the study of magnetic materials. PEEM-II is a new microscope installed at the bending magnet beamline 7.3.1.1 of the Advanced Light Source. In the present paper we describe the design and features of PEEM-II, and show results of our recent studies. Using PEEM and its elemental specificity, it is possible to investigate the various layers in magnetic multilayer structures independently. The experiments described here include the investigation of the switching behavior of magnetic multilayer structures that are of interest for magnetic RAM applications. The study of antiferromagnetic surfaces and thin films are of great importance for devices based on the effect of exchange bias. To date, studies at high-spatial-resolution of exchange bias systems has been difficult because of the lack of appropriate investigation methods. Here we demonstrate how PEEM has been used to image antiferromagnetic structure on surfaces with high spatial resolution. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291750

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The XM-1 x-ray microscope was built to obtain a high throughput of high-resolution transmission images with a wide variety of thick (< 10 micron) samples. Modeled after a “conventional” full-field microscope, the XM-1 makes use of zone plates (ZP) for the condenser and objective elements. We present an overview of the recent activities at XM-1. Over the past year many enhancements have taken place such as the use of more efficient zone plates and the development of a cryogenic sample stage. Moreover, we have been developing the spectromicroscopy capabilities of the microscope to distinguish different element and chemical states within a sample while obtaining high spatial resolution images. We report on these and other advances. Additionally, the microscope has been actively used in many fields including biology, environmental and material science. Some of these recent achievements will be highlighted as well. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291751

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The design considerations are described for a new class of instrumentation optimized for x-ray microdiffraction measurements of polycrystalline amples. A prototype station on the MHATT-Cat beamline 7 at the Advanced Photon Source is used to illustrate the current level of performance of this instrumentation. This station allows for efficient measurements of x-ray microdiffraction from polycrystalline materials with submicron spatial resolution and with strain resolution below 1 part in104.The station utilizes a specially designed monochromator/non-dispersive Kirkpatrick-Baez focusing system that allows for rapid oscillation between monochromatic and white beam conditions. This allows the deviatoric and full strain tensors of polycrystalline grains to be rapidly determined. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291752

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

A new x-ray microprobe beamline was recently installed and commissioned at the Center for Advanced Microstructures and Devices (CAMD), Louisiana State University. Due to the design of the beamline and the end-station, we are able to perform (i) spatially-resolved x-ray fluorescence spectroscopy using the broad intense spectrum of the white synchrotron radiation, and (ii) spatially-resolved x-ray absorption spectroscopy in the energy region of 2000 eV to 12000 eV. The set-up of the beamline and the microprobe end-station, including the Kirkpatrick-Baez focusing system, are described. First focusing experiments show that we achieve a horizontal and vertical focal spot size of18.8×7.0microns (&sgr;), respectively, being the limit given by the CAMD source size and demagnification. Initial experimental results featuring white light fluorescence maps and micro-XANES spectra are presented. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291753

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

We 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 our 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 objectives were achieved by careful thermal management and use of a novel mirror and crystal monochromator cooling geometry. All beamline optical components are water cooled, and the x-ray beam in the experiment station is stable in beam intensity, energy, and position over many days with no active feedback. Using a double-crystal Si(111) monochromator, we have obtained a focal spot size (FWHM) of0.15&hthinsp;&mgr;m(v)×1.0&hthinsp;&mgr;m(h),and a photon flux of4×109&hthinsp;photons/secat the focal spot, and thus a photon flux density gain of 15,000. A circular beam spot of 0.15 &mgr;m in diameter can be achieved by reducing the horizontal source size using a white beam slit located 43.5 meters upstream of the zone plate, with an order of magnitude less flux in the focal spot. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291754

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The XM-1 x-ray microscope was built to obtain high-resolution transmission images from a wide variety of thick (< 10 micron) samples. Modeled after a “conventional” full-field microscope, XM-1 makes use of zone plates (ZP) for the condenser and objective elements. The XM-1 x-ray microscope has been shown to have a spatial resolution of 36 nm by doing a 10&percent;–90&percent; edge scan across a knife edge. Moreover, the condenser ZP and pinhole combination yields good spectral resolution to &lgr;/&Dgr;&lgr; of 700. We have shown that with this energy resolution we can distinguish between different elements and some chemical states. We can see spectra with adequate signal to noise even for individual 36nm pixels. With these capabilities, we are beginning work on various experiments in which we will distinguish different chemical species of specific elements within a sample. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291755

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Synchrotron-based Far-IR Reflection Absorption Spectroscopy (Far-IRAS) is ideal for investigating low energy dynamics at surfaces. In particular, bonding modes between an adsorbate and substrate typically lie below 1000 cm−1and are more sensitive to the local geometrical and electronic structures. A bright synchrotron source affords the ability to investigate these low frequency modes at high resolution for restrictive experimental (throughputs) geometries. Furthermore, a grazing incidence geometry with a limited throughput is necessary to gain information about the bonds at the adsorbate/substrate interface especially for substrates that absorb infrared light. This technique, proven in studies of adsorbate/metal interfaces, is extended to study the interface between adsorbates and oxide substrates. Two approaches to this class of experiments will be introduced and the intrinsic noise limitations of each will be discussed. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291756

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Beamline U2B at the National Synchrotron Light Source has been designed and built as an infrared beamline dedicated to the study of biomedical problems. In 1997, the horizontal and vertical acceptances of Beamline U2B were increased in order to increase the overall flux of the beamline. A wedged, CVD diamond window separates the UHV vacuum of the VUV ring from the rough vacuum of the beamline. The endstation consists of a Nicolet Magna 860 step-scan FTIR and a NicPlan infrared microscope. The spectrometer is equipped with beamsplitter/detector combinations that permit data collection in the mid-and far-infrared regions. We have also made provisions for mounting an external detector (e.g. bolometer) for far infrared microspectroscopy. Thus far, Beamline U2B has been used to (1) perform chemical imaging of bone tissue and brain cells to address issues related to bone disease and epilepsy, respectively, and (2) examine time-resolved protein structure in the sub-millisecond folding of cytochrome c. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291757

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

It is planned to set up an infrared beamline at BESSY II, equipped with a Fourier transform spectrometer for microscopy and ellipsometry. We present computed brilliances for the infrared radiation from the edge and from the homogeneous field of a bending magnet, applying BESSY II related parameters. A large acceptance beamline has been designed. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1291758

出版商:AIP    

年代:1900

数据来源: AIP