摘要:

The recent observation of strong amplification on multikilovolt Xe(L) hollow atom transitions in the ∼2.8 Å spectral region can be seen as a consequence of the combination of (1) a new concept for amplification that involves the creation of a highly ordered state combining ionic, plasma, and coherent radiative components and (2) the use of two recently discovered (c. ∼1990) forms of radially symmetric energetic matter, namely, hollow atoms and self‐trapped plasma channels. This approach enables the demanding power densities necessary for x‐ray amplification (∼1019W/cm3) to be reached under conditions for which (&agr;) the effective phase space volume of the interaction is profoundly limited and (&bgr;) the energy transfer is radiation dominated. A leading application will be the realization of a new mode of microimaging of living biological matter having a spatial resolution ∼1000‐fold superior to conventional light microscopy. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796571

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

I review recent studies of X‐ray generation based on Laser‐Compton scattering. Especially, our recent experimental results for the generation of &ggr;‐rays and plans for X‐ray generation will be explained. The stability of the photon beam source by the Laser‐Compton scattering will also be discussed from issues of laser and electron beam stability. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796572

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The Synchrotron Light Life Science Center of Ritsumeikan University seeks the next generation life science beyond genomics and proteomics by the unique portable synchrotrons named MIRROCLE. MIRRORCLE‐6X generates brilliant hard x‐rays in spite of its 6‐MeV electron energy. The power of IR/FIR beam from MIRRORCLE‐20 is much higher than any synchrotrons by its unique mirror system introduced to collect the synchrotron light from whole arc of the electron orbit. Unique feature of MIRRORCLE is described in this paper. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796573

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Among the 40 beamlines in operation at the European Synchrotron Radiation Facility, three beamlines are fully dedicated to X‐ray microscopy and micro‐spectroscopy techniques in the multi‐keV range. Offering a unique combination of non destructive analytical techniques which aim to satisfy the growing demand from experimental research fields such as medicine, geology, archaeology, earth, planetary and environmental sciences. Following a brief discussion on the strengths and weaknesses of X‐ray microscopy and spectro‐microscopy techniques in the 1–20keV range, characteristics of the beamlines are briefly described. Examples of applications are given in the reference list. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796574

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

With the aim of applying the phase‐contrast X‐ray imaging technique to biomedical imaging, we have been developing a large‐area imaging system based on a skew‐symmetric two‐crystal X‐ray interferometer. This latest of our imaging systems has a 60×30‐mm field of view and has been used to observe fine two‐ and three‐dimensional images of several biological samples by using a 17.7‐keV synchrotron X‐ray beam at the Photon Factory. In this paper, we give the outline of the imaging system and recent observational results of large biological samples. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796575

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Up to now, infrared synchrotron radiation (IRSR) has been recognized as a powerful light source because of its many excellent properties such as high brilliance, a small divergence angle of the light beam in the direction perpendicular to the plane of the ring, a continuous spectral distribution over the entire energy range from x‐ray to far‐infrared regions in addition to a well defined pulsed structure, and so on. There exist two different types of storage ring among the rings in the world. One is a compact ring such as UVSOR (Okazaki,Japan) with a rather small bending radius (2.2 m) of a diple magnet and the other a large scale of ring such as SPring‐8 (Harima,Japan) with a large radius (39.6 m). Both types of rings will open a new opportunities in the various fields of science because of its very high brilliance over conventional light sources. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796576

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Major advantages of a synchrotron is the energy tunability and very high brightness. These unique properties permit different types of spectroscopy which probe different physical and electronic properties to be performed. In this presentation, various experiments, from infrared (∼0.01 eV) to Compton scattering (125 keV), on ice and clathrate hydrates will be discussed. Using low‐temperature infrared spectroscopy, we have studied the mechanism for the novel iso‐structural phase transition of high pressure ice‐VIII. High resolution powder diffraction using high energy radiation was used to provide very accurate atom radial distribution functions for the characterization of the structural changes associated with the HDA to LDA ice transformation. Very high energy x‐ray was used to study the interactions between simple rare gas atoms and methane with the ice framework in clathrate hydrates. The “resonant scattering” of the guests with the ice vibrations was identified using x‐ray scattering and the specific role of the guest, in particular Kr in Kr hydrate was studied with the nuclear inelastic scattering technique. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796577

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Superior insulating performance is found for dense silicon dioxide ultra‐thin films (∼3 nm) grown by UV photo‐oxidation of silicon. Density profile obtained by glazing incidence x‐ray reflectivity shows that the high density (2.32 g/cm3) SiO2is formed on Si(100) surface at much lower temperature (<450 °C) than thermal oxidation, using 126 nm photons. The sharp and flat interface within 1–2 monolayers is revealed by high resolution transmission electron microscopy. The film density is strongly dependent on wavelength around 172–126 nm, suggesting that the specific excited species of oxygen is involved in the growth mechanism. Unique properties of photo‐oxidized silicon dioxide are related to the modified Si‐O network structure and ring statistics. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796578

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

The hard X‐ray microprobe provides an effective methodology for the non‐destructive analysis of inhomogeneous materials. Application of X‐ray absorption/fluroescence spectroscopy techniques (XANES and EXAFS) permits the speciation of the elements and yields information about the local structural environment. Microfocussed, monochromatic, tunable X‐rays allows examination of small areas of micrometer dimensions with spectroscopic procedures. Typically the materials which are presented are thick and cannot be altered for the experiment. This condition introduces difficulties which may compromise the results. Herein we discuss those difficulties and show that the system can yield reliable results in spite of the compromises. Some results are presented on the two iron meteorites we have examined. These specimens are representative of highly inhomogeneous materials and illustrate the difficulties encountered with compositional variations which may occur at sub‐millimeter dimensions and also illustrate the difficulties presented by the need to analyze components present at ppm concentration levels in a concentrated matrix. In these particular samples the major constituent is Fe which ranges from 90&percent; to 70&percent;, balanced by Ni which ranges from 10&percent; to 30&percent;. The critical diagnostic trace elements Ga and Ge which must also be analyzed are present at the 80 and 340 ppm level respectively. These diagnostic elements have been shown by EXAFS to be substitutionally placed in the matrix of the major element species in these meteorite samples. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796579

出版商:AIP    

年代:1904

数据来源: AIP

摘要:

Maximum values of the H‐bond energies and H‐bond pair volumes were determined from the OD‐stretching Raman contour of HDO in water using dispersion curves obtained from the temperature and pressure dependence of the intensities. The maximum H‐bond &Dgr;E value is 5,100 ± 500 cal/mol, and the maximum H‐bond pair &Dgr;V is 1.4 cm3/mol. A minimum in the volume dispersion curve indicates that some H‐bonds are strongly bent as the volume is decreased by pressure rise to ≈ 10 kbar at 28 ° C. Similar effects of H‐bond bending are observed from dispersion curves obtained from NaCl and NaBF4in water. The main effect on liquid water of isothermal pressure rise to 10 kbar is to form H‐bonds, both linear and bent, thus explaining freezing to ice VI. © 2004 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1796580

出版商:AIP    

年代:1904

数据来源: AIP