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We report on the trapping of 14 keV photons in periods of 1.11–1.67 ps by the 12 4 0 backdiffraction in two- and multiplate silicon single-crystal cavities of a few hundred micrometer size. The formation of standing waves inside the cavities ensures better coherence for the x rays. We anticipate that the transmitted x rays through this type of cavities can be used as a quasicoherent x-ray source for probing the dynamic structures of solids, liquids, and biological substances. [ABSTRACT FROM AUTHOR]

Cubic phase yttrium-doped HfO2 (YDH) ultrathin films were grown on Si (111) substrates by molecular beam epitaxy. Thorough structural and morphological investigations by x-ray scattering and transmission electron microscopy reveal that the YDH thin films are epitaxially grown on the Si substrates with (111)YDH∥(111)Si and [101]YDH∥[110]Si. The interface between YDH and Si is atomistic sharp and free of interfacial layer. We have also determined the yttrium content of YDH films to be 19% by using anomalous x-ray diffraction (AXD) across Y k edge and angle resolved x-ray photoelectron spectroscopy (AR-XPS). The agreement between the AXD and AR-XPS results manifests that the incorporated Y atoms homogeneously substitute Hf atoms in the crystalline lattice and form a substitutional solid solution. [ABSTRACT FROM AUTHOR]

The authors report a general methodology for probing the depth profile of alloying extent and composition in bimetallic nanoparticles (NPs) by a combined in situ x-ray absorption spectroscopy (XAS) and electrochemical strategy. The XAS results of Pt-richcore–Ru-richshell NPs during methanol electro-oxidation revealed that the alloying extent of Pt (JPt) and Ru (JRu) is higher in the core region compared to those in the shell region. An average decrease in the JPt and JRu is observed when the cluster undergoes reduction. By controlling the cluster oxidation degree it is possible to probe the depth profile of the alloying extent in bimetallic NPs. [ABSTRACT FROM AUTHOR]

A generic x-ray diffraction method, using three-wave Bragg-surface diffraction, is developed to measure strains at the interface of molecular beam epitaxial Au/GaAs(001), where grazing-incidence diffraction cannot be applied due to the difference in refractive index between Au and GaAs. Changes in diffraction images of the surface reflection (1-13) of GaAs(006)/(1-13) three-wave Bragg-surface diffraction and the (-1-13) of GaAs(006)/(-1-13) at different azimuth and Bragg angles give the depth penetration of 2 Å resolution and variations of lattice constant, -49%, -27%, and 2%, along the surface normal [001] and in-plane directions [-1-10] and [1-10] within the depths of 18, 72, and 72 Å, respectively. [ABSTRACT FROM AUTHOR]

The electronic and atomic structures of quasi-one-dimensional blue bronze K0.3MoO3 were investigated by polarization-dependent O K-edge x-ray absorption near-edge structure (XANES) and Mo K-edge extended x-ray absorption fine structure (EXAFS) measurements at various temperature and applied voltages. The O K-edge XANES spectra suggest that the number of unoccupied O 2p–Mo 4d hybridized states increases and decreases with temperature, respectively, below and above a critical temperature of 180 K. The along b-axis electric current measurements show a threshold applied voltage, beyond which the current increases rapidly. The Mo K-edge EXAFS measurements show that the Mo–O bond lengths are insensitive to the temperature even beyond 180 K. [ABSTRACT FROM AUTHOR]

In this study, a distributed charge storage with GeO2 nanodots is demonstrated. The mean size and aerial density of the nanodots embedded in SiO2 are estimated to be about 5.5 nm and 4.3×1011 cm-2, respectively. The composition of the dots is also confirmed to be GeO2 by x-ray absorption near-edge structure analyses. A significant memory effect is observed through the electrical measurements. Under the low voltage operation of 5 V, the memory window is estimated to ∼0.45 V. Also, a physical model is proposed to demonstrate the charge storage effect through the interfacial traps of GeO2 nanodots. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The electronic and atomic structures of quasi-one-dimensional blue bronze K0.3MoO3 were investigated by polarization-dependent O K-edge x-ray absorption near-edge structure (XANES) and Mo K-edge extended x-ray absorption fine structure (EXAFS) measurements at various temperature and applied voltages. The O K-edge XANES spectra suggest that the number of unoccupied O 2p–Mo 4d hybridized states increases and decreases with temperature, respectively, below and above a critical temperature of 180 K. The along b-axis electric current measurements show a threshold applied voltage, beyond which the current increases rapidly. The Mo K-edge EXAFS measurements show that the Mo–O bond lengths are insensitive to the temperature even beyond 180 K. [ABSTRACT FROM AUTHOR]