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The dependence of chemical composition on the average sizes of subnanometer-scale intrinsic structural open spaces surrounded by glass random networks in two-component silica-based glasses was investigated systematically using positronium (Ps) confined in the open spaces. The average sizes of the open spaces for SiO2-B2O3 and SiO2-GeO2 glasses are only slightly dependent on the chemical compositions because the B2O3 and GeO2 are glass network formers that are incorporated into the glass network of the base SiO2. However, the open space sizes for all SiO2-R2O (R=Li, Na, K) glasses, where R2O is a glass network modifier that occupies the open spaces, decrease rapidly with an increase in the R2O concentration. Despite the large difference in the ionic radii of the alkali metal (R) atoms, the open space sizes decrease similarly for all the alkali metal atoms studied. This dependence of the chemical composition on the open space sizes in SiO2-R2O observed by Ps shows that the alkali metal atoms do not randomly occupy the structural open spaces, but filling of the open spaces by R2O proceeds selectively from the larger to the smaller open spaces as the R2O concentrations are increased. [ABSTRACT FROM AUTHOR]

Quantum mechanical treatment of a light wave that propagates through an absorptive medium is presented. Unlike a phenomenological beam-splitter model conventionally employed to describe a traveling light in a lossy medium, the time evolution of the field operator is derived using the Heisenberg equation with the Hamiltonian for a physical system, where the light wave interacts with an ensemble of two-level systems in a medium. Using the obtained time-evolved field operators, the mean values and variances of the light amplitude and the photon number are evaluated. The results are in agreement with those obtained in the beam-splitter model, giving a logical theoretical basis for the phenomenological beam-splitter model. [ABSTRACT FROM AUTHOR]

Presents a study that measured the time dependence of the secondary ion intensity in secondary ion mass spectroscopy analysis of insulating films. Schematic diagram of the process on the reduction of surface charging and its equivalent circuits; Relation between the ion intensity suppression ratio and the film thickness.

Abstract: We used reflectance difference spectroscopy (RDS) and surface differential reflectance spectroscopy (SDRS) to investigate the molecular orientation of ultrathin α-sexithiophene (α-6T) films on four passivated Si(100)-(2×1) surfaces, oxidized Si(001), water-adsorbed Si(001), hydrogen-adsorbed Si(001) and ethylene-adsorbed Si(001), in order to study the substrate dependence of the molecular orientation of isolated molecules and molecules located in islands or films. Strong in-plane anisotropy was observed on ethylene-adsorbed Si(001) even at 5nm film thickness, which was not the case for the other substrates. [Copyright &y& Elsevier]

Abstract: KamLAND is a reactor neutrino oscillation experiment with a very long baseline. This experiment successfully measured oscillation phenomena of reactor antineutrinos coming mainly from 53 reactors in Japan. In order to extract the results, it is necessary to accurately calculate time-dependent antineutrino spectra from all the reactors. A simple model of reactor cores and code implementing it were developed for this purpose. This paper describes the model of the reactor cores used in the KamLAND reactor analysis. [Copyright &y& Elsevier]

Jahn–Teller (JT) distortion of the diamagnetic neutral divacancy (V20) in Si is studied by positron annihilation spectroscopy. Based on the anisotropy of electron momentum distribution around the divacancies obtained by two-dimensional angular correlation of positron annihilation radiation (2D-ACAR) technique, the preferred alignment of the divacancy in a specimen by compressing uniaxial stress along the [0 1 1] axis is detected. The direction of the alignment evidences the pairing JT distortion rather than the resonant bonding distortion, which is similar to the distortion in the singly negative divacancy (V2−). [Copyright &y& Elsevier]

We have measured the Raman and cathodoluminescence (CL) spectra of ZnO nanoparticles with different crystallite sizes. The Raman spectra show that the frequency of the E2 (high) phonon in these nanoparticles, which is initially high, decreases with the crystallite size, while its linewidth increases. This result is explained by the size effect. The CL spectra show that the relative intensity ratio of the CL peak at around 500–600 nm to the band-edge CL peak at approximately 360 nm drastically increases as the crystallite size decreases. We use the surface recombination model to explain this result. According to this model, the relative intensity ratio increases because of an increase in the concentration of deep levels on the surface of the crystallites and/or an increase in the free-carrier concentration. [ABSTRACT FROM AUTHOR]

The transition temperatures between high- and low-spin states of the assembled spin-crossover complexes, Fe(NCX)2(bpa)2(guest) (X = S, Se, BH3; bpa = 1,2-bis(4-pyridyl)ethane; guest = biphenyl, 2-nitrobiphenyl, diphenylmethane, or 1,4-dichlorobenzene), were compared with the Mössbauer parameters. The transition temperature increases when the QS value of FeII high-spin state becomes small. The transition temperature also increases by changing the anion from NCS to NCSe and then to NCBH3. [ABSTRACT FROM AUTHOR]

This study provides an overview of the recent experiments employing methods that analyse, systematically, series of analytical spectra acquired either in nanobeam mode in a transmission electron microscope or using elemental mapping in a scanning transmission electron microscope. A general framework is presented that describes how best to analyse series of such spectra to quantify the areal density of atoms contained within a very thin layer of a matrix material, as, for example, appropriate to measure grain boundary segregation. We show that a systematic quantification of spectra as a function of area size illuminated by the electron beam eliminates the large systematic errors inherent in simpler approaches based on spatial difference methods, integration of compositional profiles acquired with highly focused nanoprobes or simple repeats of such measurements. Our method has been successfully applied to study dopant segregation to inversion domain boundaries in ZnO, to quantify the thicknesses of sub-nm thin layers during epitaxial growth by molecular beam epitaxy of (In)GaAs and to prove the absence of gettering of dopants at Σ = 3{111} grain boundaries in Si, with a precision <1 atom/nm in all these cases. [ABSTRACT FROM AUTHOR]

Abstract: We present a microstructural study of a surveillance test specimen from a reactor pressure vessel steel of a Russian-type nuclear reactor after neutron irradiation, post-irradiation annealing and re-irradiation, using atom probe tomography (APT) and positron annihilation spectroscopy (PAS). The APT results showed the formation of Cu-rich solute nano-clusters (CRCs) during the initial irradiation and their subsequent coarsening during annealing. After re-irradiation, new CRCs have been observed. The irradiation-hardening almost recovered during annealing. However, by re-irradiation, hardening comparable to that by the initial irradiation was observed. The hardening due to the CRCs formed during the initial irradiation, estimated using the Russell–Brown model, was almost the same as that observed. However, the estimated hardening after the re-irradiation was about half of the measured one. The other hardening is attributed to the newly formed MDs by the re-irradiation, which was evidenced by PAS. [Copyright &y& Elsevier]

Resonance modes corresponding to a spin-soliton resonance have been found in the electron spin resonance spectra of [Cr(CN)6][Mn(S)-pnH-(H2O)]H2O two-dimensional (2D) chiral single crystals and [Mn{(R/S)-pn}]2[Mn{(R/S)-pn}2(H2O)][Cr(CN)6]2 chiral single crystals with a 3D magnetic order. It is also established that the chiral crystals of both types exhibit a spin-wave resonance analogous to the excitation of standing spin waves in thin magnetic films. At the same time, racemic crystals of the first type do not exhibit spin-soliton resonance. The entire body of experimental data indicates that the chirality of crystals influences the spin excitations (standing spin waves and solitons) in these media. [ABSTRACT FROM AUTHOR]

Abstract: We studied on the photoluminescence (PL) properties of Er in tensile-strained Si on a SiGe layer (Si:Er:O/SiGe) and compressively strained SiGe on a Si layer (SiGe:Er:O/Si) grown by molecular beam epitaxy (MBE). Er-related luminescence was observed around 1.54μm in both tensile- and compressively strained samples. The PL intensities of strained Si:Er:O/SiGe and SiGe:Er:O/Si samples were much stronger than those of unstrained Si:Er:O/Si samples. Moreover, intensive luminescence was observed in strained samples with low Er concentrations far below 1018 cm−3. The PL spectra of Si:Er:O/SiGe samples were broader than those of unstrained Si:Er:O/Si samples. On the other hand, no significant differences in the width between SiGe:Er:O/Si and unstrained samples were observed. These differences in the PL intensity between strained and unstrained samples strongly suggest that the optical activation of Er in Si and SiGe can be enhanced by the presence of strain. [Copyright &y& Elsevier]

Assembled complex, Fe(bpa)2(NCX)2 (bpa=1,2-bis(4-pyridyl)ethane; X=S, Se, BH3) enclathrated diphenylmethane. The skeletons were interpenetrating structures for NCS and NCSe complexes, while 2D grid structure was obtained for NCBH3 complex. The assembled iron complexes showed spin-crossover phenomena by enclathrating diphenylmethane. The ratio of spin transition and the transition temperature depended on the assembled structure. [ABSTRACT FROM AUTHOR]

The variations in the magnetic resonance spectra accompanying the transition from the paramagnetic to ferrimagnetic state in [{Cr(CN)6}{Mn(S)-pnH-(H2O)}] · H2O orthorhombic chiral molecular crystals were studied. The dependence of the EPR linewidth on temperature in the proximity of the transition point TC = 38 K argues for the two-dimensional character of spin ordering. The spin resonance line was found to undergo exchange narrowing at T > TC. The ferrimagnetic phase has an easy magnetization axis coinciding with the a crystallographic axis. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

We studied on the effect of the strain on photoluminescence (PL) properties of Er-doped Si on a SiGe layer (Si:Er:O/SiGe) and Er-doped SiGe on a Si layer (SiGe:Er:O/Si) grown by molecular beam epitaxy. Er-related luminescence was observed around 1.54 μm in all the samples. The PL spectra of the Si:Er:O/SiGe samples are much broader and stronger than those of the Si:Er:O/Si samples prepared as reference. Moreover, the intensive luminescence was observed in the Si:Er:O/SiGe sample that had much lower Er concentration of about 2.5×1016 cm−3. On the other hand, the significant differences in the PL spectra between the SiGe:Er:O/Si and Si:Er:O/Si samples were not observed. These indicate that the tensile strained Si enhances the optical activation of Er. [Copyright &y& Elsevier]

A molecule-based magnet [Cr(CN)6][Mn(R/S)-pnH(H2O)](H2O) (termed R/S-GN) is a chiral crystal without an inversion center and mirror reflection, and its structural network is constructed using a chiral ligand diaminopropane (R/S)-pn. In S-GN, multiple spectra of ESR were observed below the magnetic ordering temperature by Morgunov et al. [Phys. Rev. B 77, 184419 (2008)]. They concluded that the phenomenon at the high field side occurred because the incommensurate magnetic structure resulted in a length-controllable superlattice of domain walls (the so-called chiral soliton lattice, CSL) under a dc magnetic field H applied perpendicular to the magnetic chiral axis. However, there multiple spectra were observed even for H nearly parallel to the chiral axis, a-axis, and their interpretation is unreasonable. Thus, we conducted an X-band electron spin resonance (ESR) measurement of R-GN under conditions similar to those of their experiment and performed Fourier spectrum analyses for the data of R-GN as an approach of physical characterization. By using two Lorentz spectra, the main ESR spectra for H // a were reproduced, and furthermore two prominent periodic modes were found by spectrum analyses based on Fourier transform. Two characteristic periods, p1 and p2 (