Spectroscopy of η′ Mesic Nuclei with (p, d) Reaction

We are going to perform an inclusive spectroscopy experiment of η′ mesic nuclei with the ¹²C(p,d) reaction to study in-medium properties of the η′ meson. In nuclear medium, the η′ meson mass may be reduced due to partial restoration of chiral symmetry. In case of sufficiently large mass reduction and small absorption width of η′ at normal nuclear density, peak structures of η′ mesic states in ¹¹C will be observed near the η′ emission threshold even in an inclusive spectrum. The experiment will be carried out at GSI with proton beam supplied by SIS using FRS as a spectrometer. The detail of the experiment is described.     

Buffer-gas-assisted polarization spectroscopy of 6Li

We report on the demonstration of Doppler-free polarization spectroscopy of the D2 line of (6)Li atoms. Counterintuitively, the presence of an Ar buffer gas, in a certain pressure range, causes a drastic enhancement of the polarization rotation signal. The observed dependence of the signal amplitude on the Ar buffer pressure and the pump laser power is reproduced by calculations based on simple rate equations. We performed stable laser frequency locking using a dispersion signal obtained by polarization spectroscopy for laser cooling of (6)Li atoms.     

Optical band gap of semiconductive type II Si clathrate purified by centrifugation

The optical properties of Si clathrate, which is believed to have potential as a new Si-based material for optical devices, were investigated in this study. Si clathrates with type II structure (Na_xSi₁₃₆) with low Na content (x = 1.3, 2.0) were synthesized by thermal decomposition of NaSi. The synthesized samples were purified by centrifugation using a solution of CH₂Br₂–C₂Cl₄ to remove impurities. Using the obtained high purity samples (Na_1.3Si₁₃₆, 93 wt.%; Na_2.0Si₁₃₆, 90 wt.%), the optical absorption spectra of Na_xSi₁₃₆ were clarified, for the first time, from diffuse reflection measurements. The inclusion of Na in Si₁₃₆ was found to cause free carrier absorption in the infrared region but had little effect on the fundamental absorption edge found in the visible region.     

Size regulation by bandgap-controlled etching: Application to germanium nanoparticles

A germanium (Ge) nanoparticle surface was etched in an aqueous solution under monochromatic light irradiation in the infrared-to-ultraviolet region. Since the bandgap widened up to the photon energy of the irradiating light, the average size of the nanoparticles was controlled and the size distribution narrowed. The quantum size effect explained the correlation between the resulting bandgap energy and the final size. The etched nanoparticles showed blue-green or red-infrared photoluminescence (PL) after the surfaces were terminated with organic molecules or hydrogen atoms. The PL peak energy was independent of size, indicating PL was due to radiative recombination via localized states at the Ge core surface.     

Surface modification by vacuum annealing for field emission from heavily phosphorus-doped homoepitaxial (1 1 1) diamond

The relationship between field emission properties and C 1s core level shifts of heavily phosphorus-doped homoepitaxial (1 1 1) diamond is investigated as a function of annealing temperature in order to optimize surface carbon bonding configurations for device applications. A low field emission threshold voltage is observed from surfaces annealed at 800 °C for hydrogen-plasma treated surface, while a low field emission threshold voltage of wet-chemical oxidized surface is observed after annealing at 900 °C. The C 1s core level by X-ray photoelectron spectroscopy (XPS) showed a shoulder peak at 1 eV below the main peak over 800 and 900 °C annealing temperature for hydrogen-plasma treated and wet-chemical oxidized surfaces, respectively. When the shoulder peak intensity is less than 10% of the main peak intensity, lower threshold voltages are observed. This is due to the carbon-reconstruction which gives rise to a small positive electron affinity. By increasing annealing temperature, the shoulder peak ratios also increase, which indicates that a surface graphitization takes place. This leads to higher threshold voltages.     

Simultaneous determination of griseofulvin and 6-desmethylgriseofulvin in plasma by electron-capture gas chromatography

Two methods have been developed for the simultaneous determination of griseofulvin and its major metabolite 6-desmethylgriseofulvin in plasma using electron-capture gas chromatography. The first method was based on the quantitative reversion of the 6-desmethyl metabolite to griseofulvin by diazomethane. Plasma extract was chromatographed both before and after treatment with diazomethane, the former being the measure of griseofulvin and the latter representing the sum of the two compounds. In the second method, plasma extract was treated with diazobutane and griseofulvin and the butylated metabolite were separated by gas chromatography. The sensitivity for griseofulvin was 20 ng/ml by both methods and that for the metabolite was 20 ng/ml and 40 ng/ml by the first and the second method, respectively. The concentrations of the metabolite as well as griseofulvin were determined in dog and human plasma after oral administration of griseofulvin.     

Preparation and thermal behavior of poly-p-phenylene diacrylic acid dimethyl ester

The photopolymerization behavior of p-phenylene diacrylic acid dimethyl ester (p-PDA Me) crystal and the thermal behavior of the resultant poly-p-PDA Me were investigated. From the kinetic study of polymerization at various temperatures a topochemical process via a stepwise mechanism was observed. Continuous change from monomer to polymer crystals was demonstrated by x-ray diffraction pattern and DSC analysis. Crystallinity of the reacting phase was maintained at an extremely high degree during the polymerization process in support of monomer crystal lattice control. Thermal study on as-polymerized poly-p-PDA Me crystal confirmed that the thermal reaction was a polymer crystal lattice-controlled depolymerization, which was followed by miscellaneous processes that involved vaporization, sublimation, and deterioration of the oligomeric or monomeric units of p-PDA Me. Thermal stability was dependent on the molecular weight. All the results are compared with those of four-center-type photopolymerization in the crystalline state.     

Silica with Bimodal Pores for Solid Catalysts Prepared from Water Glass

The comparison of bimodal pore structures between silica gels prepared from silicon alkoxide and from water glass was performed based on the results of phase separation tendency, mesopore formation, and atomic scale observation using ²⁹Si NMR. Macropore structure could be controlled for both the raw material systems by inducing phase separation. Although the gelation in the water glass system is much faster than that in the silicon alkoxide system, there is little difference in the atomic scale structure, mesopore evolution during processing, and phase separation tendency. The results suggest that the obtained bimodal porous silica from water glass is essentially the same as that from silicon alkoxide. Because of the low cost of water glass, water-glass-derived bimodal porous silica is applicable to industrial use.     

Mechanochemical synthesis of rutile-type CrMO4 (M=V, Sb) and their solid solutions

Grinding a mixture of hydrous amorphous chromium oxide (Cr₂O₃·nH₂O), vanadium oxide (V₂O₅) and antimony oxide (Sb₂O₅) was conducted by using a planetary ball mill, to investigate their mechanochemical reactions to form chromium vanadium oxide (CrVO₄) and chromium antimony oxide (CrSbO₄). The synthesis reactions proceed with an increase in grinding periods of time. The ground samples consist of agglomerates with particle size of about ten nanometers. The synthesized CrVO₄ sample exhibits a rutile-type tetragonal crystal structure, which is a high pressure phase. Additionally, solid solutions, CrV_1−xSb_xO₄ (x=0∼1, Δx=0.25), have been synthesized mechanochemically from the mixtures of Cr₂O₃·nH₂O, V₂O₅ and Sb₂O₅.     

Determination of Stability Constants for Alkanol/α-Cyclodextrin Inclusion Complexes using the Surface Tension Method

The stability constants for the inclusion of alkanols with-cyclodextrin (-CD) in aqueous solutionhave been determined using the surface tension method. Dataanalyses assuming 1 : 1 stoichiometry were appliedto estimate the stability constants of thesecomplexes. The stability constants obtained using this methodwere in reasonable agreement with the corresponding values inthe literature. Chemically modified -CDs could not beused in this method because those CDs themselves have surfaceactivity. In addition, the relation between the stability constantsand the carbon number of alkanols is discussed.