Improvement of color rendering index of BGYR laser illuminants

Optical Review - Laser-driven phosphor conversion (PC)-type white light sources are receiving a great deal of attention in next-generation high-intensity lighting and display technologies. Laser...     

Spectral simulation for infrared surface electromagnetic wave spectroscopy

Infrared surface electromagnetic wave spectra, which are obtained by the Otto and Kretschmann configurations, are calculated by the Fresnel formula of stratified layers. The calculated reflectivity is plotted as a function of incidence angle, air gap thickness, metal layer thickness, and wavenumbers. From these calculations, optimum experimental variables for both configurations are predicted in the infrared region. At the optimum angle of incidence, the z-component of the electric field intensity was found to be maximum at the surface of silver. The calculated SEW spectra of a PVAc film on silver show a large value of ΔR and a strong frequency dependence. The Otto configuration has advantages in the mid-infrared region.     

Improvement of Cu2ZnSnS4 thin film morphology using Cu–Zn–Sn–O precursor fabricated by sputtering

The new precursor of Cu–Zn–Sn–O (CZTO) was proposed for Cu₂ZnSnS₄ (CZTS) thin film fabrication to improve film morphology. The CZTS thin film grown from Cu–Zn–Sn (CZT) precursors has many bumps. We deposited CZTO precursors on Mo/soda-lime glass (SLG) substrates by RF sputtering using a CZT (Cu:Zn:Sn = 2:1:1) target in Ar and O₂ atmosphere at various O₂ partial pressures (0%, 5%, 17% and 20%). Subsequently, the CZTO precursors were sulfurized in Ar and S atmosphere to fabricate CZTS thin films. The CZTO precursors were amorphous. The morphology of the CZTS thin films was improved by the CZTO precursors. All of the CZTS films fabricated in this study had the same crystal structure. Composition analysis revealed that 50% of O were detected in the CZTO precursor, but O was not detected after sulfurizing process, indicating that O was substituted by S. The CZTS thin film from the CZTO precursor fabricated at O₂ partial pressure of 20% had similar composition for solar cell absorber.     

Tributylstannyl radical-catalyzed reaction of 1,2,3-selenadiazoles with olefins or dienes

It was found that the reaction of 1,2,3-selenadiazoles derived from cyclic ketones with olefins or dienes was markedly promoted by a catalytic amount of tributylstannyl radical, which was generated in situ from tributylstannyl hydride or allyltributylstannane and AIBN, to give the corresponding dihydroselenophenes in moderate to good yields. In contrast, when 1,2,3-selenadiazoles prepared from linear and aromatic ketones were used as substrates, the same reaction did not take place, and alkynes were formed as the sole product.     

Studies of the decay B+/- -->D(CP)K+/-

We report studies of the Cabibbo-suppressed decay B+/--->D(CP)K+/-, where D(CP) denotes CP eigenstates of the D0-D0; system. The analysis is based on a 29.1 fb(-1) sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) storage ring. We measure ratios of branching fractions, relative to Cabibbo-favored B+/--->D(CP)pi(+/-), of B(B--->D1K-)/B(B--->D1pi(-))=0.125+/-0.036+/-0.010 and B(B--->D2K-)/B(B--->D2pi(-))=0.119+/-0.028+/-0.006; the index 1 (2) denotes the CP=+1 (-1) eigenstate. We also extract the partial rate asymmetries for B+/--->D(CP)K+/-, finding A(1)=0.29+/-0.26+/-0.05 and A(2)=-0.22+/-0.24+/-0.04.     

Observation of rho/omega meson modification in nuclear matter

We measured the invariant mass spectra of electron-positron pairs in the target rapidity region of 12-GeV p+A reactions. We have observed a significant difference in the mass spectra below the omega meson between p+C and p+Cu interactions. This difference indicates that the spectral shape of mesons is modified at normal nuclear-matter density.     

Extension of measurable range of film dosimetry by a low energy X-ray absorption method

The availability of an X-ray absorption technique employing a very low power X-ray tube was examined to extend measurable range for photographic film dosimetry. The X-ray tube having titanium target was operated at 8 kV and 0.2 microA to emit Ti KX-rays of moderate intensity. The degree of the Ti KX-ray absorption, defined as similar to photographic density, was measured for the two kinds of badge film, Fuji gamma-ray badge film and Kodak personal monitoring film, type 2 exposed for 60Co or 137Cs gamma-rays and developed by the respective standard procedures. The experimental results show that the dosimetric range of 0.01-100 R for the Fuji film and 0.03-1,000 R for the Kodak film may be easily measured by 1 minute counting with the relative statistical error (sigma) of 10%.     

Interplay between a homogeneous magnetic field and an antiferromagnetic field in one-dimensional superconductors

Mean-field theory applied to superconductors with one-dimensional band in the presence of both the homogeneous magnetic field H₀ and the antiferromagnetic field H_Q, the second-order phase transition temperature is investigated for the arbitrary angle θ between H₀ and H_Q. It is found that the remarkable superconducting region in the case of θ = 0 is retained only for small θ and that the spatially dependent order parameter coexists with the spatially uniform order parameter except for θ = τ/2.