The triplet triplet absorption of pyrazine in the region 230–1900 nm is reported. (AIP)
No abstract is provided for this article.
No abstract is provided for this article.
The microstructure and magnetic properties of Fe_(87)Zr_7Si₄B₂ nanocrystalline alloys were studied by magnetization measurements and Mossbauer spectrometry over a wide temperature range. Three well resolved spectral components have been found and attributed to bcc-Fe grains (with almost pure iron structure), residual amorphous matrix enriched with solute elements and interfaces formed at the grain-matrix boundaries. It has been shown that, contrary to the expectation, during crystallization the atomic segregation occurs leading to the formation of primary bee-Fe grains and the partition of Si atoms into the residual amorphous matrix.
Comparison of spin sublevel population rates in pyrimidine and 5-methylpyrimidine suggests that the vibronic perturbation of 3B2 and/or 3A1 ππ* states by a higher-lying 3A2nπ* state plays an important role in S1 → T1 intersystem crossing of pyrimidine. The result also implies that the n+π*—n−π* splitting in pyrimidine is significantly smaller than the corresponding gap in pyrazine. The appearance of the 0.0 band in the τx spectrum indicates that the triplets state symmetry is lower tha C2v.
Viscoelastic behaviors of a Zr‐based glassy alloy in the glass transition region were investigated with uni‐axial compression tests. The transition between the linear and the nonlinear viscoelasticity was observed just as it was observed in other glassy materials. The transition is considered to be due to a structural change in the glassy structure. Using the relationship taken from experimental results between the steady‐state flow stress and their relaxation time at various temperatures, we make the steady‐state flow stress, which is named fictive stress, stand for the flow structure during deformation. Based on the hypothesis of the stress‐induced structure change and the concept of the fictive stress, we succeeded in demonstrating various characteristic viscoelastic behaviors. The model calculations agreed fairly well with the experimental results. The condition under which the transition occurs and the mechanism of the transition itself in various deformations of a Zr‐based glassy alloy were demonstrated by this model calculation.
Electricity and paper consumptions were estimated quantitatively for the cases where paper documents can be easily converted to electronic ones using combination of Fuji Xerox's multifunctional device of DocuCentre Color 450 and Fuji Xerox's software of DocuCentre Flow Service. For the typical case reduction of electricity and paper consumption as high as 15% and 0.79 t was shown to be attained.
No abstract is provided for this article.
The microstructural features of NdsFe76.sCosB6Cuo.sNbl nanocomposite magnet have been studied by a three-dimensional atom probe (JDAP) and transmission electron microscopy (TEM). The as-melt- spun microstructure is composed of a-Fe, NdzFe14B and a large fraction of intergranular amorphous phase. The annealed microstructure with optimum magnetic properties contains the same constituent phases as those in the as-quenched state, but the volume fraction of the NdzFelrB grains is increased by partial crystallization of the remaing amorphous phase. Nb and B are found to be enriched in the remaining amorphous phase. Unlike Fe3B/Nd2Fe14B nanocomposite, Cu additions are not effective in refining the grain size in this system. Index Termea-FelNd2Fe14B, amorphous, nanocompo- site magnet, exchange spring magnet
No abstract is provided for this article.
Zr70–76Al7–7.5Ni13–15Cu2Ag2–5 glassy alloys were prepared by melt-spinning with Zr contents up to 76 at.%, greatly exceeding the highest Zr content of 70 at.% previously reported for Zr-based glassy alloys exhibiting a calorimetric glass transition. The 70–72Zr and 74Zr alloys were also cast as bulk rods up to 1.5 mm in diameter with glass and [glass + β-Zr + ω-Zr] phases, respectively, by ejection copper-mold casting. The crystallization temperature and Vickers hardness Hv for the glassy ribbons decrease with increasing Zr content from 70 to 76 at.%. The glassy rods show high yield strength (σy) of 1225–1346 MPa, high fracture strength (σf) of 1497–1499 MPa, and large compressive plastic strain (εp) of 9.7–3.2% for the 70–72Zr alloys. Similarly, the 74Zr rod with [glass + β-Zr + ω-Zr] phases shows σy of 1325 MPa, σf of 1472 MPa, εp of 2.4%. The 76Zr thick ribbon with [glass + β-Zr + ω-Zr] phases shows, in tension, high σy of 890 MPa, σf of 988 MPa, and plastic elongation of 0.3%. The Zr-rich glassy ribbons crystallize, showing three exothermic peaks upon heating. The first-stage peak is due to the precipitation of icosahedral quasicrystal (IQ) for the 70–72Zr ribbons, and β-Zr + ω-Zr for the 74–76Zr ribbons. These annealing-induced mixed-phase ribbons with Zr content above 72 at.% exhibit good bending plasticity, even though their HV is about 41% higher than for the as-spun glassy ribbons. Similarly, the 70Zr bulk rod, with [glass + IQ] phases obtained by annealing, shows a distinct increase in σy and σf to 1485 and 1575 MPa, respectively, as well as εp of 0.6%. Thus, the plastic Zr-rich bulk rods with glass, [glass + IQ], and [glass + β-Zr + ω-Zr] phase mixtures are encouraging for the future development of a new type of high-strength structural material.
No abstract is provided for this article.
The mechanism of exciton migration in anthracene crystals was studied by measuring a rate constant, γ, for the bimolecular annihilation of exitons at various temperatures between 5°K and 250°K. Consequently, γ was found to be proportional to 1/√T. This is in accordance with the band model for the exciton motion. The present method for the study of the singlet-exciton migration, which is free from the trapping effect by impurity-induced lattice defects and from the host-guest interaction effect, is superior to the usual method using host-guest systems.
