CO2-laser isotope separation of tritium with pentafluoroethane-T (C2TF5)

Isotope separation of tritium by CO₂ laser-induced multiphoton dissociation (MPD) of C₂TF₅ is reported for the first time. The MPD spectrum obtained for C₂TF₅ comprised a broad peak at about 940 cm^–1 where C₂HF₅ was nearly transparent. The unimolecular dissociation of C₂TF₅ was induced with much lower laser fluence than that for CTF₃, another working molecule we proposed for laser isotope separation of tritium. The mechanisms and kinetics of the dissociation of C₂TF₅ and C₂HF₅ were investigated under various experimental conditions: laser frequency, pulse energy, pulse duration, tritium concentration, sample pressure, buffer gas pressure and irradiation geometry. Single-step separation factors exceeding 500 were achieved with the most efficientP(20) line in 00^o–10^o0 transition at 944.2 cm^–1.     

Elastic and inelastic scattering of vector polarized deuterons from even samarium isotopes at 56 MeV

Differential cross sections and vector analyzing powers of deuteron elastic and inelastic scattering have been measured at 56 MeV over the whole range of the even samarium isotopes. Comprehensive analyses were performed with the optical model and the coupled-channels formalism. In the optical model analysis, calculations with a global parameter set could reproduce the experimental data only for the vibrational nuclei. The strong coupling approximation was applied assuming the ^{144, 148, 150}Sm to be harmonic vibrators and the ^152,154Sm symmetric rotators. The 2^λ (λ = 2, 3, 4, 6) pole deformation parameters were deduced from a systematic coupled-channels analysis. The transition strengths were extracted from the deformed optical potentials and compared with the corresponding electromagnetic ones. The transition rates for the rotational nuclei agreed with the electro-magnetic ones, but those for the vibrational nuclei gave the systematically smaller values. The latter fact was attributed to the difference between the proton and neutron transition matrix elements near the neutron-closed-shell nuclei. The ratios of the two matrix elements were obtained.     

Eigenvalue inequalities for products of matrix exponentials

Motivated by models from stochastic population biology and statistical mechanics, we proved new inequalities of the form $\text{(1) ?(e}{}^{\mathrm{A}}\text{e}{}^{\mathrm{B}}\text{)??(e}{}^{\mathrm{A+B}}\text{)}$, where A and B are n × n complex matrices, 1<n<∞, and ? is a real-valued continuous function of the eigenvalues of its matrix argument. For example, if A is essentially nonnegative, B is diagonal real, and ? is the spectral radius, then (1) holds; if in addition A is irreducible and B has at least two different diagonal elements, then the inequality (1) is strict. The proof uses Kingman's theorem on the log-convexity of the spectral radius, Lie's product formula, and perturbation theory. We conclude with conjectures.     

Stereo- and regio-controlled aldol synthesis

Treatment of (Z)-trimethylsilyl enol ethers with dibutylboryl trifluoromethanesulfonate followed by removal of trimethylsilyl triflate generated and addition of aldehydes affords the corresponding erythro aldols with almost complete stereo- and regio-selectivities.     

Ferroelectric characteristics of silicate-bound Bi4Ti3O12 thin films

40-nm-thick Bi₄Ti₃O₁₂ films have been deposited by spin coating with a hybrid precursor solution of bismuth-2-ethylhexanoate, titanium tetraisopropoxide and tetraethysilicate. The 500 °C-annealed thin film consists of Bi₄Ti₃O₁₂ grains bound by ultra-thin amorphous silicate layers. The film shows a high degree of crystallinity with random orientation and exhibits a structure-dependent propeller-like P–V hysteresis loop. The ultra-thin layer of amorphous silicate is found to have multiple functions of binder, compositional buffer and insulator, which results in an improvement of the electrical properties of the Bi₄Ti₃O₁₂-Bi₂O₃×SiO₂ thin films. PACS 77.84.-s; 68.37.-d; 81.15.-z