Collinear fast atomic-beam laser spectroscopy at riken garis/igisol

We have constructed a fast atomic-beam collinear laser spectroscopy system connected to the on-line isotope separator facility GARIS/IGISOL at RIKEN. This system is potentially powerful in studying refractory elements. To test the system, an off-line collinear experiment was made on stable Hf isotopes produced by means of laser ablation technique. For production of radioactive Hf isotopes, the use of the inverse kinematics of a fusion reaction,⁹Be(¹⁶⁶Er,xn)^175-x Hf, was investigated. The radioactive isotope¹⁶⁹Hf was successfully extracted from GARIS/IGISOL and accelerated up to 30 keV.     

Analog vision chip for motion detection of an approaching object against a moving background based on the insect visual system

A network for motion detection of an approaching object without influence of the moving background was proposed based on the insect visual system. The two-dimensional array of the analog complementary metal oxide semiconductor (CMOS) circuits for extracting the edge signals of the approaching object without outputting those of the moving background was inserted at the first stage of the network. At the next stage, analog CMOS circuits for detection of approaching velocity and direction, which accept the extracted edge signals, were inserted based on the locust vision system. A chip of the proposed network was fabricated with the 1.2 mm CMOS process. It was clarified from the measured results and the simulation results with the simulation program with integrated circuit emphasis (SPICE) that the two-dimensional circuits of the first stage can only generate the signals of target edges. The measured results showed that the chip can detect the approaching velocity and direction of the target in the image which contains the moving background.     

Information amount and higher-order efficiency in estimation

By means of second-order asymptotic approximation, the paper clarifies the relationship between the Fisher information of first-order asymptotically efficient estimators and their decision-theoretic performance. It shows that if the estimators are modified so that they have the same asymptotic bias, the information amount can be connected with the risk based on convex loss functions in such a way that the greater information loss of an estimator implies its greater risk. The information loss of the maximum likelihood estimator is shown to be minimal in a general set-up. A multinomial model is used for illustration.     

The roles of molecular structure and effective optical symmetry in evolving dipolar chromophoric building blocks to potent octopolar nonlinear optical chromophores

A series of mono-, bis-, tris-, and tetrakis(porphinato)zinc(II) (PZn)-elaborated ruthenium(II) bis(terpyridine) (Ru) complexes have been synthesized in which an ethyne unit connects the macrocycle meso carbon atom to terpyridyl (tpy) 4-, 4'-, and 4'-positions. These supermolecular chromophores, based on the ruthenium(II) [5-(4'-ethynyl-(2,2';6',2'-terpyridinyl))-10,20-bis(2',6'-bis(3,3-dimethyl-1-butyloxy)phenyl)porphinato]zinc(II)-(2,2';6',2'-terpyridine)(2+) bis-hexafluorophosphate (RuPZn) archetype, evince strong mixing of the PZn-based oscillator strength with ruthenium terpyridyl charge resonance bands. Potentiometric and linear absorption spectroscopic data indicate that for structures in which multiple PZn moieties are linked via ethynes to a [Ru(tpy)(2)](2+) core, little electronic coupling is manifest between PZn units, regardless of whether they are located on the same or opposite tpy ligand. Congruent with these experiments, pump-probe transient absorption studies suggest that the individual RuPZn fragments of these structures exhibit, at best, only modest excited-state electronic interactions that derive from factors other than the dipole-dipole interactions of these strong oscillators; this approximate independent character of the component RuPZn oscillators enables fabrication of nonlinear optical (NLO) multipoles with extraordinary hyperpolarizabilities. Dynamic hyperpolarizability (β(λ)) values and depolarization ratios (ρ) were determined from hyper-Rayleigh light scattering (HRS) measurements carried out at an incident irradiation wavelength (λ(inc)) of 1300 nm. The depolarization ratio data provide an experimental measure of chromophore optical symmetry; appropriate coupling of multiple charge-transfer oscillators produces structures having enormous averaged hyperpolarizabilities (β(HRS) values), while evolving the effective chromophore symmetry from purely dipolar (e.g., Ru(tpy)[4-(Zn-porphyrin)ethynyl-tpy](PF(6))(2), β(HRS) = 1280 × 10(-30) esu, ρ = 3.8; Ru(tpy)[4'-(Zn-porphyrin)ethynyl-tpy](PF(6))(2), β(HRS) = 2100 × 10(-30) esu, ρ = 3.8) to octopolar (e.g., Ru[4,4'-bis(Zn-porphyrin)ethynyl-tpy](2)(PF(6))(2), β(HRS) = 1040 × 10(-30) esu, ρ = 1.46) via structural motifs that possess intermediate values of the depolarization ratio. The chromophore design roadmap provided herein gives rise to octopolar supermolecules that feature by far the largest off-diagonal octopolar first hyperpolarizability tensor components ever reported, with the effectively octopolar Ru[4,4'-bis(Zn-porphyrin)ethynyl-tpy](2)(PF(6))(2) possessing a β(HRS) value at 1300 nm more than a factor of 3 larger than that determined for any chromophore having octopolar symmetry examined to date. Because NLO octopoles possess omnidirectional NLO responses while circumventing the electrostatic interactions that drive bulk-phase centrosymmetry for NLO dipoles at high chromophore concentrations, the advent of octopolar NLO chromophores having vastly superior β(HRS) values at technologically important wavelengths will motivate new experimental approaches to achieve acentric order in both bulk-phase and thin film structures.     

Highly resolved scanning tunneling microscopy study of Si(0 0 1) surfaces flattened in aqueous environment

A surface preparation method with fine SiO₂ particles in water is developed to flatten Si(0 0 1) surfaces on the nanometer scale. The flattening performance of Si(0 0 1) surfaces after the surface preparation method is investigated by scanning tunneling microscopy. The observed surface is so flat that 95% of the view area (100 × 100 nm²) is composed of only three atomic layers, namely, one dominant layer occupying 50% of the entire area and two adjacent layers. Furthermore, a magnified image shows the outermost Si atoms regularly distributed along the 〈1 1 0〉 direction on terraces.     

Crystal structure of copper(II) complex with N,N-bis(2-benzimidazolylmethyl)benzylamine

The copper(II) complex with N,N-bis(2-benzimidazolylmethyl)benzylamine has been synthesized and its crystal structure was determined by X-ray diffraction methods.     

Preliminary communicationPalladium-catalyzed carboxylation of aromatic compounds with carbon dioxide

Carbon dioxide has been found to react with aromatic compounds such as benzene, anisole, furane, and thiophene to give aromatic acids in modest yields with palladium(II) salts as catalysts. The addition of t-BuOOH increases the yield.     

Photon-echo profile in the ultrashort time region for pentacene molecules in crystals

Photon-echo behavior in the ultrashort time region is studied for pentacene molecules in p-terphenyl crystals at 1.7 K by means of the accumulated three-pulse echo. We show highly resolved echo spectra with a parameter of time separation and also time behavior of echo intensity as a function of pulse separation measured at various frequencies near the peak position of the absorption line of the S₀–S₁ transition. We demonstrate various features of echo profile in both time and frequency domains, which are dependent on the time region of observation.     

Role of hydroxyl groups in the stereochemistry of hydrogen transfer from chiral NAD(P)H model to carbonyl

Asymmetric reduction of α-ketoester with a chiral dihydronicotinamide was significantly affected by chiral aromatic additives, capable of exerting an attractive interaction with dihydropyridine ring, which was further consolidated through with magnesium.