Development of a high‐resolution confocal micro‐XRF instrument equipped with a vacuum chamber

A confocal micro‐X‐ray fluorescence (micro‐XRF) instrument equipped with a vacuum chamber was newly developed. The instrument is operated under a vacuum condition to reduce the absorption of XRF in the atmosphere. Thin metal layers were developed to evaluate the confocal volume, corresponding to depth resolution. A set of thin metal layers (Al, Ti, Cr, Fe, Ni, Cu, Zr, Mo, and Au) was prepared by a magnetron sputtering technique. The depth resolutions of the new instrument were varied from 56.0 to 10.9 µm for an energy range from 1.4 to 17.4 keV, respectively. The lower limit of detection (LLD) was estimated by comparison with a glass standard reference material NIST SRM 621). The LLDs obtained by a conventional micro‐XRF were compared with the LLDs obtained by a confocal micro‐XRF instrument. The LLDs were improved in the measurement under confocal configuration because of the reduction of background intensity. Finally, layered materials related to forensic investigation were measured. The confocal micro‐XRF instrument was able to nondestructively obtain the distribution of light elements that cannot be detected by measurement in air. Copyright © 2013 John Wiley & Sons, Ltd.     

Experimental Study of the Interaction between Two Lambda Hyperons

The knowledge of ${\Lambda{-}\Lambda}$ interaction is quite limited. At present, only Nagara event gives a definite information for its interaction among nine samples of double hypernucleus in the world. To obtain nuclear mass dependence of the interaction with one thousand double hypernuclei, a system for fully automated scanning of ${\Xi^-}$ hyperons was developed by the success of precise position alignment (1 μm) of nuclear emulsion plates. Production and decay of double hypernuclei have typical topologies with three vertices. The development of a system to search for such topologies in overall emulsion is ongoing.     

Transition‐Metal‐Mediated Cleavage of Fluoro‐Silanes under Mild Conditions

Si?F bond cleavage of fluoro‐silanes was achieved by transition‐metal complexes under mild and neutral conditions. The Iridium‐hydride complex [Ir(H)(CO)(PPh₃)₃] was found to readily break the Si?F bond of the diphosphine‐ difluorosilane {(o‐Ph₂P)C₆H₄}₂Si(F)₂ to afford a silyl complex [{[o‐(iPh₂P)C₆H₄]₂(F)Si}Ir(CO)(PPh₃)] and HF. Density functional theory calculations disclose a reaction mechanism in which a hypervalent silicon species with a dative Ir→Si interaction plays a crucial role. The Ir→Si interaction changes the character of the H on the Ir from hydridic to protic, and makes the F on Si more anionic, leading to the formation of H^δ+???F^δ? interaction. Then the Si?F and Ir?H bonds are readily broken to afford the silyl complex and HF through σ‐bond metathesis. Furthermore, the analogous rhodium complex [Rh(H)(CO)(PPh₃)₃] was found to promote the cleavage of the Si?F bond of the triphosphine‐monofluorosilane {(o‐Ph₂P)C₆H₄}₃Si(F) even at ambient temperature.     

Research on Liebeskind-Srogl coupling/intramolecular Diels-Alder reaction cascade

The Liebeskind-Srogl coupling/intramolecular Diels-Alder (IMDA) reaction cascade that stereoselectively affords a tricarbocyclic compound with a trans–trans-cis fused ring system including an all-carbon quaternary stereogenic center at the ring junction is described. The cascade reactions proceed quickly and stereoselectively afford the products within 2?h at room temperature in the presence of a suitable thioester. The developed protocol as well as the prepared chiral compounds are useful for the enantioselective total synthesis of terpenoids with the trans–trans-cis fused ring system.     

Timing jitter of solitons compressed in dispersion-decreasing fibers

It is shown that timing jitter owing to the Gordon-Haus (G-H) effect of solitons that are compressed adiabatically in dispersion-decreasing fibers (DDF's) is approximately determined by total dispersion and initial conditions, which are independent of compression dynamics. As a result the established theory for G-H jitter is still applicable. Timing jitter near the levels predicted by theory is observed in pulses from a regeneratively mode-locked fiber laser compressed in a DDF.     

Calorimetric study of molecular superconductor κ-(BEDT-TTF)<Subscript>2</Subscript>Ag(CN)<Subscript>2</Subscript>H<Subscript>2</Subscript>O which contains water in the anion layers

Thermodynamic investigation of an organic superconductor κ-(BEDT-TTF)₂Ag(CN)₂H₂O in which the BEDT-TTF dimers are arranged in the κ-type structure in the donor layers is performed by the relaxation calorimetric technique at low temperatures and under magnetic fields. A thermal anomaly related to the superconductive phase transition was observed at 5 K. The existence of residual γ^* in the superconductive state is about 18% of the normal state γ value, which is larger than those of κ-(BEDT-TTF)₂Cu(NCS)₂, and κ-(BEDT-TTF)₂Cu[N(CN)₂]Br salt. The lattice heat capacity reflected on the β-term in the low-temperature heat capacity was found to be affected by the cooling rate. The disorder produced in the network structure constructed by hydrogen bond in the insulating layer is considered to give low-energy phonon excitations reflected in the heat capacity.     

Photoluminescent properties and molecular structures of [NaphAu(PPh(3))] and [mu-Naph {Au(PPh(3))}(2)] ClO(4) (Naph = 2-naphthyl)

The complexes [NaphAu(PPh(3))], and [mu-Naph{Au(PPh(3))}(2)]ClO(4), having the Au-C (aromatic) bond have been synthesized and characterized. The unique structure of with two gold atoms bridged by a naphthyl group has been determined by X-ray crystallography. The intramolecular Au-Au separation in is 2.7731(4) A. Upon excitation at 266 nm, both complexes display intraligand phosphorescence at room temperature in solution and in solid state.     

Stir bar sorptive extraction and thermal desorption-gas chromatography-mass spectrometry for trace analysis of triclosan in water sample

A simple and highly sensitive method called stir bar sorptive extraction (SBSE) and thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS), which is used for the determination of trace amounts of 5-chloro-2-(2,4-dichlorophenoxy)phenol (triclosan) in river water samples, is described. A stir bar coated with polydimethylsiloxane (PDMS) is added to a 10mL water sample and stirring is carried out for 120min at room temperature (25 degrees C) in a vial. Then, the PDMS stir bar is subjected to TD-GC-MS. The detection limit of triclosan is 5ngL(-1) (ppt). The method shows linearity over the calibration range (0.02-20mugL(-1)) and the correlation coefficient is higher than 0.997 for triclosan standard solution. The recovery of triclosan in river water samples ranges from 91.9 to 108.3% (RSD: 4.0-7.0%). This simple, accurate, sensitive, and selective analytical method may be used in the determination of trace amounts of triclosan in river water samples.