Satsuo Kamata

Copper(II)-selective membrane electrodes based on o-xylylene bis(dithiocarbamates) as neutral carriers

o-Xylylene bis(diisobutyl- and methyloctadecyl-dithiocarbamate) were synthesised and used as neutral carriers in membrane electrodes to improve the selectivity for Cu2+. The electrodes based on these ionophores, with o-nitrophenyl octyl ether as a plasticising solvent mediator and potassium tetrakis-(p-chlorophenyl)borate as an anion excluder, exhibit a linearity range of 10–1–10–6Mand have a Nernstian slope of 28–29 mV per decade at 25 °C. The highly selective electrode based on o-xylylene bis(diisobutyldithiocarbamate) rejected the interference of alkali, alkaline earth and transition metal cations by a factor in the range 102–104 and showed a high selectivity for Cu2+ even in chloride and bromide media. The properties of the electrodes are discussed and also compared with those of o-xylylene bis(diethyldithiocarbamate) under similar measurement conditions.

Copper(II)-selective electrodes based on macrocyclic polythiaethers

PVC membrane electrodes that are selective and sensitive to copper(II) have been developed. The best electrode, based on 13,14-benzo-1,5-tetrathiacyclopentadecane and 2-nitrophenyl octyl ether solvent mediator with a potassium tetrakis(p-chlorophenyl)borate anion excluder, exhibits a linear response in the range 10–1–10–6M over the pH range 2.9–6.7 and has a Nernstian slope of 28–29 mV per decade at 25 °C. The response time is 10 s.

Electron impact dissociation of molecular hydrogen and deuterium: Translational energy distribution of atomic hydrogen and deuterium (n = 3,4,5)

Abstract The translational energy distributions of the excited hydrogen and deuterium atoms ( n = 3,5) produced in e-H 2 and e-D 2 collisions have been obtained from an analysis of the Doppler line shapes of their Balmer lines. The distributions of H*(D*)( n = 3,5) are qualitatively identical with those of H*(D*)( n = 4) and consist of three major components; but, their relative intensities are different. Thus, it can be concluded that dissociative excitation of hydrogen leading to the formation of the hydrogen atom ( n = 3,4,5) proceeds in similar processes. Important intermediate excited states are Rydberg states converging to the 2 Σ g + (1sσ g ) and 2 Σ u + (2pσ u ) states of H 2 + (D 2 + ). The contribution of the low-lying doubly-excited Rydberg states also exists; however, this is smaller for the heavier atom and for the smaller principal quantum number. Comparison of translational energy distributions between H*(D*) ( n = 3,4,5) and H + (D + ) justifies an extension of the core-ion model of molecular dissociation for the formation of low-Rydber emissive atoms.

Electron impact dissociation of molecular Hydrogen and Deuterium: Isotope effect on the emission cross section of H* AND D* (n=3,4,5)

Abstract The Balmer a B , y lines of the excited hydrogen atoms ( n =3,4,5) produced in e-H 2 and D 2 collisions have beeen measured at high resolutions. The isotope effects for the formation of the slow and the fast groups of excited hydrogen and deuterium atoms are obtained separately from an analysis of the Doppler line shapes. The observed values of σ D / σ H for the slow group are 0.68±0.10, 0.49 ±0.09 and 0.25 ±0.06 for n = 3. 4 and 5, respectively, and are independent of the electron energy (25- 100 eV). These results indicate that the wider Franck-Condon region and the smaller reduced mass of H 2 , are favorable for dissociation, and that the contribution of predissociation becomes small with increasing n . An isotope effect for the fast group seems to be present. The emission cross sections and their electron energy dependence have been estimated for both groups.

Preparation and mechanical properties of long alumina fiber/alumina matrix composites

Abstract Alumina long fiber (22 vol%)/alumina matrix composites were formed by infiltration of aqueous alumina suspensions into alumina fiber-sheets and sintered in air or in vacuum at 1000–1400 °C. The fracture behaviour and strength of the composites were interpreted in relation to the following factors: strength of the alumina matrix, sintering between alumina fibers and matrix at the interfaces, coating effect of inert material over the surface of alumina fibers and degree of adhesion of interfaces.

Potentiometric flow analysis device using membrane-coated carbon rod ion-selective electrode detectors

Abstract A flow-through analysis system that utilizess a membrane-coated carbon rod ion-selective electrode was investigated. Electrodes for Cu 2+ based on a thiuram disulphide neutral carrier and for ClO 4 - , SCN - , NO 3 - and Cl - based on a bis(diphenylphosphino)propane-copper complex as ion exchanger exhibited satisfactory performance in a continous-flow system. The response of the anion electrodes in a flow-injection system was near Nernstian in the concentration range 10 −2 -10 −4 or 10 −5 M. Highly reproducible measurements were obtained with sample volumes of 30-100 μl and a sample injection rate of up to 400 h − . The chloride electrode was suitable for the FIA determination of Cl - in sea water and urine.

Hydride formation of evaporated silicon film observed by inelastic electron tunneling spectroscopy

Abstract Inelastic electron tunneling spectroscopy has been used for the characterization of thin films of evaporated silicon on alumina surfaces. The analysis of the tunneling spectra of the silicon films showed the formation of SiH species. The hydride formation is related to the residual water in the vacuum during the evaporation.

Sodium ion sensors based on dibenzo-16-crown-5 compounds with amide side arms

Abstract Lipophilic dibenzo-16-crown-5 compounds with amide-containing side arms attached to the central carbon atom of the three-carbon bridge in the polyether ring have been applied as neutral carriers for sodium ion-selective field-effect transistors (Na+-ISFET′s). ISFET′s based on these lariat ether amides exhibit excellent Na+/K+ selectivities (KNa′K Pot = 7 × 10−3) and Na+/H+ selectivities (KNa′H Pot = 3 × 10−3) with good selectivities for Na+ over other alkali metal cations and alkaline-earth metal cations. High sensor durability was obtained for these ISFET′s.

Characterization of evaporated silicon films by inelastic electron tunneling spectroscopy

Abstract Vibrational spectra of thin (1–2 nm) films of evaporated silicon on alumina surfaces have been measured by inelastic electron tunneling spectroscopy. Analysis of the tunneling spectra of the evaporated Si films and comparison with the vibrational spectra of surface species on crystalline Si formed from reactions with hydrogen atoms, water, and oxygen measured by high-resolution electron energy loss spectroscopy and multiple internal reflection infrared spectroscopy showed the formation of silicon hydride species. Monohydride is predominantly formed in films prepared in high vacuum (10 -6 Torr), whereas dihydride and trihydride are formed in films prepared in an atmosphere of H 2 O (10 -5 Torr). These hydrides are formed from the reaction with residual water molecules in the vacuum system during the evaporation. The tunneling spectra of the Si films evaporated on heated (150–283°C) alumina surfaces showed that the monohydride is stable, while the dihydride and trihydride are unstable at high temperatures. The vibrational frequencies for the hydride species in the films compare more closely to those for crystalline Si surfaces than to those for amorphous Si, suggesting a microcrystalline structure for the evaporated Si films.

Characterization of evaporated germanium films by inelastic electron tunneling spectroscopy

Abstract Vibrational spectra of thin (∼ 1 nm) films of evaporated germanium on alumina surfaces have been measured by inelastic electron tunneling spectroscopy. The tunneling spectra of the evaporated Ge films were compared with the vibrational spectra of surface species on crystalline Ge formed from reactions with atomic hydrogen, water, and oxygen measured by high-resolution electron energy loss spectroscopy and multiple internal reflection infrared spectroscopy and they showed the formation of germanium hydride species. Monohydride is predominantly formed in films prepared both in high vacuum (10 −6 Torr) and in an atmosphere of H 2 O (10 −5 Torr). The tunneling spectra of the heated (125–150°C) Ge films showed that the monohydride is stable in this temperature range. The vibrational frequencies for the hydride species in the films compare more closely to those for crystalline Ge surfaces than to those for amorphous Ge. The hydride is formed from the reaction with residual water molecules in the vacuum system during the evaporation and is considered to be present mainly on the surfaces and grain boundaries of the films to terminate the dangling bonds.