Determination of trace element in a silicon single crystal

Neutron activation analysis was applied to the determination of trace impurity elements in a silicon ingot. Detection limits of 36 elements were calculated semi — empirically and compared with minimum concentrations detected in a silicon single crystal. The sources of the impurities were estimated from element concentrations detected in polycrystalline silicon and a quartz crucible. Segregation coefficients were determined from the concentration curves in a single crystal and discussed by comparing with reported values.     

Influence of electroless nickel plating of hydrogen-absorbing alloys on cycle characteristics of nickel-metal hydride batteries

The effects of electroless nickel plating of a hydrogen-absorbing alloy on the cycle characteristics of a nickel-metal hydride battery were investigated. The cycle life was improved by employing an electroless nickel-plated hydrogen-absorbing alloy for the negative electrode, which retained the same high-rate level and low-temperature characteristics compared to a cell using a non-plated hydrogen-absorbing alloy. The electroless nickel-plated hydrogen-absorbing alloy provided better electrochemical characteristics when its surface was partly and tightly covered by nickel particles under optimal electroless plating conditions.     

Photocrosslinking of poly(methyl acrylate)s containing the 1,3-dioxolane structure as a pendant group

(2-Ethyl-2-methyl-1,3-dioxolan-4-yl)methyl- and (2-methyl-2-phenyl-1,3-dioxolan-4-yl) methyl acrylates were synthesized and polymerized. The photochemical behavior of the resulting polymers was investigated to determine whether the polymers pending on the 1,3-dioxolane structure were readily crosslinked with ultraviolet (UV) irradiation. The degree of crosslinking was estimated by the weight-loss method by immersion in acetone, with the result that the polymer with an aromatic substituent was more photocrosslinkable than the polymer that bore the aliphatic substituent. The catalytic effect on photocrosslinking of polymers was also studied by using benzoin and cobalt naphthenate. The infrared (IR) spectra of polymers irradiated in air that showed the new band at 3450 cm^?1 were attributed to a hydroxyl group; however, the spectra of polymers irradiated in vacuum displayed little absorption at 3450 cm^?1. To explain the mechanism of crosslinking model compounds were prepared and irradiated with UV light. It was concluded that crosslinking proceeds mainly from the fission of the 1,3-dioxolane ring and the coupling of the yielding radicals, together with autooxidation by atmospheric oxygen.     

Color modulation for chemiluminescence of a dioxetane bearing a 3-(anthracen-9-yl)-5-hydroxyphenyl moiety induced by a complex of crown ether with potassium tert-butoxide

Color modulation was first observed for CT-induced chemiluminescent decomposition of a dioxetane bearing a 3-(anthracen-9-yl)-5-hydroxyphenyl induced by a complex of crown ether with potassium tert-butoxide in benzene system. The phenomenon is rationalized by conformational change of a biaryl moiety in the emitter, which is induced by steric interaction of anthryl and a plane of crown ether complex.     

Thick single crystalline vanadyl phthalocyanine film epitaxially grown on KBr crystal by molecular beam epitaxy

Structural analyses are reported of 5 μm thick VOPc films grown on a KBr(001) surface by the MBE technique. The crystal is monoclinic with lattice parameters a = 14.2 Å, b = 13.1 Å, c = 12.7 Å and β = 103.2°. The orientation of the unit cell is influenced by the crystal lattice of the substrate even in this thickness range: The projections of the a- and b-axes of VOPc onto the (001) plane of KBr coincide with the [110] directions of KBr. Four kinds of crystal orientations were observed in pole figure measurements.     

Precise measurement of the magnetic moment of doubly closed shell − 1 nucleon nucleus15O(I π1/2−,T 1/2=122 s)

The magnetic moment of¹⁵O(I=1/2^–,T _1/2=122 s) has been measured precisely by use of the -NMR detection of¹⁵O in TiO₂ as, |(¹⁵O; 1/2^–)|=0.71951 (12) µ_N. The effective nucleon mass in the nuclei around mass number 16 was discussed using the isoscalar moment deduced in connection with the magnetic moment of¹⁵N.     

NMR line width of12B in Pt detected by β-NMR

NMR spectra of¹²B in Pt (fcc) metal were observed by use of the -NMR detection method. A sharp single line was observed by use of an annealed Pt foil for the implantation medium. The dipolar broadening has been determined to be 332±30 Hz (HWHM).