Effects of interaction between the chelate rings and π‐conjugated systems in fused salphen complexes on UV‐Vis‐NIR spectra

Dinuclear (Zn₂, Ni₂, and NiZn) complexes of fused salphen with acene‐type annelation were synthesized from 3,7‐diformyl‐2,6‐dihydroxynaphthalene. The spectroscopic properties of these complexes were compared with those of their constitutional isomers with phene‐type annelation. The acene‐type complexes exhibited a characteristic absorption band in the near‐infrared region that showed a noticeable solvent effect. Time‐dependent density functional theory calculations suggested that the absorption arose from a π → π* transition localized at the naphthalene ring, which was perturbed by the adjoining chelate rings. Effects of the connection topology in the fused salphen complexes are discussed by comparison with those of polycyclic aromatic hydrocarbons.     

Effect of residual oxygen on ionization processes of Si and Si sputtered from Si(1 1 1)-7 × 7 surface

The effect of residual oxygen impurity on ionization processes of Si⁺ and Si²⁺ has been studied quantitatively. In this study, ion sputtering experiments were carried out for a Si(1 1 1)-7 × 7 surface, irradiated with 9-11 keV Ar⁰ and Kr⁰ beam. Even if the oxygen concentration is less than the detection limit of Auger electron spectrometry, SiO⁺ and SiO₂⁺ ions have been appreciably observed. Moreover, as the SiO⁺ and SiO₂⁺ yields increases, the Si⁺ yield is slightly enhanced, whereas the Si²⁺ yield is significantly reduced. From the incidence angle dependence of secondary ion yields, it is confirmed that Si⁺* (Si⁺ with a 2p hole) created in the shallow region from the surface exclusively contributes to Si²⁺ formation. By assuming that the SiO⁺ and SiO₂⁺ yields are proportional to the residual oxygen concentration, these observations are reasonably explained: The increase of Si⁺ with the increase of residual oxygen is caused by a similar effect commonly observed for oxidized surfaces. The decrease of Si²⁺ yield can be explained by the inter-atomic Auger transition between the residual oxygen impurity and Si⁺*, which efficiently interferes the Si²⁺ formation process.     

Quantitative XAFS/EELS analyses of nitrogen species in titanium oxide photocatalysts

With a view to rational designing of a highly functional visible-light TiO₂ photocatalyst, nitrogen atoms were doped into TiO₂ samples by an ion implantation technique which enables to control the depth and concentration of dopants. Although the absorbance in the visible-light region of the sample increased by the nitrogen doping, photocatalytic activity of the sample was not directly connected with the photo-absorbance. The N K-edge X-ray absorption near edge structure (XANES) spectrum of the photocatalytic active sample (A-cat) showed a characteristic double peak at 398 and 401 eV, and the XANES spectrum of the inactive sample (I-cat) a distinct single peak around 401 eV. These features of the XANES spectra were well reproduced by theoretical simulations based on the model where an O atom in TiO₂ was replaced by N ((N)s) for A-cat, and that of quasi NO₂ molecule ((NO₂)s) for I-cat. Therefore, we have concluded that the nitrogen atom occupying the oxygen site of TiO₂ is photocatalytic active species effective for visible light photocatalysis. In addition, the quantitative XANES/ELNES analysis has revealed that the photo-absorbance ratio of I-cat to A-cat corresponds well to the ratio of total doped nitrogen concentration rather than photocatalytic active nitrogen ((N)s) concentration. This result indicates that not only (N)s but also (NO₂)s also absorb the visible light. Thus, the absorbance in the visible-light region is not necessarily an indication of the visible-light response of a photocatalyst.     

Chemical braking exhibited by ethynylhelicene (M)-nonamer in solution: Competitive reaction system of self-catalysis to form double-helix and approach towards equilibrium to form random-coil

Chemical braking occurs in a dilute solution during a structural change of ethynylhelicene (M)-nonamer from the metastable double-helix state to the random-coil state, being at equilibrium, where the reaction is initially rapid and then substantially retard. The chemical braking is derived from the competitive chemical reaction system in dilute solution: An energetically uphill self-catalytic reaction to form double-helix and the downhill reaction to form the random-coil.     

Influence of shearing process on domain structure and magnetic properties of non-oriented electrical steel

The influence of shearing on the magnetic properties and domain structure of 0.5 mm thick non-oriented electrical steel was studied. In the region from 1 to 1.4 mm from the sheared edge, a striped domain pattern that indicated the existence of elastic strain was observed. From the degradation tendency of flux density with respect to shearing width, the width of the degraded region near the edge increased as the magnetic field decreased. These results suggested that the change in the flux density at high magnetic fields over 300 A/m were mainly dependent on the characteristics of the edge vicinity where the domain pattern was influenced by shearing.     

36-W diode-pumped continuous-wave 1319-nm Nd:YAG ceramic laser

Continuous-wave output at 1319 nm was obtained from a laser-diode-pumped 1% ceramic Nd:YAG laser. As much as 36.3-W output was obtained under pump power of 290 W, with an optical-to-optical conversion efficiency of 12.5%.     

Nuclear laser spectroscopy using a laser-microwave double-resonance method with an ion trap

With an RF-trap connected to an Isotope Separator On-Line (ISOL), we aim to study nuclear magnetic properties of nuclei far from stability through the hyperfine interaction by a laser-microwave double-resonance method. As a first step, the hyperfine splitting of the ground state of⁸⁷Sr⁺ was measured, and the magnetic dipole hyperfine constant was precisely determined to beA=−1,000,470.8(2.4) kHz.     

Characterization of iron oxides and hydroxides in the sand of Flaming Mountain

A sand sample collected at the foot of Flaming Mountain was studied further. On the basis of the change in the relative intensity after heat treatment, one of the sextets observed in its Mössbauer spectrum at liquid nitrogen temperature was ascribed to goethite. This result provides a useful information on the geological history of the region where the mountain is located.     

Partition of transition elements betwen soil and caatinger wood grown in North-east Brazil determined by neutron activation analysis

Seven representative wood species constituting caatinger forest were chosen to analyze Sc, V, Cr, Mn, Fe and Co, as well as Na, Mg and Al, by instrumental neutron activation analysis. In most cases of the soil, the concentration of the element tended to be higher with the increase of depth. Generally, the element partition from soil to root was higher in Mg and Co, whereas V showed higher partition rate from root to bark. The correlation within the elements was higher in the order of soil, root and bark.