Raman scattering in low wavenumber region as a new probe to structural properties of microcrystalline silicon

The structural properties of microcrystalline silicon (μc-Si) are studied by Raman scattering. It is found that the intensity of each Raman band closely correlates with the absorption coefficient in the interband region and that the Raman band at ca. 150 cm^?1 is a sensitive probe to randomness of Si-Si bonding structure in μc-Si.     

Selective cleavage of polycyclic cyclopropanes by electrochemical oxidation

Anodic oxidation in acetic acid of polycyclic cyclopropanes, namely tricyclene, cyclofenchene, and longicyclene, followed by hydrolysis brought about stereo- and regioselective formation of the corresponding homoallylic alcohols as the main product in good yields.     

Synthesis and complexation of a novel cyclophane

A novel cyclophane, 17, 17, 40, 40-tetramethyl-7, 30-dinitro-1, 10, 24, 33-tetraoxa[2.2.1.2.2.1] metaparaparametaparaparacyclophane, was synthesized by 2:2 cyclization of 3,5-bis(bromomethyl)nitrobenzene, derived from 3,5-dimethylnitrobenzene, and bisphenol A. The cyclophane was found to form 1:1 complex with benzene.     

Concentration wave description of an early stage kinetics of clustering and ordering in ordered phase

Kinetic theory of early stages of coherent clustering and continuous ordering in ordered phase is developed using the concept of concentration waves on the assumption of mean field energy. Linear differential equations of atom diffusion in ordered phase are solved by diagonalizing the coefficient matrix of the equations. It is shown that at the early stages of the reaction the concentration (fluctuation) waves evolve exponentially with respect to time on the sublattices of the ordered phase.The theory is applied to the Fe-10.9 at. %Si alloy which exhibits a sequence of transitions on aging at 775K. It is proved that the first transition from the disordered to the B2 phase occurs purely due to the kinetic reason that the amplification factors of the fluctuation waves have a positive maximum value only at the superlattice point of the B2 structure in the first Brillouin zone of the disordered phase. The second transition, which is from the metastable B2 phase to the stable phase, i.e. the spinodally decomposed D03 phase, is also explained consistently by the present theory that the amplifications calculated in the B2 phase exhibit two positive maxima in the first Brillouin zone. The maximum at point $\text{(q) = (}\text{1}\text{2}\text{1}\text{2}\text{1}\text{2}\text{)}$ represents the amplification factor of the D03 ordering-wave in the B2 phase, while the other close to the Brillouin zone center represents the amplification factor of the fluctuation wave of the spinodal decomposition.     

Determination of inorganic arsenic and organic arsenic compounds in marine organisms by hydride generation/cold trap/gas chromatography— mass spectrometry

The behavior of arsenite, methylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, dimethyl-R-arsine oxides, and trimethyl-R-arsonium compounds (R = carboxymethyl, 2-carboxyethyl, 2-hydroxyethyl) toward sodium borohydride and hot aqueous sodium hydroxide was investigated. The arsines obtained by sodium borohydride reduction of the undigested and digested solutions were collected in a liquid-nitrogen cooled trap, separated with a gas chromatograph, and detected with a mass spectrometer in the selected-ion-monitoring mode. The investigated arsenic compounds were stable in hot 2 mol dm^?3 sodium hydroxide except arsenobetaine [trimethyl(carboxymethyl)arsonium zwitterion] that was converted to trimethylarsine oxide, and dimethyl(ribosyl)arsine oxides that were decomposed to dimethylarsinic acid. Hydride generation before and after digestion of extracts from marine organisms allowed inorganic arsenic, methylated arsenic, arsenobetaine, and ribosyl arsenic compounds to be identified and quantified. This method was applied to extracts from shellfish, fish, crustaceans, and seaweeds.     

Further evidence for the intramolecular charge-transfer interaction between tropylium ion and remote benzene rings in 9,10-dihydro-9,10-(1,2-tropylio)anthracene tetrafluoroborate and its methyl derivatives

A series of 9,10-dihydro-9,10-(1,2-tropylio)anthracene tetrafluoroborates

has been prepared. The intramolecular charge-transfer interactions in

were confirmed by their UV spectra and pK_R+ values. As a model compound 1,2,3,4-tetrahydro-1,4-(1,2-tropylio)naphthalene tetrafluoroborate ($\text{5}$)_was also examined.     

Optimized perturbation theory in quantum electrodynamics

The optimized perturbation expansions, Grunberg's fastest apparent convergence and Stevenson's principle of minimal sensitivity, are applied to some low-energy QED quantities. The optimization does not disturb the experimentally established values, and, at higher orders, its effects are in the direction of reducing small differences between theoretical and experimental values.