Study on the interface structure: Diamond thin film epitaxy on (001) silicon substrate

An interesting interface structure between diamond film and silicon substrate has been observed. That is, according to the deformation of the diamond film crystal sturcture, a strictly 3:2 matching of the two lattices across the interface is obtained. This result clearly indicates that misfit dislocations at the interface and "epitaxial tilting" are not the only two ways to overcome the 1.5% residual misfit.

X-ray photoelectron spectroscopy and mass spectra study of alpha-amino acid

X-ray photoelectron spectroscopy and mass spectrometry have been used to study the ten alpha-Amino Acids. The chemical shiftss of N-1s electron binding energy have been explained by means of the difference in the hydrocarbon group of amino acids. The influence of the hydrocarbon group on NH2 has been disscussed using the XPS and MS results.

Mass spectrometry study combined with theoretical calculation on the unimolecular fragmentation of tetrahydroimidazole-substituted methylene beta-diketones

Studies of low-energy collision-induced dissociation and isotopic labeling on ionized tetrahydroimidazole-substituted methylene P-diketones by tandem mass spectrometry showed that their unimolecular fragmentations may involve the reactions of intermediate ion/neutral complexes and multistep rearrangements. The corresponding mechanisms were proved by semiemipirical calculations of PM3 and AM1 methods.

Study on the bond covalency and bond susceptibility in NdCr1-xMxO3 (M=Mn, Fe, Co)

Bond covalency, bond susceptibility and macroscopic linear susceptibility in NdCr1-xMxO3 (M=Mn, Fe, Co, 0.0 less than or equal to x less than or equal to 1.0) are investigated by complex chemical bond theory. The results indicate the bond covalencies are insensitive to the doping level. With the increasing doping level, the macroscopic linear susceptibilities increase for M=Mn, Fe, decrease for M=Co. The valence state of Cr can be strongly influenced by the properties of the doping ions.

Study on the regulation of diorganogermanium compounds on the Maillard reaction of histidine and glycine by fluorescence spectrum

The suppression of diorganogermanium compounds on the Maillard reaction of histidine (His) and glycine (Gly) with glucose has been determined by fluorescence spectrum under physiological conditions. The title compounds show inhibition for the fluorescence intensity (FI) of glycosylated amino acids stronger than Ge-132.

Fabrication and fluorescence study of sensitizing dye TiO2 films

Fluorescence spectra of the sensitizing dye/TiO2 bilayer films were studied. Charge-transfer complexes were formed in the above bilayer.

Study of (TPP)H-2 vapor deposited film on iron

The film by tetraphenylporphyrin((TPP)H-2) vapor deposition on iron was investigated by means of XPS, SEM and visible spectroscopy. N(1s) binding energy characteristic of(TPP)H-2 was gained directly from the deposited samples. N(1s) binding energy of the surface was greatly changed after the deposited sample was washed with solvent. It is indicated that the deposited film is composed of an outer-layer of physically adsorbed (TPP)H-2, and an inner-layer of chemically modified (TPP)H-2.

In-situ FTIR spectroelectrochemical study of chromium hexacyanoferrate on glassy carbon electrode

Chromium hexacyanoferrate (CrHCF) modified grassy carbon electrode (GC) in different electrolytes was studied by cyclic voltammetry and in situ FTIR spectroelectrochemistry. The results indicate that the behavior of CrHCF firm can be understood in term of two structures: Cr1/3Cr(III)Fe(II)(CN), and MCr(III)Fe(II)(CN)(6). Besides,the film exists in amorphous state: the outer layer is porous film, while the inner layer is relatively compact. According to the electrochemical reaction of CrHCF, the lattice can contract and expand with the cations' diffusion.

Chemical environment code and measure of molecular similarity

A new scheme for the code of chemical environments of compounds is described in this paper, and three molecular similarity methods have been used to select nearest neighbors from four different types of probe compounds. One of the methods is based on the C-13 NMR spectra. The second method is based on the code of chemical environments and molecular topological index A(x). The third approach, i.e. the Tanimoto coefficient, is also based on the code of chemical environments, but not to use the topological index. Five nearest neighbors for each probe compound using these three molecular similarity methods were determined and taken from the database of 7309 structures. The results indicate that the scheme of the chemical environment code and the method for similarity measure of intermolecules suggested in this study are reasonable. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.

Preliminary study on the charge transfer and bond ionicity of binary crystals

Charge transfer and bond ionicity of some monovalent, divalent, and trivalent binary crystals of A(N)B(8-N) type have been investigated using the self-consistent method. The method divides the binary crystal systems into two subsystems which contain only one kind of element each in physical space. The charge transfer values are obtained by adjusting the charge in a self-consistent way. Based on the obtained charge transfer values, an empirical formula for bond ionicity has been proposed. It has been shown that the present results for bond ionicity are in good agreement with the previous theoretical study delivered by Levine and Pauling. The results also indicate that a large magnitude of charge transfer (or less excess charge in the bonding region) gives rise to high bond ionicity (or low bond covalency); this agrees well with the viewpoint that the excess charge in the bonding region is the origin of the formation of bond covalency. (C) 1998 American Institute of Physics. [S0021-9606(98)00837-X].

In-situ microscopic FTIR spectroelectrochemical study of the reduction of K3Fe(CN)(6) in polymer electrolyte

Cyclic voltammetry and in-situ microscopic FTIR spectroelectrochemistry were used for the electrochemical and vibrational characterizations of the reduction process of K3Fe (CN)(6) in polyethylene glycol(PEG) with LiClO4 as supporting electrolyte at a Pt microelectrode. The rate of electron transfer is a function of the concentration of the supporting electrolyte. The redox potentials and cyclic voltammetric currents vary with Li/O molar ratio. The bl-situ spectroelectrochemistry shows that the infrared spectra are influenced by the concentration of LiClO4. The bridging cyanide groups with a structure Fe-I-C drop N ... Fe-I-C drop N are formed during the reduction process of K3Fe (CN)(6). There may be an activated complex between the Lif cation and the complex anion.

In situ microscopic FTIR spectroelectrochemistry study of oxidation of L-ascorbic acid in polymer electrolyte (PEG/LiClO4)

In situ microscopic FTIR spectroelectrochemistry behavior of L-ascorbic acid (H(2)A) in polymer electrolyte is reported for the first time. H(2)A undergoes a two-step oxidation, The oxidation waves shift towards more anodic potential values when the scan rate increases. The peak currents of the oxidation waves are proportional to the square roots of scan rate up to 100 mV/s, The in situ infrared spectra suggest that the product of the oxidation be dehydroascorbic acid, which may exist as a dimer.

The kinetics study in liquid-liquid systems with constant interfacial area cell with Laminar flow

A novel constant interfacial cell with laminar flow is proposed as an approach to obtain extraction kinetics data in liquid-liquid systems. Applications and theoretical fundamentals of the apparatus have been elaborated.. The equation which can express the mass transfer of liquid-liquid system run in the constant interfacial cell with laminar flow is deduced. Simulations from the equations indicate that diffusivity is a suitable factor to represent the characteristics of extraction kinetics rather than the extraction rate in the diffusion controlling step. The dependence of the aqueous phase concentration on time is recommended to determine the extraction regime. The diffusivities of the EuCl3-HDEHP extraction system obtained by different methods are compared to certify the hydrodynamic theory of the cell. The diffusivities of the ErCl3-HEH/EHP extraction system are determined, which show that this technique is a convenient method to obtain the diffusivities in the liquid-liquid system and to determine the extraction regime. (C) 1998 Elsevier Science Ltd. All rights reserved.

Matrixassisted laser desorption/ionization mass spectral study of saccharides

Matrixassisted laser desorption/ionization (MALDI) mass spectra of saccharides with three common matrixes were studied here. It is shown that Na+ and K+ play important roles in the determination of oligasaccharide molecule weight and the molecular weights (MW) of glucans(dextran) with MW more than 10 000 is determined successfully with the help of column chromatography, By comparing the effects of three matrixes in saccharide analysis and comparing positive-ion and negative-ion matrixassisted laser desorption/ionization mass spectra of oligo- and polysaccharides, the most suitable matrix for saccharide analysis, 2,5-dihydroxylbezonic acid (DHB), is selected and the ion formation processes of saccharides under matrix-assisted laser adsorption/ionization condition are clarified.

Semiempirical study on the valences of Cu and bond covalency in Y1-xCaxBa2Cu3O6+y

The valences of Cu and bond covalencies in Y1-xCaxBa2Cu3O6+y, have been investigated using complex chemical bond theory, This theory is the generalization of Phillips, Van Vechten, Levine, and Tanaka's scheme. The results indicate that the valences of Cu(1) and Cu(2) in our calculation agree well with those obtained by the bond valence sum method. The valences of Cu(1) and Cu(2) in our calculation also suggest that the holes introduced by Ca substitution only reside in CuO2 planes and there is a competing mechanism for the hole density in CuO2 planes between,Ca doping and oxygen depletion. These conclusions are in satisfactory agreement with experiments. The calculated ordering of covalencies is Cu(1)-O(4)>Cu(1)-O(1)>Cu(2)-O(2,3)>Cu(2)-O(1)>Ca-O>Y-O similar to Ba-O, regardless of the Ca doping level and oxygen content. [S0163-1829(98)03325-6].