Molar extinction coefficients of some carbohydrates in aqueous solutions

Molar extinction coefficients of some carbohydrates viz. l-arabinose (C₅H₁₀O₅), d-glucose (C₆H₁₂O₆), d-mannose (C₆H₁₂O₆), d-galactose (C₆H₁₂O₆), d(-) fructose (C₆H₁₂O₆) and maltose (C₁₂H₂₄O₁₂) in aqueous solutions have been determined at 81, 356, 511, 662, 1173 and 1332 keV by gamma ray transmission method in a narrow beam good geometry set-up. These coefficients have been found to depend upon the photon energy following a 4-parameter polynomial. These extinction coefficients for different sugars having the same molecular formula have same values varying within experimental uncertainty. Within concentration ranges studied, Beer-Lambert law is obeyed very well.     

Observation of a fluorescent dimer of a sulfonated phthalocyanine

With very few exceptions, phthalocyanine dimers are found to be nonfluorescent. We report here the observation of a fluorescent dimer of a tetrasulfonated copper phthalocyanine in ethanol and water. Fluorescence excitation and emission spectra at room temperature and at 77 K are presented. These are consistent with the conventional model of exciton coupling in a cofacial dimer.     

离子液体作为溶剂/催化剂用于卤代烃对胺的选择性烷基化反应

在三乙胺存在下,在离子液体([bmim]I和[bmim]PF6)中进行了各种卤代烃对胺类化合物中氨基的选择性烷基化反应.反应在相对温和的条件下进行,转化率和选择性优异.离子液体可以回收并重复使用.     

Homoconjugation in the adamantane cage: DFT/IGLO studies of the 1, 3-dehydro-5-adamantyl cation, its isoelectronic boron analogue 1, 3-dehydro-5-boraadamantane, and related systems(1)(,)

The structure of 1,3-dehydro-5-adamantyl cation and its isoelectronic boron analogue 1,3-dehydro-5-boraadamantane as well as some related adamantane systems, hitherto unknown as persistent long-lived species, were investigated by using the density functional theory (DFT) method. (13)C and (11)B NMR chemical shifts of the compounds were also calculated using the IGLO method. Stabilization of the systems due to homoconjugation is discussed.     

Theoretical study of relative width of photonic band gap for the 3-D dielectric structure

Calculations for the relative width (Δω/ω₀) as a function of refractive index and relative radius of the photonic band gap for the fcc closed packed 3-D dielectric microstructure are reported and comparison of experimental observations and theoretical predictions are given. This work is useful for the understanding of photonic crystals and occurrence of the photonic band gap.     

The infra-red spectrum of 13CH3F and the general harmonic force field of methyl fluoride

Analyses of the v ₃, 2v ₃, and (predominantly) v ₁ parallel bands, and of the v ₄ and v ₆ perpendicular fundamentals have been made for ¹³CH₃F in terms of the rotational structure observed with a resolution of ～0·2 cm^-1. In addition, the band centres of the strongly Coriolis-interacting v ₂ and v ₅ fundamentals are accurately located. Some elucidation of the complex Fermi resonance interactions in the 3000 cm^-1 region is achieved through study of spectra of crystalline samples. This enables all three components of the v ₁, 2v ₂, 2v ₅ ⁰ triad to be observed for both ¹²CH₃F and ¹³CH₃F, and estimates to be made for the unperturbed vibration frequencies.

The ¹³C frequency shifts determined for all six fundamentals are used in conjunction with existing frequency, Coriolis ζ, and centrifugal distortion data for CH₃F, CD₃F, CHD₂F and CH₂DF, to determine the general harmonic force field for methyl fluoride. The extra shift data enable all 12 parameters of the force field to be fixed within narrow limits for the first time. The disagreement with predictions of the hybrid orbital model in the A₁ species can be attributed to the effect of trans repulsions arising from the fluorine lone-pair electrons, an effect which contributes to the longer CH bond in methyl fluoride compared with the other methyl halides.     

Vibration-rotation spectra of CD3CN

Rotational structure in two parallel and five perpendicular bands of CD₃CN is fully analyzed at a resolution of 0.2–0.3 cm^?1. The unresolved contour of the ν₈ fundamental is reproduced by contour simulation and a value of ζ8^z determined. Strong A₁-E Coriolis interactions between the close lying fundamentals ν₃ and ν₆, and ν₄ and ν₇ are interpreted by means of computer contour simulations. Marked localized perturbations in the perpendicular ν₅ and ν₅ + ν₆ bands are analyzed and arise through Fermi resonance interactions, most probably with ν₆ + ν₇ + ν₈ and 2ν₃ + ν₆, respectively. A value of A for the ground state is calculated through use of the rotational data for ν₅, ν₆, ν₅ + ν₆, and customary approximations. In conjunction with the microwave B₀ value, it is consistent with a CD₃ group geometry of $\text{r}{}_0\text{= 1.096}\text{A}\text{?}$, α₀(DCD) = 108° 56′.     

High quality beam shaping by square soft-edge diaphragm combined with liquid crystal spatial light modulator

<正>The square soft-edge diaphragm with round angle is designed by Matlab,and is sent to a liquid crystal spatial light modulator by the computer.In order to obtain precompensation for the following laser system, local diaphragm transmission can be adjusted by feedback signals of surface-channel charge-coupled device (SCCD).This method can reduce the diffraction effect and realize no modulation,high stability,high homogeneity,and large scale laser beam.Several parameters of soft-edge diaphragms which affect the laser beam quality are studied systematically,and the optimized values are obtained.The method can avoid the serious modulation of hard edges and provide soft-edge diaphragms of different shapes in a fast and convenient way for the large scale laser beam system.     

Vibration-rotation spectra of CD3CCH

Rotational structure in the perpendicular fundamentals ν₆, ν₇, and ν₈, and in the parallel component of 2ν₉ of CD₃CCH are fully analyzed at a resolution of 0.2–0.3 cm^?1. The A₁-E Coriolis resonances between ν₄ and ν₇, and ν₅ and ν₈ are analyzed by computer contour simulations. These permit accurate location of the parallel fundamentals, and determination of the associated Coriolis interaction constants. The fundamental vibrations ν₅ and ν₈ in CD₃CCH lie only 4 cm^?1 apart, and constitute the closest accidental Coriolis resonance yet studied by the simulation technique. The force field of methyl acetylene, constrained according to the hybrid orbital model, is calculated, using the recently determined molecular structure, and fitting all observed data, many of which have been revised in a number of recent studies.     

Application of the Monte Carlo method to anharmonic force constant calculations: The anharmonic potential functions of some nonlinear symmetrical triatomic molecules

The nonuniqueness of the solution of the quartic anharmonic potential function for some symmetrical nonlinear triatomic molecules is demonstrated using the empirical potential function of Pliva and a Monte Carlo estimation technique. A modification of the method to allow for a varying harmonic force field is introduced. The results obtained indicate that the method might be used as a basis for selection of physically acceptable solutions, with a possible extension to the determination of harmonic potential constants for more complex molecules.