Intensity‐Carrying Modes in Raman and Raman Optical Activity Spectroscopy

We describe a quantum‐chemical approach for the determination of modes with maximum Raman and Raman optical activity (ROA) intensity by maximizing the intensities with respect to the Raman and Raman optical activity intensity, respectively, which is shown to lead to eigenvalue equations. The intensity‐carrying modes are in general hypothetical modes and do not directly correspond to a certain normal mode in the spectrum. However, they provide information about those molecular distortions leading to intense bands in the spectrum. Modes with maximum Raman intensity are presented for propane‐1,3‐dione, propane‐1,3‐dionate, and Λ‐tris(propane‐1,3‐dionato)cobalt(III). Moreover, the mode with highest ROA intensity is examined for this chiral cobalt complex and also for the (chiral) amino acid L ‐tryptophan. The Raman and ROA high‐intensity modes are an optimal starting guess for intensity‐tracking calculations, in which selectively normal modes with high Raman or ROA intensity are converged. We present the first Raman and ROA intensity‐tracking calculations. These reveal a high potential for large molecules, for which the selective calculation of normal modes with high intensity is desirable in view of the large computational effort required for the calculation of Raman and ROA polarizability property tensors.     

Scattering of circularly polarized light from the isotropic to the cholesteric phase of cholesteryl oleyl carbonate

The Rayleigh intensity and linewidth of circularly polarized incident light have been measured in the isotropic phases and blue phases of cholesteryl oleyl carbonate. In the isotropic phase the intensity data show mean field behaviour. In the blue phase region the scattering of right handed or left handed circularly polarized light shows a different q dependence for the intensity as well as for the linewidth. The correlation function of the intensity fluctuations can be fitted to two exponentials. The experimental results are compared with the predictions of the theory proposed by Hornreich and Shtrikman.     

紫外线辐照光强对HDPE化学结构及对HDPE/PC共混体系增容效应的影响

采用FT-IR,XPS,凝胶分析以及熔融指数、接触角和力学性能测定,研究了不 同紫外辐照光强对高密度聚乙烯（HDPE）的化学结构、流动性、亲水性和辐照改性 HDPE在HDPE/聚碳酸酯（PC）共混体系中的增容效应的影响。在相同辐照时间下, 随紫外光强提高,引入HDPE分子链的含氧基团数量增加;在辐照过程中,紫外光强 对HDPE的交联有显著影响,在较低光强（32W/m~2）下辐照24h的HDPE无凝胶生成, 便在较高光强（45和78W/m~2）下辐照24h后,HDPE产生凝胶,其含量随紫外光强提 高而增多;与未辐照HDPE相比,较高光强下辐照HDPE的熔融指数有所下降,但其亲 水性得到明显改善;紫外辐照改性HDPE对HDPE/PC体系有增容作用,随紫外光强提 高其增容效应明显增强。与未增容HDPE/PC（80/20）体系相比,加入20%辐照 24hHDPE（光强78W/m~2）的HDPE/PC共混物的拉伸屈服强度从26.3MPa提高到30. 2MPa,缺口冲击强度从51J/m提高到158J/m。     

Investigation of chemically modified barium titanate beads as surface-enhanced Raman scattering (SERS) active substrates for the detection of benzene thiol, 1,2-benzene dithiol, and rhodamine 6G

SERS active surfaces were prepared by depositing silver films using Tollen's reaction on to barium titanate beads. The SERS activity of the resulting surfaces was probed using two thiols (benzene thiol and 1,2-benzene dithiol) and rhodamine 6G. The intensity of the SERS signal for the three analytes was investigated as a function of silver deposition time. The results indicate that the SERS intensity increased with increasing thickness of the silver film until a maximum signal intensity was achieved; additional silver deposition resulted in a decrease in the SERS intensity for all of the studied molecules. SEM measurement of the Ag coated barium titanate beads, as a function of silver deposition time, indicate that maximum SERS intensity corresponded with the formation of atomic scale islands of silver nanoparticles. Complete silver coverage of the beads resulted in a decreased SERS signal and the most intense SERS signals were observed at deposition times of 30 min for the thiols and 20 min for rhodamine 6G.     

Scattering of circularly polarized light from the isotropic to the cholesteric phase of cholesteryl oleyl carbonate

The Rayleigh intensity and linewidth of circularly polarized incident light have been measured in the isotropic phases and blue phases of cholesteryl oleyl carbonate. In the isotropic phase the intensity data show mean field behaviour. In the blue phase region the scattering of right handed or left handed circularly polarized light shows a different q dependence for the intensity as well as for the linewidth. The correlation function of the intensity fluctuations can be fitted to two exponentials. The experimental results are compared with the predictions of the theory proposed by Hornreich and Shtrikman.     

A new method for bidimensional analysis of interferometric patterns of liquid films

A new method for bidimensional analysis of interferometric patterns of wetting liquid films obtained with the captive bubble technique is described. This method replaces one-dimensional analysis along various intensity profiles with analysis of one average intensity profile. The advantage is to concentrate the surface characteristics of the whole film image into a single intensity profile.     

Fuel concentration measurement of premixed mixture using spark-induced breakdown spectroscopy

This study determined the local equivalence ratio of a CH₄/air mixture in a laminar premixed flame using spark-induced breakdown spectroscopy (SIBS) with a fiber-coupled intensified charge coupled device (ICCD) spectrometer. Spectrally resolved emission spectra of plasma generated by a spark plug were investigated for their potential to measure local fuel concentrations in a premixed mixture. The influence of key parameters, such as the camera gate timing and spark energy, on the intensity of radical emission was illustrated. The intensity ratio of CN/NH had a greater sensitivity to the equivalence ratio than did that of CN/OH, and the local equivalence ratio could be obtained with high resolution by measuring the local intensity ratios of CN/NH. Moreover, a spark-plug sensor with an optical fiber was developed for application in spark-ignition engines. The atomic emission intensity during the breakdown and arc phases of spark discharge could be obtained using the fiber-optic spark-plug sensor. The H_α/O intensity showed better linearity than the CN/NH intensity ratio in lean mixtures. The results presented here confirm the use of SIBS as a diagnostic tool for spark-ignition engines.     

反胶束体系中有机染料PDS对TiO_2纳米粒子的表面修饰

反胶束法制备纳米粒子是 2 0世纪 80年代兴起的研究领域[1] .反胶束是指表面活性剂在非极性溶剂中定向排列而自发形成的聚集体 [2 ] ,反胶束的“水池”是一种特殊的纳米空间 ,以此作为微反应器 ,通过控制含水量 W0 ( W0 =[H2 O]/[Surft.],即水与表面活性剂的摩尔比 )和选择不同的表面活性剂种类及浓度可以获得单分散的粒径小于 1 0 nm的微粒 [3～ 5] .Ti O2 作为一种典型的光催化剂 ,由于其化学性质稳定、氧化还原性强 ,且具有抗光阴极腐蚀性、难溶、无毒、成本低等特点 ,在有机污染物的去除 ,废水处理等方面具有广阔的应用前景[6 ] .而…     

Optical Diagnostics of the Effect of Oxygen on Bi-Level Contact Etch

The effect of oxygen flow rate on bi-level contact etch was studied by observing uv-visible emission from the plasma, during CHF₃/CO/O₂ etching of di-electric layers consisting of SiO₂ and SiN_x. The emission intensity of CN at 387 nm drifted progressively from wafer to wafer during plasma etch. Such a phenomenon became more obvious when using low or high oxygen flow rate, whereas for intermediate flow rates, no significant drift of emission intensity was observed. The critical dimension (CD) bias of each wafer showed a strong correlation with CN emission intensity. Possible mechanisms for such an intensity drift phenomenon are proposed. The drift of emission intensity indicates that the contribution of chamber wall polymers in wafer etching is non-negligible. The CN emission intensity is an indication of the magnitude of etching rate. Our results suggest that the variation of plasma emission intensity might be used as an index for in-line monitoring of CD bias fluctuation.     

Correlation in spatial intensity distribution between volumetric bubble oscillations and sonochemiluminescence in a multibubble system

The correlation in spatial intensity distribution between volumetric oscillation of multibubble and sonochemiluminescence in an ultrasonic standing-wave field is investigated through the measurements of scattered light from bubbles by changing the measuring position in the direction of sound propagation and sonochemiluminescence with luminol. When a thin light sheet, finer than half the wavelength of sound, is introduced into the cavitation bubbles at the anti-node of the sound pressure, the scattered light intensity oscillates temporally. The peak-to-peak light intensity corresponds to the number of the bubbles which contribute to the sonochemical reaction because the radius for oscillating bubbles at pressure antinode is restrictive in a certain range due to the shape instability and the action of Bjerknes force that expels from anti-node bubbles larger than the resonant size. The experimental results show that at the side near the water surface, the peak-to-peak light intensity is larger in comparison with the intensity near the sound source, and this tendency becomes apparent at higher input power. These light scattering results correspond with the spatial intensity distribution of the sonochemiluminescence with luminol. Therefore, it is interpreted that most of the cavitation bubbles contributing to the sonochemical reactions in the standing wave field exist near liquid surface. Present method of light scattering in reference with the image of the sonochemiluminescence is promising for evaluating spatial distribution of violently oscillating cavitation bubbles effective for sonochemical reactions.     

Effects of pressure and solvents on the infrared absorption intensity of the O-H stretching mode of phenol in solutions

Effects of pressure and solvents on the infrared spectrum of phenol in solutions have been investigated using a hydrostatic high-pressure cell with synthetic diamond windows. For the first time, we performed a quantitative investigation of the effect of pressure on the absolute intensity of O-H stretching mode up to 150 MPa (in CCl4) and 200 MPa (in CS2). For comparison, we measured the effect of solvents on the absorption intensity. The Polo-Wilson theory, which is the most traditional theory for medium effects on the intensity, was tested for present results. The pressure dependence was in sufficient agreement with their formula, while the solvent dependence is unsatisfactory. This suggests that the traditional intensity correction by Polo-Wilson's formula is practically valid for pressure-tuning infrared experiments.     

Photovoltaic properties of Au/beta-carotene/n-Si organic solar cells

Photovoltaic properties of Au/beta-carotene/n-Si organic solar cells characterized by current-voltage and capacitance-voltage measurements have been investigated. The photocurrent in the reverse direction increases with increasing illumination intensity. The I(sc) increases linearly with light intensity. The I(sc) dependence of light intensity follows a power law I(sc) approximately F(alpha). The exponent alpha was found to be 1.38. This indicates a monomolecular recombination in this device. Au/beta-carotene/n-Si organic solar cells give an open-circuit voltage of 0.316 V and a short-circuit current of 2.33 x 10(-4) A at light intensity of 6 W/m(2). The best conversion efficiency for Au/beta-carotene/n-Si solar cells was found to be 23.3% at a light intensity of 6 W/m(2).     

Passive micromixer for luminol-peroxide chemiluminescence detection

This paper reports a microchip with an integrated passive micromixer based on chaotic advection. The micromixer with staggered herringbone structures was used for luminol-peroxide chemiluminescence detection. The micromixer was examined to assess its suitability for chemiluminescence reaction. The relationship between the flow rate and the location of maximum chemiluminescence intensity was investigated. The light intensity was detected using an optical fiber attached along the mixing channel and a photon detector. A linear correlation between chemiluminescence intensity and the concentration of cobalt(ii) ions or hydrogen peroxide was observed. This microchip has a potential application in environmental monitoring for industries involved in heavy metals and in medical diagnostics.     

Simultaneous Analysis of Phosphorylated Peptides by MALDI-TOF-MS

Six peptides with various phosphorylation sensitivities for protein kinase A (PKA) were used for the simultaneous analysis of phosphorylated peptides using matrix-assisted laser desorption/ionization-time-of-flight (MALDI-TOF) mass spectrometry. The mixture of six peptides was reacted with PKA and was analyzed by MALDI-TOF mass spectrometry. The intensity of all peaks except one phosphorylated peptide peak was very low (<20%). Moreover, we examined whether the addition of diammonium citrate to CHCA matrix at concentrations of 1–20 mg mL^?1 can increase the peak intensity of peptides and phosphorylated peptides. The addition of diammonium citrate increased the peak intensity of peptides and phosphorylated peptides, but an increase in the intensity was unsatisfactory. Our study strongly suggests that MALDI-TOF mass spectrometry is not suitable for the simultaneous analysis of phosphorylated peptides.     

Raman spectra of pyridine adsorbed on a copper electrode

The surface enhanced Raman scattering (SERS) of pyridine adsorbed on a copper electrode was observed with 647.1 nm excitation and the dependence of the Raman intensity as a function of electrode potential was obtained for the most intense bands. The results are compared with reported intensity and frequency values for the silver/pyridine system.     

Scattering of light by disordered spherulites. II. Effect of disorder in the magnitude of the anisotropy

The contribution to the disorder scattering by imperfect spherulites resulting from fluctuations in the magnitude of the anisotropy is analyzed for two-dimensional spherulites. The fluctuations are described in terms of a parameter characterizing the meansquare amplitude of the fluctuation and a correlation function describing the distance over which the correlation occurs. Cases considered are those where the correlation depends on either the radial or the angular separation of the scattering volume elements. As with the case of disorder in orientation, one finds that disorder in anisotropy may result in a nonzero value of intensity at μ = 0° and 90°, a decrease in the higher-order variation of scattered intensity with θ, and an increase in the intensity of scattering at higher values of θ over that for a perfect spherulite. In addition, disorder in the angular direction leads to an increase in the scattered intensity at small values of θ as compared with the zero intensity of scattering from a perfect spherulite at θ = 0°.     

Luminescence of ytterbium(III) in mixed-ligand compounds with cinnamic acid and neutral phosphorus-containing ligands

The luminescence spectral characteristics of mixed-ligand compounds of ytterbium(III) with cinnamic acid and neutral phosphorus-containing ligands were studied by luminescence spectroscopy. The intensity of luminescence of the compounds was determined. The highest intensity of luminescence was found for the ytterbium(III) compound with triphenylphosphine oxide.     

Selectivity enhancements for the determination of thorium by flow-injection analysis through the formation of the Th-DTPA-HQS fluorescent ternary complex

Addition of diethylenetriaminepentaacetic acid (DTPA) to the fluorescent binary complex of thorium and 8-hydroxyquinoline-5-sulfonic acid (HQS) forms the Th-DTPA-HQS fluorescent ternary complex. The formation of this ternary complex enhances the selectivity for the determination of thorium. Excesses of DTPA and HQS are used as reagents in flow-injection analysis to detect thorium. The excess DTPA effectively masks potentially interfering ions by preventing the formation of fluorescent binary metal-HQS complexes. The presence of lanthanides and transition metals does not interfere with the thorium detection with this method (the ratio of molar intensity for metals to molar intensity for thorium is <0.3% with the exception of lutetium, for which molar intensity ratio is 1.34%). The detection limit for thorium is 12 ng ml(-1).     

Effects of pressure and solvents on the infrared absorption intensities of C-I stretching modes of methyl and ethyl iodides in solutions

We have investigated effects of pressure and solvents on infrared intensities of methyl and ethyl iodides in solutions using a hydrostatic high-pressure cell with synthetic diamond windows. We focused on the absolute intensity of the C-I stretching mode, which was measured in carbon disulfide solvent up to 300MPa and at 293K, and in n-hexane solvent at 298K. For comparison, we investigated the effect of solvents on the absorption intensity. Effects of pressure and solvents on the infrared intensity were analyzed using two electrostatic models, which assume the shape of solute cavity as sphere or spheroid. The latter model is approximately in agreement with both effects on the intensity, particularly, for the pressure effect. This paper demonstrated that the electrostatic model taking the shape of the cavity into account is useful to explain the medium effect on the infrared intensity and also suggests that more improved models could provide information of the solvation structure from the medium effect on the infrared intensity.     

Enhanced Fluorescence Turn‐on Imaging of Hypochlorous Acid in Living Immune and Cancer Cells

Two closely related phenyl selenyl based boron‐dipyrromethene (BODIPY) turn‐on fluorescent probes for the detection of hypochlorous acid (HOCl) were synthesized for studies in chemical biology; emission intensity is modulated by a photoinduced electron‐transfer (PET) process. Probe 2 intrinsically shows a negligible background signal; however, after reaction with HOCl, chemical oxidation of selenium forecloses the PET process, which evokes a significant increase in fluorescence intensity. The fluorescence intensity of probes 1 and 2 with HOCl involves an ～18 and ～50‐fold enhancement compared with the respective responses from other reactive oxygen/nitrogen species (ROS/RNS) and low detection limits (30.9 nm for 1 and 4.5 nm for 2 ). Both probes show a very fast response with HOCl; emission intensity reached a maximum within 1 s. These probes show high selectivity for HOCl, as confirmed by confocal microscopy imaging when testing with RAW264.7 and MCF‐7 cells.