空心阴极放电沉积氮化碳薄膜的结构和成键性质

利用空心阴极放电等离子体源在Si(100)衬底上沉积了氮化碳薄膜.用XRD,SEM,XPS及拉曼和红外吸收光谱对薄膜的结构、成分和化学键等进行了研究.XRD分析表明,制备的氮化碳薄膜为非晶结构.XPS分析证实了薄膜中以C—C,sp2CN和sp3CN键为主,并得出薄膜中的氮碳比为0.71,而sp3—CN相的含量也达到了0.39.拉曼和红外吸收光谱的结果也与XPS分析的键态结果一致.     

Temperature dependence of photoluminescence and electroluminescence of ZnS:Mn crystals

By means of comprehensive analysis of the temperature dependences of the photoluminescence for ZnS:Mn crystals, we have observed persistent changes in the intensity, shape, and position of the maximum in the emission spectrum associated with changes in the immediate environment of the manganese luminescence centers. We have also observed inflection points on the voltage vs. brightness characteristics of the samples, the position of which depends on the frequency of the exciting voltage and the temperature. The observed dependences are explained using concepts describing the mechanisms of pre-breakdown luminescence. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 631–636, September–October, 2006.     

Experimental and theoretical studies of electronic energy states of methyl benzoate derivatives

Spectroscopic steady state studies of four monosubstituted derivatives of methyl benzoate dissolved in methylcyclohexane (McH), tetrahydrofuran (THF), ethanol (EtOH) and isopentane-diethyl ether mixture (IP-DE) have been performed at 293 and 77 K. The determined electronic energy values and oscillator strengths are compared with those obtained from quantum chemical calculations. Good agreement between experimental and theoretical energy values is noted. The average value is smaller than 5 percent. A reasonable agreement is noted between intensities of separated bands and oscillator strength of corresponding transitions. The relative ratio of fluorescence to phosphorescence intensity I_fl/I_ph of ortho-substituted compounds dissolved in non-polar, polar and protic solvents is higher than that of the para-substituted derivatives of methyl benzoate. The spectroscopic studies show that methyl ortho-hydroxy benzoate in the excited state S₁ forms H-bonded dimers in the solvents used. At 77 K the dimer fluorescence dominates the phosphorescence emission. The long wavelength absorption band (C) of amino-substituted methyl benzoates consists of two transitions in agreement with our theoretical calculations and a suggestion made by Shabestary and El-Bayoumi [N. Shabestary, M.A. El-Bayoumi, Chem. Phys. Lett. 106 (1984) 107].     

EPR谱图模拟软件EasySpin的图形用户界面设计

EasySpin是一款较为流行的电子顺磁共振（EPR）谱图模拟和拟合软件,LabVIEW是一种图形化编程语言开发环境．本文介绍了一款使用LabVIEW为EasySpin设计的图形用户界面LV-EasySpin．LV-EasySpin提供了一种直观的操作方法来实现连续波EPR多组分波谱的可视化模拟和拟合．本文辅以各种模式下的实例进行说明,阐述了LV-EasySpin的设计思路与实现方案,最终希望具有简洁、易操作界面的LV-EasySpin可以降低用户使用EasySpin分析EPR谱图的难度．     

Experimental research on flame spectra of methane-coal dust explosions

The significance of experimental research on flame spectra of methane-coal dust explosions is explained. Weak explosions of methane-coal dust-air mixtures were carried out in a large-scale tube of Ø 200 cm×2900cm with one end open, and the absolute radiation intensities as well as their variation under different conditions for characteristic wavelengths of 0.8875, 1.000, 1.505, 2.801, and 4.346μm were obtained by using small angle of view and a multichannel detector developed by us. The experimental results are discussed and compared with those published abroad. Based on the absolute radiation intensity measured at wavelength 4.346μm and the selected blackbody radiation model, the temperature of explosion flame was determined. The results obtained are not only of great practical importance to the industry but may also be used in the study of flame and chemical kinetics.     

A Galerkin Approach for Power Spectrum Determination of Nonlinear Oscillators

A numerical method to estimate spectral properties of nonlinear oscillators with random input is presented. The stationary system response is expanded into a trigonometric Fourier series. A set of nonlinear algebraic equations, solved by Newtons method, leads to the determination of the unknown Fourier series coefficients of single samples of the response process. For cubic polynomial nonlinearities, closed-form expressions are used to find the nonlinear terms at each step of the solution scheme. Further, a simple procedure yields an approximation of an arbitrary nonlinearity by a cubic polynomial. Power spectral density estimates for the response process are constructed by averaging the square modulus of the computed Fourier coefficients over various samples or by means of well-established smoothing techniques of spectral analysis. Two applications are presented illustrating the effectiveness of the method as compared to statistical linearization and digital Monte-Carlo simulation.     

How Van der Waals Interactions Influence the Absorption Spectra of Pheophorbide a Complexes: A Mixed Quantum–Classical Study

The computation of dispersive site energy shifts due to van der Waals interaction (London dispersion forces) was combined with mixed quantum–classical methodology to calculate the linear optical absorption spectra of large pheophorbide a (Pheo) dendrimers. The computed spectra agreed very well with the measurements considering three characteristic optical features occurring with increasing aggregate size: a strong line broadening, a redshift, and a low‐energy shoulder. The improved mixed quantum–classical methodology is considered a powerful tool in investigating molecular aggregates.     

Identification of hydroxymethylpyrazines using mass spectrometry

Pyrazines are well‐known natural products that are present in bacterial odours and food flavouring agents and are used as insect pheromones. Recently, a number of hydroxymethylpyrazines have been identified as thynnine wasp pheromones and orchid semiochemicals that are essential for pollination in sexually deceptive plants. These compounds are present in low amounts in complex blends, making GC–MS (including high‐resolution techniques) the method of choice for their structure elucidation. We report the EI mass spectra for 14 representative compounds and have found that based on characteristic fragmentations, it is possible to distinguish between different positional isomers of hydroxymethylpyrazines. The presence or absence of either [M ? 17]⁺, [M ? 18]^+· or [M ? 19]⁺ fragment species provides characteristic information to allow the distinction between the different isomers. Considering the importance of pyrazines as a group of bioactive natural products, and the recent findings of biological activity for hydroxymethylpyrazines, our results presented here will aid the identification of these compounds in other biological systems. Copyright © 2015 John Wiley & Sons, Ltd.     

Clustering of sulfamic acid: ESI MS and theoretical study

Sulfamic acid has wide application in industry and has been suggested to act as an effective nucleation agent for the formation of aerosols and cloud particles. From the point of view of the role that sulfamic acid may play in aerosol formation, the study of its homoaggregation is important. Gas phase clustering study was performed for sulfamic acid H₃N·SO₃, (ASA), from water and methanol–water solutions, by help of a TOF‐Q spectrometer equipped with electrospray ionization source, in the negative‐ion mode. The structure and stability of the (H₃N·SO₃)_n and [(H₃N·SO₃)_n‐H]^? (n = 1–6) were studied using DFT/B3LYP/aug‐cc‐pVDZ method. The ESI MS study evidenced that both singly and doubly charged clusters are formed when the acids are electrosprayed from water solutions; they may be described as [(H₃N·SO₃)_n‐zH]^z? where z = 1 or 2. The largest identified clusters are built of 20 monomers. The theoretical studies showed that formation of higher order (ASA)_n aggregates in the gas phase is energetically profitable. In contrast with the gas phase, aqueous solution does not favor the formation of (ASA)_n aggregates. The study led to the conclusion that the ASA clusters are formed in the gas phase under the experimental conditions of the mass spectrometer. A hypothetical mechanism concerning the formation of the doubly negatively charged anionic aggregates is discussed. The obtained data suggest that small (NH₃·SO₃)_n aggregates may also contribute to formation of aerosols in heavily polluted atmospheres with relatively large NH₃ concentration. Copyright © 2015 John Wiley & Sons, Ltd.     

Ratiometric detection of Raman hydration shell spectra

The micro‐structure of hydration shell of solute in water is significant for understanding the properties of aqueous solutions. However the spectra of hydration shell are difficult to be obtained. Herein, a novel Raman ratio spectra, which is obtained through dividing the Raman spectra of aqueous solutions from the spectrum of water, was applied to deduce the spectra of hydration shell of organic (acetone‐D6) and inorganic compounds (NaNO₃, NaSCN, NaClO₄, Na₂SO₄, NaCl) in water. Those spectra of the hydration shell were employed to study the micro‐structures of the first hydration shells of anions, the number of water molecules in the first hydration shell of free anions and acetone‐D6, and the aggregation behavior of ions in the concentrated aqueous NaNO₃. The number of water molecules in the hydration shell was supported by our molecular dynamic simulations. The Raman ratio spectra can be widely employed to obtain the spectra of the first hydration shell, and it is helpful to understand the micro‐structure of aqueous solutions. Copyright © 2016 John Wiley & Sons, Ltd.