Effect of local structure on electron paramagnetic resonance spectra for trigonal [Cr(H_2O)_6]^(3+) coordination complex in the sulfate alums series:a ligand field theory study

A simple theoretical method is introduced for studying the interrelation between electronic and molecular structures.By diagonalizing the 120 × 120 complete energy matrices,the relationships between zero-field splitting （ZFS） parameter D and local distortion parameter △θ for Cr^3＋ ions doped,separately,in α- and β- alums are investigated.Our results indicate that there exists an approximately linear relationship between D and △θ in a temperature range 4.2-297 K and the signs of D and △θ are opposite to each other.Moreover,in order to understand the contribution of spin-orbit coupling coefficient ζ to ZFS parameter D,the relation between D and ζ is also discussed.

A study on resonance Rayleigh scattering spectra of Humic Acid (HA)

This paper deals with the influences of pH, acidity and ionic intensity of the solutions on the resonance Rayleigh scattering spectra and fluorescence spectra of humic acid. When the pH value is low and the acidity and ionic intensity are high, the resonance Rayleigh spectra and fluorescence spectra both show a tendency of increasing, though the former's intensity is much higher. In combination with the transmission electron microscope data, the factors leading to the occurrence and enhancement of the resonance Rayleigh scattering spectra of humic acid were explored. It is considered that particle enlargement caused by aggregation, the increase of heterogeneity, the increase of hydrophobility, the formation of interface, etc., are the factors leading to the occurrence and enhancement of the resonance Rayleigh scattering spectra of humic acid. As the intensity of the resonance Rayleigh scattering spectra of humic acid is much higher, resonance Rayleigh scattering spectroscopy can be used as a newly developed spectrum technology, which is more sensitive and simpler, to study humic acid and its complicated behaviors.

Resonance luminescence spectra of selenium （Ⅳ）—iodide—rhodamie B sy

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Electron paramagnetic resonance studies of the chelate-based ionic liquid in different solvents

The electron paramagnetic resonance spectra of the chelate-based ionic liquid[C_(10)mim][Cu(F_6-acac)_3]in different solvents have been obtained at 120 K.It was found that the values of the^(63)Cu hyperfine coupling constants(A_(IL))of[C_(10)mim][Cu(F_6-acac)_3]in molecular solvents were from 116 to 180 Gauss.Moreover,the A_(IL)values in general ionic liquids are more complicated,and two sets of peaks can often be observed in their electron paramagnetic resonance spectra.Based on the Kamlet-Taft parameters,relative permittivity,the experimental results were discussed in terms of solvation effect and coordination of the solvents.

X-Ray Diffraction, Electron Paramagnetic Resonance and Optical Absorption Study of Bauxite

The bauxite mineral obtained from Araku, Vishakapatnam district of Andhra Pradesh, India is used in the present work. Structural characterization was performed by X-ray diffraction (XRD). The mineral was found to be gibbsite in phase. The transitional metal ions present were investigated using electron paramagnetic resonance (EPR) and optical absorption spectra. The EPR results suggest that Fe3+ has replaced Al3+ in the unit cell of bauxite. The optical absorption spectrum is due to Fe3+ which indicates that it is in distorted octahedral environment. The near-infrared (NIR) spectrum is due to water fundamentals and combination overtones, which confirm the formula of the compound. The impurities in the mineral are identified using spectroscopic techniques.

Influence of pressure effect on Fermi resonance in binary solution

The Fermi resonance behaviours of the two groups of binary solutions -- pyridine and methanol, benzene and carbon tetrachloride, under different pressures are investigated according to their Raman spectra. The effect of pressure on Fermi resonance in binary solution differs significantly from that in pure liquid. In a binary solution, with the intermolecular distance shortening, the intermolecular interaction potential increases, the shift rates of the Raman spectral lines increase, the spectral line splitting occurs ahead of that in pure liquid, and the wavenumber separation A0 between the unperturbed harmonic levels shifts more quickly, too. The Fermi resonance parameters, the coupling coefficient W and the intensity ratio R of the two Raman bands, decrease rapidly with pressure increasing, and the pressure at which Fermi resonance phenomenon disappears is much lower than that in pure liquid, especially in the solution whose molecules are of the same polarity. This article is valuable in the identification and the assignment of spectral lines under high pressure, as well as the study of high pressure effect, intermolecular interaction, and solvent effects in different cases, etc.

常压下酸催化多元醇液化纤维素反应机理的研究

开发农林废弃物高值化利用路径与“深入推进能源绿色低碳转型”国家重大战略需求高度契合。实验探索农业废弃物玉米秸秆中纤维素组分常压酸(H3PO4)催化多元醇[丙二醇(PG)与二甘醇(DEG)混合液]液化反应路径为研究目标,了解酸催化多元醇作用条件下的木质生物质液化反应机理。采用傅里叶红外光谱(FTIR)、凝胶渗透色谱(GPC)、核磁共振波谱(NMR)及热重分析(TGA)对不同反应时间下纤维素液化所得生物油的化学基团、分子量及其分布、分子结构、热解等进行了分析。FTIR检测表明,不同反应时间所得生物油具有相似FTIR特征;液化初期,纤维素降解生成了较多的烃类、醚类和含羰基化合物;液化后期,纤维素中的糖类降解产物、羟基或烯烃与PG/DEG反应生成了难溶于1,4-二氧六环的有机物。GPC分析表明,随着液化的进行,纤维素分子链发生断裂程度加剧,降解生成低分子量(LMW)物质越来越多,降解反应占主导地位;而当反应时间达到某一值时,其降解产物与PG/DEG发生聚合反应产生越来越多的大分子量物质,使生物油的分子量不再降低,即聚合反应占主导地位。^(1)H-和^(13)C-NMR表明,纤维素在液化作用下发生降解使得分子链断裂,仍保留了部分葡萄糖单元结构;随着液化反应的进行,这些结构单元再次发生转化产生LMW化合物;反应继续进行时,这些产物之间或与PG/DEG之间可进行聚合反应,形成结构趋于一致、性质逐渐稳定的新物质。TGA分析结果:生物油中含有70%~85%碳数小于25和5%~10%碳数高于25的化合物,最终残炭率随着反应时间的延长先降低再升高。实验通过研究纤维素在多元醇液化过程中的结构变化,揭示其液化的反应历程,为探索秸秆全组分的液化机理奠定理论基础。

环烯烃共聚物和均聚物性能对比

环烯烃聚合物具有高耐热性、高韧性、高透明性和高尺寸稳定性,已成为玻璃材料的理想替代品,并在光学和医疗领域展现出广泛的应用前景。为了揭示环烯烃聚合物化学结构与性能之间的内在联系,为新材料的研发与定制奠定基础,通过体视显微镜、接触角测试仪、紫外-可见分光光度计、凝胶渗透色谱仪、傅里叶变换红外光谱仪、热重分析仪、差示扫描量热仪、核磁共振波谱仪等对两种典型的环烯烃聚合物材料—环烯烃共聚物(COC)和环烯烃均聚物(COP)的性质进行了详细的对比。结果显示,COP的透光率比COC高,COP疏水性比COC的强,COC的重均分子量和数均分子量比COP的大,分子量分布稍宽;COP的红外特征吸收峰在920 cm^(-1)和815 cm^(-1)处,COC的红外特征吸收峰在1141,773,715 cm^(-1)处;COC和COP的初始分解温度和最大分解温度基本一致,且表现出一个玻璃化转变温度,没有熔融峰的出现,这说明COC和COP都是无定形的;核磁共振碳谱显示COC的化学位移δ在32~36以及46.5~50处出现特征峰,而COP的化学位移δ在51~52和46处出现特征峰。

Ab initio potential energy surface and anharmonic vibration spectrum of NF_(3)^(+)

Potential energy surfaces(PESs), vibrational frequencies, and infrared spectra are calculated for NF_(3)^(+) using ab initio calculations, based on UCCSD(T)/cc-p VTZ combined with vibrational configuration interaction(VCI). Based on an iterative algorithm, the surfaces(SURF) program adds automatic points to the lattice representation of the potential function, the one-dimensional and two-dimensional PESs are calculated after reaching a convergence threshold, finally the smooth image of the potential energy surface is fitted. The PESs accurately account for the interaction between the different modes, with the mode q_(6) symmetrical stretching vibrations having the greatest effect on the potential energy change of the whole system throughout the potential energy surface shift. The anharmonic frequencies are obtained when the VCI matrix is diagonalized. Fundamental frequencies, overtones, and combination bands of NF_(3)^(+) are calculated, which generate the degenerate phenomenon between their frequencies. Finally, the calculated anharmonic frequency is used to plot the infrared spectra.Modal antisymmetric stretching ν_(5) and symmetric stretching ν_(6) exhibit a phenomenon of large-intensity borrowing. This study can provide data to support the characterization in the laboratory.

Coupled resonator-induced transparency on a three-ring resonator

The coupled resonator-induced transparency （CRIT） phenomenon, which is analogous to electromagnetically induced transparency in atomic systems, can occur in an original integrated optical resonator system due to the coherent interference of the coupled optical resonators. The system was composed of three ring resonators on silicon, each with the same cavity size, and the optical coupling to the input and output ports was achieved using grating with a power coupling efficiency of 36%. A CRIT resonance whose spectrum shows a narrow transparency peak with a low group velocity was demonstrated. The quality factor of the ring resonator can attain a value up to 6x 104, and the harmonic wavelength can be controlled by adjusting the temperature. The through and drop transmission spectra of the resonator are reconciled well with each other and also consistent well with the theoretical analysis.

Isolation,Purification and Spectral Characteristics of Soluble Guanylate Cyclase from Bovine Lung

We isolated and purified high purity and high activity soluble Guanylate cyclase(sGC) from bovine lung. The electronic absorption and resonance Raman spectra of the ferrous and ferric forms of sGC were recorded. In the ferrous state of sGC, the electronic absorption spectra showed a sharp peak at 431 nm and a single broad peak in the α/β region at 559 nm. The resonance Raman spectra of sGC(ferrous) showed a stronger band at 1357 cm -1 and a single peak at 1473 cm -1 . For the ferric form of sGC, the Soret band was at 390 nm and resonance Raman peak was at 1375 cm -1 . These spectra show that the heme iron of the ferrous and ferric sGC are all 5 coordination and high spin.

Angle-dependent spin wave spectra of permalloy ring arrays

We investigated the angle-dependent spin wave spectra of permalloy ring arrays with the fixed outer diameter and various inner diameters by ferromagnetic resonance spectroscopy and micromagnetic simulation.When the field is obliquely applied to the ring,local resonance mode can be observed in different parts of the rings.And the resonance mode will change to perpendicular spin standing waves if the magnetic field is applied along the perpendicular direction.The simulation results demonstrated this evolution and implied more resonance modes that maybe exist.And the mathematical fitting results based on the Kittel equation further proved the existence of local resonance mode.

Spectral data analysis and identification of Thymopentin

AIM: To provide a basis for nuclear magnetic resonance (NMR) characterization of polypeptide compounds. METHODS: The 1 H, 13 C NMR and 2D NMR spectra were used to characterize Thymopentin. By using infrared(IR), ultraviolet(UV), mass spectrometry(MS) techniques, along with 1 H-1 H correlation spectrometry (COSY) and distorsionless enhancement by polarization transfer (DEPT), the proton and carbon-13 spectra were assigned completely. RESULTS: The Thymopentin was characterized based on the methods described above. CONCLUSION: The target molecule is confirmed and the structure is identified.

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.

Absorption and Rayleigh scattering and resonance Rayleigh scattering spectra of [HgX_2]_n nanoparticles

The composition and existing species of the reaction production of Hg2+ and X- (X= Cl, Br and l) under different conditions, and their absorption, Rayleigh scattering (RS) and resonance Rayleigh scattering (RRS) spectra have been studied. The results show that the products exist in the form of nanoparticles as [HgX2]n aggregates under suitable conditions, and their average diameters increase with the increase of X- diameters. The diameters of [HgCl2]n [HgBr2]n and [Hgl2]n are less than 4 nm, equal to 9 nm and 70 nm respectively. There are bathchromic shifts gradually with the increase of X- diameters in their absorption spectra. The absorption bands of [HgCl2]n and [HgBr2]n locate at ultraviolet region. However, the absorption band of [Hgl2]n is obvious in visible light region. Among three particles, only [Hgl2]n exhibits a strong RRS and its scattering peak is at 580 nm. The main reasons leading to the enhancement of resonance scattering are the large size of nanoparticle, the formation of the interface and the location of light scattering in the absorption band. There are three important factors affecting resonance scattering spectrum: the quanta colored effect and molecular absorption spectrum of [Hgl2]n nanoparticle as well as instrumental factors which mainly include the light source's emission spectral characteristics and the signal response curve of detector.

Study on the absorption and fluorescence and resonance Rayleigh scattering spectra of Cu (II)-fluoroquinolone chelates with erythrosine and their applications

In pH 4.2-5.0 Britton-Robinson buffer solution medium, fluoroquinolone antibiotics (FLQs), such as ciprofloxacin (CIP), norfloxacin (NOR), ofloxacin (OF), levofloxacin (LEV), lomefloxacin (LOM), and sparfloxacin (SPA), react with Cu (II) to form chelate cations, which further bind with erythrosine to form the ion association complexes. They can result in the changes of the absorption spectra. Simultane- ously, erythrosine fades obviously and the maximum fading wavelength is located at 526 nm. The fad- ing reactions have high sensitivities. Thus, new spectrophotometries of determination for these drugs are developed. The ion-association reactions result in the quenching of fluorescence, which also have high sensitivities. The detection limits for six antibiotics are in the range of 7.1-12.2 μg·L?1. Furthermore, the reactions can result in the enhancement of resonance Rayleigh scattering (RRS). The maximum scattering peaks of six ion-association complexes are located at 566 nm, and there are two small RRS peaks at 333 nm and 287 nm. The detection limits for fluoroquinolone antibiotics are in the range of 1.70 -3.10 μg·L?1 for RRS method. Among the above three methods, the RRS method has the highest sen- sitivity. In this work, we investigated the spectral characteristics of the absorption, fluorescence and RRS, the optimum conditions of the reactions, and the properties of the analytical chemistry. In addi- tion, the mechanism of reactions were discussed by density function theory (DFT) and AM1 methods.

Absorption, fluorescence and resonance Rayleigh scattering spectral characteristics of interaction of gold nanoparticle with safranine T

The interaction between gold nanoparticle and safranine T (ST) has been studied with resonance Rayleigh scattering (RRS) spectra, absorption and fluorescence spectra. In the pH 5 solution, citrate [(H2L)2?] self-assembles on the surface of positively-charged gold nanopar-ticle, which results in the [(Au)n(H2L)m]x? complex. In other words, one of carboxylate oxygens in (H2L)2? moves inward and combines with gold nanoparticle. The other carboxylate oxygens moves outward to form a supermolecular complex anion with x negative charges. Then by virtue of electrostatic attraction, hydrophobic force and charge transfer action, the complex anion binds with ST cation to form a new ion-association complex. Here (H2L)2? acts as a bridge. The forma-tion of the complex results in the significant enhancement of RRS intensity, the appearance of new RRS spectrum, the red shift of plasma absorption band of gold nanoparticle as well as the decrease in the absorbance and fluorescence quenching for safranine T. In this work, the inter-action between gold nanoparticle and ST on the RRS, absorption and fluorescence spectra has been investigated. The reason why RRS intensity increases greatly and the reaction mechanism have been inquired. The results show that RRS spectra can not only be used to study nanopar-ticle and reaction product, but also are a sensitive means to characterize and detect nanoparti-cles.

Structural characterization and immunostimulatory activity of a water-soluble polysaccharide from abalone(Haliotis discus hannai Ino)muscle

A water-soluble polysaccharide from abalone muscle(AMPP)was isolated.The contents of carbohydrate,protein,uronic acid,and sulfate in AMPP were 83.5%,0.5%,2.7%,and 2.6%,respectively.High-performance liquid chromatography analysis indicated that AMPP was homogeneous and had an average molecular weight of approximately 3.2 kDa.The main monosaccharides of AMPP were glucose(Glc)and mannose with a molar ratio of 99.7:0.3.The structural characteristics of AMPP were elucidated through methylation analysis,Fourier transform infrared spectroscopy,and nuclear magnetic resonance spectroscopy.The linkages of AMPP consisted of terminal,1,4-linked,1,6-linked,and 1,4,6-linked Glcp with a molar ratio of 3.1:7.2:1.0:2.5.In one repeat unit of the proposed AMPP structure,the backbone chain was composed of eight 1→4 glycosidic bonds and one 1→6 glycosidic bond,with three branch chains linked by 1→6 glycosidic bond.In addition,AMPP was found to possess potent immunostimulatory activity via rising phagocytosis of RAW264.7 cells and promoting secretion of TNF-α.

A systematic analysis of the radial resonance frequency spectra of the PZT-based (Zr/Ti=52/48) piezoceramic thin disks

In this paper,both the ID radial mode and the equivalent circuit of a piezoceramic disk resonator were theoretically analyzed based on IEEE standards.And then,the radial resonance frequency spectra of the PZT-based(Nb/Ce co-doped Pb(Zro.s2Ti0.48)O3,abbreviated as PZT-NC)piezoceramic circular disks were measured by an impedance analyzer.A set of resonance frequency spectra including six electrical parameters:Z,R,X,Y,G,and B,were used for making a value distinction between three possible resonance frequencies,and between three possible antiresonance frequencies.A new-form Nyquist diagram was depicted to describe the position relations of these characteristic frequencies.Such a complete resonance frequency spectrum was used to perform the accurate calculation of some material constants and electromechanical coupling parameters for the PZT-NC piezoceramics.Further,the frequency dependence of the AC conductive behavior of the specimen was characterized by the complex impedance measurement.The values of AC conductivity at resonance/antiresonance were deduced from the equivalent circuit parameters.Moreover,the Van Dyke circuit model was assigned to each element contribution and the simulated curves showed a nice fitting with the experimental results.Finally,an additional impedance analysis associated with resonance frequency calculation revealed a complicated coupled vibration mode existing in the annular disk specimen.

低场核磁共振技术在槟榔水分测定中的应用

为了准确和高效评估槟榔的新鲜程度,利用低场核磁共振技术对干燥过程中的槟榔进行成像及驰豫时间(T_(2))采集,研究槟榔干燥过程中水分迁移及水分状态变化规律,建立一种快速无损检测槟榔含水率的方法。结果表明,槟榔鲜果中共存在三种水分状态:自由水、不易流动水和结合水,而自由水占比90%以上。在干燥过程中,自由水含量快速降低,结合水含量占比逐渐上升,槟榔水分含量与驰豫时间(T_(2))反演谱图总峰面积呈显著正相关,拟合方程为y=164.9x+62.686(R^(2)=0.9969);槟榔水分含量与衰减曲线首峰点值呈显著正相关,拟合方程为y=165.58x+19.892(R^(2)=0.9979)。经过验证模型,槟榔含水率在20%以上时,真值与拟合值相对误差控制在5%以内,可用低场核磁共振技术对槟榔含水率进行快速无损检测。