红外光谱法定性分析三元乙丙橡胶的制样方法探讨

分别采用三种方法制备三元乙丙橡胶制品试样,并用红外光谱法对其定性分析.结果表明,相比硫化胶溶解制膜法,用溶剂抽提后裂解制样和直接裂解制样法制备的试样进行红外光谱分析均能得到与GB/T7764-2001《橡胶鉴定红外光谱法》吻合的标准.从实验的经济快速考虑,可以采用直接裂解制样法定性分析三元乙丙橡胶制品,且分析结果可靠.     

拉曼雷达测量大气二氧化碳浓度回波信号误差分析

拉曼雷达探测二氧化碳的后向散射回波信号十分微弱,有效分析信号的误差非常重要. 从理论上分析了拉曼激光雷达探测二氧化碳气体的回波信号误差的计算方法,推导计算了二氧化碳浓度信号的混合比,得到了影响信号误差的3种因素,并对各因素进行了理论计算,从实验上对信号误差进行了数据验证. 将理论值与实验数据进行对比,确定信号采集过程中造成的数据误差小于10%,并随距离的增加而增加;大气透过率相对函数的误差约为2%;标定常数的误差小于5%.      

枸杞产地的小波变换红外光谱的聚类分析鉴别

采用傅里叶变换红外光谱(FTIR)对不同枸杞样品产地进行鉴别.常规预处理方法和小波变换对红外光谱原始数据进行了预处理.对比常用的窗口移动平滑预处理、标准正态变换以及多元散射校正,说明小波变换是一种有效实用的光谱预处理方法.对已预处理后的红外光谱数据进行主成分分析和聚类分析,结果 18份枸杞样品聚为主产地和非主产地两大类,取得了较满意的分类效果.这种红外光谱技术结合聚类分析法被证明是可靠的,可作为枸杞产域鉴别的一种现代化方法.     

Characterization of cocrystals formed by grinding amino acids through terahertz time-domain spectroscopy

In this paper,we used terahertz time-domain spectroscopy(THz-TDS)over a range of 0.3–2.5 THz to investigate the formation of solid-state cocrystals of amino acids,formed by grinding mixtures of two different kinds of amino acids.For comparison,we prepared dual-layer samples,combined by pressing two single-component pellets together without grinding.In the ground-mixture samples,some extra absorption peaks appeared,different from the characteristic peaks of the pure components,but these peaks did not appear in the dual-layer samples.Thus,these extra absorption peaks in the THz range are unique features of cocrystals.From our results,we believe that THz-TDS is a promising technique to characterize cocrystals.     

Influence of the amplitude ratio between two terahertz pulses on two-dimensional spectroscopy

The influence of the amplitude ratio between the two THz pulses on two-dimension THz spectroscopy （2DTS） has been studied theoretically via a classical method in which the expressions for the second-order nonlinearity were derived using perturbation approach, and the THz pulses were not treated as a delta function. Three types of nonlinear sources i.e., anharmonicity, nonlinear damping, and nonlinear coupling, are considered in a single mode system. The simulation results demonstrated that the amplitude ratio had a notable influence on the 2DTSs, and different sources have different influences. This study is promising for guiding future experiments.     

High-energy ion treatments of amorphous As40Se60 thin films for optical applic ations

The treatment of 100 MeV Ag swift-heavy ion(SHI) irradiation with five different fluences(3 1010, 1 1011, 3 1011, 1 1012, and3 1012ions/cm2) was used to design optical and structural properties of amorphous(a-) As40Se60 chalcogenide thin films. Swanepoel method was applied on transmission measurements to determine the changes in optical bandgap, Tauc parameter and linear optical parameters, i.e., linear optical absorption, extinction coefficient and linear refractive index. Dispersion of the material was determined by Wemple–DiDomenico relation.Changes in nonlinear optical parameters of third-order optical susceptibility and nonlinear refractive index were determined using semi-empirical relations. Changes in surface morphology of the films were investigated using SEM observation, which indicated that fluence 3 1012ions/cm2was upper threshold limit for these films for ion treatment. It is observed that optical bandgap reduces from 1.76 eV to 1.64 eV, and nonlinear refractive index increases from 1.31 10 10[esu] to 1.74 10 10[esu]. Linear refractive index initially increases from 2.80 to 3.52(for fluence3 1010ions/cm2) and then keeps decreasing. The observed changes in optical properties upon irradiation were explained in terms of structural rearrangements by Raman measurement. The study was compiled with the previous literature to propose SHI as an effective optical engineering technique to achieve desired changes according to the need of optical/photonic applications.     

Au@SiO2颗粒对石墨烯量子点拉曼信号的增强作用

采用金纳米颗粒包覆了一层二氧化硅壳层作为实验材料,利用该核壳材料增强石墨烯量子点的拉曼信号,并实现了单颗粒增强.实验中,二氧化硅的厚度可以通过反应时间得到控制,该壳层可以增强金纳米颗粒的化学和物理稳定性.本文方法与使用纯金纳米颗粒增强石墨烯量子点拉曼信号相比,其拉曼信号强度增强了20%以上.     

VO2(A)纳米杆的水热合成、生长机理及光学特性

用V2O5和草酸作为初始原料,在水热条件下合成了VO2(A)纳米杆.通过改变初始的V2O5与草酸摩尔比以及反应时间制备纯相VO2 (A).样品的元素组成、微结构及光学性能分别被X射线光电子能谱(XPS)、X射线衍射(XRD)、扫描电镜(SEM)、差示扫描量热法(DSC)和傅里叶变换红外光谱(FT-IR)表征.实验结果表明合成VO2 (A)的最佳条件为:反应温度230℃、保温24 h以及V2O5对草酸摩尔比为1∶1.5.结合XRD数据与SEM图像,提出一个转变、自组装和重结晶过程解释了VO2 (A)纳米棒的形成过程.     

Electrochemical and spectroscopic study of interfacial interactions between chalcopyrite and typical flotation process reagents

Comparative voltammetry and differential double-layer capacitance studies were performed to evaluate interfacial interactions between chalcopyrite (CuFeS₂) and n-isopropyl xanthate (X) in the presence of ammonium bisulfite/39wt% SO₂ and caustic starch at different pH values. Raman spectroscopy, Fourier transform infrared (FTIR) spectroscopy, contact angle measurements, and microflotation tests were used to establish the type and extent of xanthate adsorption as well as the species involved under different mineral surface conditions in this study. The results demonstrate that the species that favor a greater hydrophobicity of chalcopyrite are primarily CuX and S0, whereas oxides and hydroxides of Cu and Fe as well as an excess of starch decrease the hydrophobicity. A conditioning of the mineral surface with ammonium bisulfite/39wt% SO₂ at pH 6 promotes the activation of surface and enhances the xanthate adsorption. However, this effect is diminished at pH ≥ 8, when an excess of starch is added during the preconditioning step.     

高温超导体YBaCuO光掺杂效应的正电子寿命谱研究

报道了YBaCuO高温超导体进行光掺杂的基本情况,提供了正电子寿命与光掺杂量之间的变化关系,讨论了光掺杂机理,并将实验结果与理论模型进行了对比.