MPF—4荧光光谱仪波长系统的故障排除

本文介绍了MPF-4荧光光谱仪波长系统的故障分析及排除方法。叙述了波长的校准方法和步骤。     

3080E3型X射线荧光光谱仪故障排除方法

介绍了3080E3型X荧光光谱仪几例故障及排除方法.     

WFX—1E型原子吸收分光光度计的故障与修理

介绍了ＷＦＸ－１Ｅ型原子吸收分光光度计的故障与修理情况。     

PE 2000型等离子发射光谱仪故障排除方法两例

简述PE2000型等离子发射光谱仪的计算机和光栅驱动电路两个典型故障的排除方法。     

二阶导数红外分光光度法同时定量分析有机酸,酯

本选用有机酸、酯的－（Ｃ＝Ｏ）－红外特征峰作为分析峰，运用二阶导数法消除两分析峰之间的相互干扰，建立了用二阶导数红外分光光度法同时分析同一体系中有机酸、酯含量的新方法，其表观摩尔吸光系数分别为４．４４×１０＾４Ｌ·ｍｏｌ＾－１·ｃｍ＾－１，３．９４×１０＾４Ｌ·ｍｏｌ＾－１·ｃｍ＾－１，体系中的其它物质均不干扰测定。此方法操作简单、重现性好、选择性好，实样测定获得了满意的结果。     

ARL-SMS-2000全自动光谱仪的故障处理及日常维护

介绍了美国热电集团公司ARL SMS-2000全自动光谱仪所出现的突发故障及相应的处理办法,并对仪器的维护保养提出了具体要求.     

721型可见分光光度计常见故障及其检修

针对721型可见分光计的工作原理及操作经验,介绍了其在分析中常见故障及检修方法。     

红外分光光度法测定地下水中的石油类物质

采用红外分光光度法测定地下水中石油类物质。用四氯化碳萃取水中的石油类物质,将萃取物用硅酸镁吸附,脱除极性物质后进行测定。方法的检出限为0.014 mg/L,测定结果的相对标准偏差为0.65%~1.18%(n=l1)。用该方法对地下水样品进行测定并进行加标准回收试验,结果表明,地下水样品的加标回收率为84.0%~93.2%。该方法灵敏度高,操作简便、快速,可以满足地下水中石油类分析的要求。     

DV4型光谱仪两种故障的处理

美国ＢＡＩＲＤ公司生产的ＤＶ4光谱仪 ,在ＣＭＵ 2 0元素板上有 8个通道 ,元素板的总数由仪器中的光电倍增管总数决定 ,最多可分析 32个元素。我公司自 1986年以来 ,先后购进两台美国ＢＡＩＲＤ公司生产的ＤＶ4光谱仪。该仪器具有自动化程度高、选择性好、操作简单 ,分析速度快 ,可同时进行多元素定量分析 ;校准曲线线性范围宽 ,精度高 ,检出限低。我公司该仪器主要用于转炉、电炉钢包钢样的化学成分 (碳、硅、锰、磷、硫、镍、铬、铜、锡、钼、钒 )分析。在使用过程中出现过一些故障 ,均妥善地进行了处理并解决了存在的问题。以下为典型故…     

红外分光光度法测定粉尘中游离二氧化硅的含量

建立一种有效的红外分光光度法测定粉尘中游离二氧化硅含量,并对样品处理和曲线绘制方法进行了改进.游离二氧化硅含量在0～100.85 mg范围内与吸光度有良好的线性关系,相关系数r＝0.999 6.样品加标回收率为80.35%～92.77%,测定结果的相对标准偏差不大于5.06%(n=5).     

VD—1A型X射线衍射仪高压系统的故障分析及排除

本文以三个故障实例详细地叙述了岛津VD-1A型X射线衍射仪高压系统的故障分析和排除方法。     

One-Stage Monosubstitution in Cyclen - Two Novel Examples

Two new routes for alkylsubstituton of one in four amino groups in 1,4,7,10-tetraazacyclododecane (cyclen) are described, isomeric N-tris(hydroxy)butylcyclens 4 and 6 have been obtained in very good yields. Further carboxymethylation of other three amino groups afforded 10-tris(hydroxy)butyl-1,4,7-tris(carboxymethyl)cyclens 1 and 2.     

近红外光谱法快速分析罗红霉素中两种主要成分

针对大环内酯类抗生素罗红霉素制剂的近红外光谱分析,利用后向区间偏最小二乘算法(biPLS)对全光谱进行波长区间选择预处理,并将其压缩为主成分,再利用BP人工神经网络(BP-ANN)建立预测模型,对其中的主要成分罗红霉素和乳糖进行预测。通过这个方法建立的模型,可以有效地抵御因为噪声等偶然因素引起的瞬时扰动,并在有效减少建模所用的波长数和建模运算时间的同时,使所建模型能达到较高的预测精度。为近红外快速在线同时检测药物多组分含量提供了新的参考方法。     

难熔金属专用助熔剂在红外碳硫分析中的应用

采用难熔金属专用助熔剂对多种材料进行红外碳硫分析,考察了其与传统助熔剂空白值的比较.对不同样品的测定结果进行分析比较,发现难熔金属专用助熔剂的碳、硫空白值更低,样品燃烧充分,高温熔体流动性好.该助熔剂操作简便,分析速度快,适用范围较广.     

Direct Vibrational Energy Transfer in Monomeric Water Probed with Ultrafast Two Dimensional Infrared Spectroscopy

Vibrational relaxation dynamics of monomeric water molecule dissolved in d-chloroform solution were revisited using the two dimensional Infrared (2D IR) spectroscopy. The vibrational lifetime of OH bending in monomeric water shows a bi-exponential decay. The fast component (T₁=(1.2±0.1) ps) is caused by the rapid population equilibration between the vibrational modes of the monomeric water molecule. The slow component (T₂=(26.4±0.2) ps) is mainly caused by the vibrational population decay of OH bending mode. The reorientation of the OH bending in monomeric water is determined with a time constant of τ=(1.2±0.1) ps which is much faster than the rotational dynamics of water molecules in the bulk solution. Furthermore, we are able to reveal the direct vibrational energy transfer from OH stretching to OH bending in monomeric water dissolved in d-chloroform for the first time. The vibrational coupling and relative orientation of transition dipole moment between OH bending and stretching that effect their intra-molecular vibrational energy transfer rates are discussed in detail.     

Intermolecular Vibration Energy Transfer Process in Two CL-20-Based Cocrystals Theoretically Revealed by Two-Dimensional Infrared Spectra

Inspired by the recent cocrystallization and theory of energetic materials, we theoretically investigated the intermolecular vibrational energy transfer process and the non-covalent intermolecular interactions between explosive compounds. The intermolecular interactions between 2,4,6-trinitrotoluene (TNT) and 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) and between 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) and CL-20 were studied using calculated two-dimensional infrared (2D IR) spectra and the independent gradient model based on the Hirshfeld partition (IGMH) method, respectively. Based on the comparison of the theoretical infrared spectra and optimized geometries with experimental results, the theoretical models can effectively reproduce the experimental geometries. By analyzing cross-peaks in the 2D IR spectra of TNT/CL-20, the intermolecular vibrational energy transfer process between TNT and CL-20 was calculated, and the conclusion was made that the vibrational energy transfer process between CL-20 and TNTII (TNTIII) is relatively slower than between CL-20 and TNTI. As the vibration energy transfer is the bridge of the intermolecular interactions, the weak intermolecular interactions were visualized using the IGMH method, and the results demonstrate that the intermolecular non-covalent interactions of TNT/CL-20 include van der Waals (vdW) interactions and hydrogen bonds, while the intermolecular non-covalent interactions of HMX/CL-20 are mainly comprised of vdW interactions. Further, we determined that the intermolecular interaction can stabilize the trigger bond in TNT/CL-20 and HMX/CL-20 based on Mayer bond order density, and stronger intermolecular interactions generally indicate lower impact sensitivity of energetic materials. We believe that the results obtained in this work are important for a better understanding of the cocrystal mechanism and its application in the field of energetic materials.     

Microscopic Fourier Transform Infrared Characterization on Two Types of Spherulite with Polymorphic Crystals in Poly(heptamethylene terephthalate)

FTIR microspectrometry with in situ temperature variation and IR‐peak‐mapping capability, and POM characterization were used to study the crystal distribution in dual spherulites in poly(heptamethylene terephthalate). By tracing the crystalline IR bands of the α‐crystal and β‐crystal to get the crystal distribution, the techniques resolve that the ringed and ringless spherulites comprise α‐ and β‐crystals, respectively. In addition, temperature‐dependent IR analyses on the spots related to the two crystals also reveal the α‐ and β‐crystals melt at 98 and 104 °C, respectively. The ringed and ringless spherulites were proven to be correlated with the α‐ and β‐crystal forms, respectively.

     

Selectivity of Calixarene-bonded Silica-phases in HPLC: Description of Special Characteristics with a Multiple Term Linear Equation at Two Different pH-Values

Six different calixarene-bonded phases were characterized by analyzing 36 and 26 solutes at pH 3 and 7, respectively. Dolan and Snyder's multiple term linear equation was used to correlate retention factors k' to parameters of the solutes and columns. The column parameters have been related to molecular properties of the stationary phases and new suggestions were made for the interpretation of steric selectivity. Ionic and polar interactions have been found dependent on pH value, while steric interactions are less dependent and hydrophobic interactions remain unchanged. Distinct differences of the supported interactions were confirmed between the calixarene-bonded and the common alkyl-bonded silicas. By use of the parameters, values of k' can be estimated with an average deviation of 2.50 and 7.92% at low and neutral pH-value, respectively.     

Synthesis and Structure of BaPtIn3 and BaTl0.63In3.33. Two Contrasting Examples of Preferential Site Occupation in BaAl4‐Type Structures

The title compounds have been synthesised by high temperature means and characterized by single crystal X‐ray diffraction analysis. The compounds crystallize in the tetragonal structure type of BaAl₄, I4/mmm, Z = 2 (a = 4.8130(7), 5.0196(8) Å; c = 11.669(2), 11.900(3) Å for BaPtIn₃ and BaTl_0.63In_3.37, respectively).Platinum and thallium randomly substitute for 50 % of the In in the apical 4e and for 30 % in the basal 4d positions in the two networks, respectively. Consistent with both size and relative electronegativity factors, the basal positions in BaAl₄‐type structure are appropriate for substitution by dimensionally and chemically similar atoms (Tl), which is different from the apical sites in which electronegativities or bond strengths are more important (Pt).