差谱NOE的应用

本文介绍了核磁共振差谱NOE技术及二个应用实例。     

差谱NOE的应用(Ⅱ)

本文用核磁共振差谱NOE技术研究了三个小分子化合物的甲氧基构象及几个羟基取代香豆素化合物的结构并得出差谱NOE不能考查螯合OH邻位有无取代基的结论。     

旋转坐标系同核NOE差谱

提出一种测定旋转坐标系NOE差谱的NMR技术.与通常的NOE技术相比,其特点是:应用范围较广,可节省测定时间,NOE信号为纯吸收型,可测定NOE的大小,并且可得到某些谱峰高度重叠,采用通常技术难于测定的有机化合物的NOE谱.     

宽谱段红外消热差光学系统设计

宽谱段红外光学系统可以获取宽谱段的图像信息并增大目标信息获取程度。从红外光学系统的简洁性出发,对红外光学系统进行设计,系统仅由4片球面透镜组成,实现了4.4 m~8.8 m波段清晰成像, F#为2.68,达到了100%的冷光阑效应。采用被动消热差方式通过合理选择镜片材料及公式推导最终实现了各个波段内的消热差,镜筒材料为钛合金,透镜采用硒化锌（ZnSe）,锗（Ge）及硫化锌（ZnS）材料,给出20 lp/mm处系统在各个波段在-40 ℃~60 ℃的工作温度下的调制传递函数（MTF）,以及各个波段下的光学系统畸变值。实验结果表明:设计的宽谱段红外光学系统结构简单,满足设计要求。     

CO2激光自差信号的功率谱研究

利用10MHz高速数据采集和处理系统分析了激光自差信号的功率谱.其功率谱分布在低频区;当多普勒频移增大时,自差信号的带宽增加,功率谱对频率的积分收敛于信号的功率.实验结果还表明,利用高速数据采集和处理的分析方法,比频谱分析仪有更多的优点.     

差谱技术用于塑料焊接剂的结构鉴定

本文利用ＮＩＣＯＬＥＴ２０ＤＸＢ傅里叶变换红外光谱仪的差减光谱（差谱）软件对复杂混合物的光谱成功地进行了二次光谱图的差减，得到了很好的单一组分的红外光谱图，从而鉴定了塑料焊接剂主成分的结构。     

三维荧光光谱差谱法测定柴油中的溶剂油

文章通过三维荧光光谱差谱技术研究了柴油中混有溶剂油的性质.这种技术可以快速分析出柴油中是否含有120#溶剂油,并对差谱后的三维谱进行体积分发现,总的体积与柴油中含有120#溶剂油的百分含量有一定的关系.这对于分析市场上柴油的真伪、维护市场稳定具有重要的意义.     

用差谱法研究环氧树脂中基团的相对稳定性

环氧树脂是一类广泛应用的万能胶,其分子中各种官能团的相对热稳定性是实际应用的重要参数。本文用付里叶变换红外光谱为测试手段研究了室温与降解条件(300℃、1小时)下的己固化环氧618树脂,用差谱法得到了固化的环氧618中各官能团的热稳定性次序为:甲基>次甲基>对位取代苯环>醚健>同碳二甲基。     

组织模型偏振后向散射差分光谱的测量

建立了一套用于测量生物组织模型偏振后向散射差分光谱的实验系统。在系统中,线偏振光入射到样品表面,检偏器和光谱仪配合记录后向散射光中的平行和垂直分量,随后计算出差分光谱。采用了平均直径分别为5.0μm、9.0μm的两种聚乙烯小球悬浮液进行实验,结果与蒙特卡罗模拟进行对照,验证了实验系统的正确性。初步研究了粒子尺寸分布变化对差分光谱的影响,结果表明,偏振散射差分光谱能敏感地反映粒子尺寸分布的变化,在大小粒子的混合液中,大粒子浓度一定程度的增加,光谱仍保留小粒子的振荡趋势,但差分光强减小。该方法对于早期癌症检测具有潜在应用意义。     

差谱技术用于实时遥测化学蒸气微弱光谱

ＲＦＸ－４０干涉型被动式傅立叶变换红外光谱仪用于远距离遥感化学蒸气微弱红外光谱。本将着重讨论化学蒸气红外辐射的传输特性及差谱技术用于抑制大气辐射对微弱目标的影响，增强化学蒸气光谱的特征。     

The infrared and laser Raman spectra of K2Zn(SO4)2 · 6H2O

The Raman spectra of the single crystal of K₂Zn(SO₄)₂·6H₂O belonging toC _2h ⁵ space group in the 40–1200 cm⁻¹ region in different scattering geometries and their spectra ofthe microcrystalline salt in the 1500-50 cm⁻¹ region have been reported. The dynamics of the crystal has been described in terms of 186 phonon modes under the unit cell approximation. The weak bands in the region 400–900 cm⁻¹ have been assigned to the libratory modes of H₂O molecules in contradiction to the assignments reported by Ananthanarayanan. The ambiguities existing in the literature about the assignments ofν ₂ ^c andν ₅ ^c modes of [Zn(H₂O)₆]²⁺ have also been removed. The translatory and libratory modes of different units of the crystal have been identified and assignments are made using farir and Raman data on various isomorphous tutton salts. It has been inferred that both SO ₄ ²⁻ tetrahedron and [Zn(H₂O)₆]²⁺ octahedron undergo linear as well as angular distortions from their free state symmetries in the crystal.     

Ab Initio Study on Structures and Vibrational Spectra of M+(H2O)Ar2 (M = Cu,Au)

Previous investigations have shown that it is difficult to acquire the infrared (IR) spectra of M⁺(H₂O) (M?=?Cu, Au) using a single IR photon by attaching an Ar atom to M⁺(H₂O). To explore whether the IR spectra can be obtained using the two Ar atoms tagging method, the geometrical structures, IR spectra and interaction energies are investigated in detail by ab initio electronic structure calculations for M⁺(H₂O)Ar₂ (M?=?Cu, Au) complexes. Two conceivable isomeric structures are found, which result from different binding sites for two Ar atoms. CCSD(T) calculations predict that two Ar atoms are most likely to attach to Cu⁺ for the Cu⁺(H₂O)Ar₂ complex, while the Au⁺(H₂O)Ar₂ complex prefers the isomer in which one Ar atom attaches to an H atom of the H₂O molecule and the other one is bound to Au⁺. Moreover, the calculated binding energies of the second Ar atom are smaller than the IR photon energy, and so it is possible to obtain the IR spectra for both Cu and Au species. The changes in the spectra caused by the attachment of Ar atoms to M⁺(H₂O) are discussed.     

Theoretical study of the electronic structure of a tetragonal chromium(III) complex

The low-temperature single-crystal polarized absorption and the luminescence spectra of Cs₂[CrCl₂(H₂O)₄]Cl₃ are theoretically analyzed in order to determine the electronic structure of the trans-[CrCl₂(H₂O)₄]⁺ complex. This study, based on the Racah theory, leads to a good agreement between the theoretical and experimental energy levels. The electronic-exited state ⁴T_2g(O_h) is split into ⁴E_g and ⁴B_2g components due to the lowering of the symmetry from O_h to D_4h. The polarized absorption spectrum and the theoretical energies show that the ⁴E_g(D_4h) state is lower in energy than the ⁴B_2g(D_4h) state. The resolved vibronic structure in the luminescence spectrum reveals a progression in a non-totally symmetric b_1g mode, a manifestation of a Jahn-Teller effect in the emitting state ⁴T_2g(O_h). Both Jahn-Teller and spin-orbit coupling in the orbitally degenerated ⁴E_g(D_4h) state are necessary to account for the spectroscopic observations.     

The Infrared and Raman Spectra of β-and α-Tricalcium Phosphate (Ca3(Po4)2)

Factor group analysis was applied to interpret the vibrational spectra of β-and α-tricalcium phosphate (Ca₃(PO₄)₂). The analysis predicts the number of bands formed due to the splitting of the fundamental vibrational modes of the PO₄ ^3-ion. The number of the infrared and Raman bands predicted by this analysis for the two phases are drastically different and can be ascribed to the difference in atomic arrangements in the two phases resulting in greater shielding of the PO₄ ^3-ions in the β-phase than in the α-phase. Discrepancies in the number of predicted and experimentally-observed bands can be attributed to the weak intensities of some vibrational modes or the convolution of vibrations and limited spectral resolution.     

Fluctuation kinetics of the hopping fluorescence quenching in disordered solid solutions: A theoretical model and experimental evidence

Fluctuation kinetics of the hopping fluorescence quenching in disordered solid solutions is investigated for the first time. Measurements were made in the chelated complexes of rare-earth ions [Y_1−xTb_x(pyca)₃(H₂O)₂]nH₂O used as chromophore. The Tb³⁺ ions and the OH^--ions of unbounded water molecules appear as fluorescent donors and randomly distributed acceptors, respectively, with the dipole-dipole interaction between them. The measured fluctuation kinetics is the kinetics of the Förster type but with larger decay amplitude. It begins almost immediately after the initial static stage of quenching, and lasts for the entire interval of measurements leaving no room at all for the well-known exponential kinetics with constant rate. Proposed theoretical explanation of the phenomenon is based on the solution of the closed many-particle integral equation for the observable kinetics of hopping fluorescence quenching. The methods for determination of the energy transfer microparameters by the measured fluorescence quenching kinetics are discussed.     

The oxidation of fullerene [C70] with various oxidants by ultrasonication

The reaction of C₇₀ by ultrasonication with various oxidants such as 3-chloroperoxy benzoic acid (Fluka 99%), 4-methyl morpholine N-oxide (Aldrich 97%), chromium (VI) oxide (Aldrich 99.9%), and oxone^® monopersulfate compound, at room temperature causes the oxidation of fullerene [C₇₀(O)_n] (n=1–2 or n=1). The FAB-MS, UV–visible, FT-IR spectra, and HPLC analysis confirmed that products of fullerene oxidation are [C₇₀(O)_n] (n=1–2 or n=1).     

The Infrared and Raman Spectra of Tetracalcium Phosphate (Ca4P2O9)

The infrared and Raman spectra of tetracalcium phosphate (Ca₄P₂O₉) were measured and interpreted on the basis of factor group analysis. Factor group splitting can be noted for the various internal vibrational modes of the PO₄ ^3- ion. However, a fewer number of factor group-split bands can be seen than predicted because of either the weak intensities of these bands or the convolution of such bands for the various internal modes of vibration.     

The Infrared Spectra of the First Transition Series Metal(II) Bis(Aquo) Complexes Of 8-Hydroxyquinoline

Abstract

The infrared spectra (700–100 cm^?1) of the complexes [M(ox)₂(H₂O)₂] (ox = 8-hydroxyquinolinate anion, M = Mn, Fe, Co, Ni, Cu, Zn) are discussed. For the purposes of assignment of the metal ligand modes, deuterated 8-hydroxyquinoline-d ₇ was prepared by the Skraup synthesis and the spectra of the deuterated complexes were compared with those of the unlabelled species. Furthermore, [⁶⁴Zn(ox)₂(H₂O)₂] and [⁶⁸Zn(ox)₂(H₂O)₂] were prepared by reaction of ⁶⁴ZnSO₄ and ⁶⁸ZnSO₄ with 8-hydroxyquinoline and the effects of metal isotope labelling on the spectra were examined and compared with earlier isotopic data on the nickel and zinc complexes.     

Luminescence characteristics of Na21(SO4)7F6Cl:Cu+ phosphor

Copper-doped Na₂₁(SO₄)₇F₆Cl phosphor was synthesized via the conventional wet chemical method. The synthesis was carried using CuCl₂ and Cu (NO₃)₂·3H₂O as dopants in two different steps successively. The formation and phase purity of the compound were revealed by the X-ray diffraction pattern. Functional groups of the prepared phosphor were observed in the FT–IR spectrum. The emission along with excitation spectra were followed to explore the luminescence attributes. Photoluminescence (PL) emission spectrum of the material synthesized using CuCl₂ as the dopant was observed at 358?nm due to 3d^l0?3d⁹4s transitions when excited around 247?nm for various copper concentrations. Efficient blue emissions were obtained at peaks 423 and 469?nm for materials synthesized using Cu (NO₃)₂·3H₂O as the dopant, when monitored at 357?nm excitation. The Commission Internationale de I’Eclairage chromaticity coordinates for different copper concentrations were calculated for the emission around 423?nm. TL glow curves of Na₂₁(SO₄)₇F₆Cl:Cu phosphor for different dopant concentrations, irradiated with 100?Gy gamma dose, were studied and hence the trap parameters, namely order of kinetics (b), activation energy (E) and frequency factor (s) associated with the most intensive glow peak of Na₂₁(SO₄)₇F₆Cl:Cu phosphor were determined by using Chen’s Peak shape method. The results indicate that Na₂₁(SO₄)₇F₆Cl:Cu⁺ is a potential novel blue-emitting lamp phosphor and may be quite suitable for use in dosimetry of ionizing radiations.