2-三苯基锗基乙基苯基酮、4-三氯锗基-4-甲基-2-戊酮及其类似物Raman及IR光谱

我们合成有机锗化合物的重要中间体 4-三氯锗基 - 4-甲基 - 2 -戊酮 ( A)、3-三氯锗基 -3,5,5-三甲基环己酮 ( B)、2 -三氯锗基 - 2 -苯基乙基苯基酮 ( C)、2 -三苯基锗基乙基苯基酮 ( D) ,测量了他们的 Raman和 IR光谱并进行了讨论。在化合物 A- D的 Raman和 IR光谱 ,苯环中的 C- H伸缩振动 ,饱和 C- H伸缩振动 ,饱和 Ge- C伸缩振动等特征数据基本一致。C=O伸缩振动在 Raman和 IR光谱中位置基本一致 ,但在红外光谱中均为强吸收带 ,而在 Raman光谱中的峰强度差别则非常大 ,化合物 A、D的峰非常弱 ,而 C的峰则很强 ,化合物 A- C的 Ge- Cl振动均在 390 cm- 1附近出现强峰。     

受激Raman谱中的宏观极化干涉

研究了Rb⁸⁵原子蒸气D1线系统中的受激Raman增益与损耗现象. 实验中观察到 随着抽运光失谐量的增大, 受激Raman谱明显地呈现出一个从增益到损耗的陡峭转变. 从缀饰态模型出发, 我们提出这是对探测光有相反贡献的不同速度原子群之间极化干涉的结果. 关键词： 受激Raman谱 电磁感应透明 极化干涉     

铷蒸气Λ-型系统中的受激Raman谱与光泵效应

从理论和实验上研究了⁸⁵Rb 原子蒸气D1线系统中的受激Raman现象. 在Λ-型能级系统中, 抽运光对弱探测光的影响有两部分: 受激Raman激发和光泵效应. 在一定的抽运光强度和失谐量条件下, 受激Raman谱表现为增益谱或损耗谱; 以光泵效应导致的吸收谱为背景时, 便分别形成了窄线宽透明窗口或线宽差异很大的吸收双线. 理论模拟和实验结果基本符合. 基于这些研究, 从新的角度阐述了在Λ-型系统中的电磁感应透明和Autler-Townes分裂这两个重要现象与受激Raman谱之间的关系. 关键词： 受激Raman谱 光泵效应 电磁感应透明 吸收双线     

反式乙烯基联吡啶表面增强拉曼光谱的密度泛函理论研究

反式乙烯基联吡啶具有极好的拉曼散射信号,经常用做探针分子.利用密度泛函理论(DFT)理论,采用BP86,BPw91和B3LYP等方法,Ag原子使用赝式基组,H,C,N等原子使用6-31+ +G(d,p)基组,计算了反式乙烯基联吡啶与银配合物(t-BPE-Ag)的Raman光谱,并且利用势能分布(PED)计算结果对t-BPE分子Raman光谱和SERS谱进行了详细的归属,DFT理论得到结果说明根据DFT理论计算t-BPE-Ag配合物得到的Raman光谱与实验SERS谱基本一致,并且键连Ag原子越多,与实验值会更接近,t-BPE-Ag配合物HOMO与LUMO的能级差估计在449～912 nm范围内.     

K_3Ba_3C_(60)在不同温度下的Raman光谱研究

研究了K3Ba3C60 在不同温度下的Raman光谱 .发现Raman光谱随温度的变化发生有规律的变化 .随着温度的降低 ,所有模的线宽和强度的变化情况与纯的C60 的情况明显不同 .径向Ag(2 )模的频率在 2 0K到室温之间有一个反常大的向高频漂移 (9cm-1) ,这表明在C60 分子和掺杂离子之间存在着轨道杂化 .另外Raman光谱中Ag(1)模两个分量的相对强度随着温度的降低发生有规律的变化 .     

X光电子谱辅助Raman光谱表征N含量对非晶金刚石薄膜的结构影响

用过滤阴极真空电弧沉积系统制备掺N非晶金刚石(ta-C:N)薄膜,通过在阴极电弧区和沉积室同时通入N2气实现非晶金刚石薄膜的N原子掺杂,并通过控制N2气流速制备不同N原子含量的ta-C:N薄膜.用X射线光电子能谱(XPS)和Raman光谱分析N含量对ta-C:N薄膜微观结构的影响.XPS分析结果显示:当N2气流速从2 cm3·min-1增加到20 cm3·min-1时,薄膜中N原子含量从0.84 at.%增加到5.37 at.%,同时随薄膜中N原子含量的增加,XPSC(1s)芯能谱峰位呈现单调增加的趋势,XPSC(1s)芯能谱的半高峰宽也随着N含量的增加而逐渐变宽.在Raman光谱中,随N原子含量增加,G峰的位置从1 561.61 cm-1升高到1 578.81 cm-1. XPs C(1s)芯能谱和Raman光谱分析结果表明:随N含量的增加,XPSC(1s)芯能谱中sp2/sp3值和Raman光谱中,ID/IG值均呈上升的趋势,两种结果都说明了随N原子含量增加,薄膜中sP2含量也增加,薄膜结构表现出石墨化倾向.     

过渡金属化合物的NMR

金属原子和配位体原子均可用作过渡金属化合物的NMR研究,它们的谱特征与常规的NMR谱不同,文中以¹H和⁹⁵Mo为例进行了讨论.     

X射线光电子能谱辅助Raman光谱分析类金刚石碳膜的结构细节

分别采用具有和不具有弯曲弧磁过滤器的两种真空阴极弧离子镀方法,在不同工艺参量下制备了类金刚石碳膜.采用Raman光谱和X射线光电子能谱(XPS),分析了不同工艺参量下的类金刚石碳膜的键结构,通过对Raman光谱的D峰、G峰和C1s电子结合能峰位、强度的对比,详细讨论了沉积工艺参量对类金刚石碳膜结构的影响.研究发现,不同工艺下具有高强度D峰Raman光谱的类金刚石碳膜,其C1s电子结合能却分别位于284.15,285.50eV,表明高度石墨化和高度金刚石化两种状态类金刚石碳膜,都可以形成具有高强度D峰Raman光谱曲线 关键词： 类金刚石碳膜 Raman光谱 X射线光电子能谱     

丁基苯酞衍生物的红外与拉曼光谱研究

丁基苯酞是我国脑血管领域第一个拥有自主知识产权的一类新药,常温下为一种淡黄色或者无色粘稠油状液体,具有众多优点,但在临床使用中会出现转氨酶升高、肝功能异常和消化道反应等不良反应。将卤素原子引入到丁基苯酞的6位,获得了3个固态的丁基苯酞类似物,并对其进行了IR和Raman光谱测定。两种光谱提供了互为补充的信息,引入卤原子后,双取代苯环的特征峰消失,出现了三取代苯环的特征峰。在红外中比较弱甚至检测不到的3位C—H伸缩振动在Raman中非常明显,在Raman的低波数区间检测到了可被指认为—C—C—C—C—的变形振动。根据这两种光谱的研究结果确认了所合成化合物的结构。     

利用Raman光谱计算铌酸锂晶体中Li的含量

根据商群对称性分析法对LiNbO3(简称LN)晶体的Raman光谱做了理论计算.测量了LN不同配置下的室温Raman光谱.利用155cm-1处的峰的半波宽计算了LN中Li的含量.结果证明我们所用LN样品是近化学计量比晶体.     

Covalent attachment of poly(ethylene glycol) on multi-walled carbon nanotubes

A new 'graft-onto' method to attach poly(ethylene glycol) (PEG) onto multi-walled carbon nanotubes (MWNTs) has been developed. The method is based on the coupling reaction of radicals formed at the chain end of PEG onto the surface of MWNTs. The polymeric radicals are generated by atom (halogen) transfer reaction between chloroacetyl-terminated PEG and transition metal catalysts. The method allows direct covalent attachment of PEG to pristine MWNTs without pretreatment that could alter their original structure. The resulting PEG-grafted MWNTs showed improved dispersion stability in isopropanol and methanol.     

Carbon clusters near the step of Rh surface: implication for the initial stage of graphene nucleation

To understand the initial nucleation of graphene by chemical vapor deposition along metal step, carbon clusters (N = 1 ～ 24) near Rh (4 3 3) stepwise surface were systemically explored by first-principles calculations. Carbon chains are always more stable than carbon rings on stepped metal surface. Starting from C₆, carbon chains prefer two-end passivation on the metal step. A structural transition of carbon clusters from one-dimensional sp chains to two-dimensional s p ² networks are found at C₁₀, which corresponds to the nucleation size at a wide range of chemical potentials. According to these theoretical results, we proposed that appropriately controlling the chemical potential may be helpful for observing the four stable carbon clusters along metal step and improving the quality of graphene.     

Effect of electric field on the electrical conductivity of defected carbon nanotube: Multifractal properties of the wavefunctions

A theoretical analysis of controllable metal–insulator transition is performed by carrying out a quantum chaos analysis for a single-walled carbon nanotube which is affected by topological Stone–Wales defect. Nanotubes have recently attracted attention as promising materials for flexible nanoelectronic devices. Individual topological Stone–Wales defects have been identified experimentally in carbon nanotubes (CNTs) and graphene. The findings reveal that defected CNT displays a gradual crossover from metal to insulator phase in a longitudinal electric field. By determining the threshold value of the electric field for metal–insulator transition, CNT may be used as a switch in electronic devices. Our results are obtained by calculating the singularity spectrum of a nearest-neighbor tight-binding model. Also, quantum chaos theory is used for obtaining a detailed understanding of a dynamic phase transition from delocalized states (chaotic) to localized states (Poisson). More interestingly, the appearance of negative differential resistance for pure CNT suggests potential applications in nanoelectronic devices.     

Role of point defects on conductivity, magnetism and optical properties in In2O3

In order to assess the effects of point defects including transition metal doping on its electronic structure, the self-consistent band structure of the transparent oxide In₂O₃ (in the Ia₃ structure) has been calculated with oxygen vacancies, oxygen and indium interstitial atoms and several transition metal dopants using density functional theory based first principles calculations. An oxygen vacancy alone does not act as a strong native donor but when combined with interstitial indium and (substitutional) transition metal doping, shallow donor levels close to the conduction band are formed. Spin polarized calculations show measurable magnetism in some of the transition metal doped systems while the dielectric functions indicate whether such systems remain transparent among other things.     

碳纳米管负载矾的第一性原理研究

本文基于密度泛函第一性原理研究了原始和带有缺陷的(Stone-Wales缺陷和单空位缺陷)碳纳米管负载金属V的稳定构型.对于V吸附在原始碳纳米管(CNT)上时,V在内表面的吸附比外表面的吸附有更强的相互作用力,且六元环内表面结构最稳定.当V与Stone-Wales缺陷碳纳米管相互作用时,V原子易吸附在管外七元环C-C键的外表面和内表面处,这说明缺陷位置的有效结合使之局域化加强.而以单空位缺陷碳纳米管为载体时V最易吸附在外缺陷处,相当于碳纳米管的一个C被金属V原子取代,形成了3个V-C_(sur)键,这进一步表明SV管外吸附比管内吸附更容易.我们从上述三种构型载体中发现,金属V吸附在缺陷碳纳米管时的稳定性要优于原始碳纳米管,且SV缺陷对金属V的固定效果最好.     

Polypropene nanocomposites by metallocene/MAO catalysts

In our experiments, monospheres (balls of silica, diameter 200–250 nm), carbon fibers (diameter 200 nm, length 0.5–3 mm) and carbon nanotubes (diameter 15–25 nm, length 50 μm) were used as fillers. Before polymerization, the fillers were separated by ultrasound and then treated by methylaluminoxane (MAO). The MAO reacts partially with the OH-groups of the silica and the formation of methane. Catalytically active centers are formed after adding the zirconocenes or other transition metal complexes. The thickness of the polyolefins can be controlled by the pressure of ethene or propene and by the polymerization time. By this method, highly filled nanocomposite polypropenes can be obtained with a silica content of up to 60 wt%. Such combined materials are stiff and hard. Every particle is surrounded by a thin film of polyolefin with a thickness of 30 to 100 nm. Carbon fibers and carbon nanotubes can be covered also within isotactic or syndiotactic polypropene. Because of the hydrophobic character of the carbon surface, the polymer is drawing on the fiber. This leads to a reinforced combined polymer with special properties.     

PREPARATION OF NANOWIRES AND MICROARRAYS

We report on the synthesis of one-dimensional (1D) solid nanostructures and ordered microarrays consisting of nanowires and carbon nanotubes. For 1D nanostructures, several synthesis methods, such as, carbothermal reduction of silica xerogels containing carbon nanoparticles, chemical vapor deposition on mesoporous active carbon with transition metal catalyst nanoparticles inside the pores, and simple physical evaporation with the help of transition metal nanoparticles as catalysts, have been used. For microarrays, anodic alumina membranes (AAMs) with highly ordered honeycomb structure were used as templates, chemical vapor reaction inside the nanochannels, Sol-gel technique, and selective electrodeposition in the channels, have been used to prepare microarrays embedded in AAMs.     

过渡金属Pd掺杂AsP结构及其吸附甲醛和一氧化碳的性能研究

基于第一性原理方法,研究了单层本征磷砷AsP和过渡金属钯（Pd）掺杂磷砷AsP的结构,并对比研究了本征和掺杂后的AsP吸附甲醛（HCHO）和一氧化碳（CO）气体分子的稳定性、能带结构、态密度以及电荷差分密度。研究结果表明：经Pd掺杂后AsP由半导体转变为导体;本征AsP吸附一氧化碳最稳定的位置为P-As键顶上,吸附甲醛最稳定的位置为P原子顶上;本征吸附时气体分子与基底之间的距离在3 Å左右,气体分子与基底之间未形成化学键。过渡金属Pd原子掺杂AsP后形成两种结构,分别为Pd原子替换超胞结构中的As原子或P原子。两种掺杂结构分别吸附一氧化碳或甲醛气体分子时,除了Pd原子替换AsP中的As原子形成的结构吸附甲醛的吸附能未明显增加外,其余掺杂结构吸附一氧化碳或甲醛的吸附能和电荷转移较本征吸附时均显著增强,吸附CO分子时,C原子与Pd原子之间形成了化学键。特别是,Pd原子替换AsP中的P原子形成的结构对一氧化碳和甲醛气体分子的吸附性能明显强于Pd原子替换AsP中的As原子所形成的结构。     

Fabrication and characteristics of ta-C biomaterial coatings on Ti–6Al–4V using metal plasma immersion ion implantation and deposition

We have formed amorphous diamond (ta-C) coatings on Ti–6Al–4V substrates using a metal plasma immersion ion implantation and deposition (MEPIIID) technique, and characterized the mechanical properties and biological compatibility of the coating material. The hemocompatibility of the coating compared favorably with that of low temperature isotropic (LTI) carbon, with kinetic clotting time and hemolysis rate approximately the same as for LTI carbon, and platelet consumption about twice that of the latter. The mechanical properties were good, with a microhardness greater than that of the uncoated metal substrates, and high adhesion of >0.75 GPa (interface shear stress) as estimated from a thermal quench method. Glancing-angle X-ray diffraction measurements indicated the presence of a TiC transition layer, suggesting the formation of a Ti/TiC/ta-C multilayer structure, leading in turn to good film–substrate adhesion. We conclude that this kind of amorphous diamond coating could provide benefit as a biocompatible hard coating for Ti–6Al–4V substrate material.     

Magnetic Nanocomposites Formed by FeNi3 Nanoparticles Embedded in Graphene. Application as Supercapacitors

A general family of magnetic nanocomposites formed by FeNi₃ ferromagnetic nanoparticles (NPs) embedded in a graphitized carbon matrix is reported. The soft chemical approach used relies on the catalytic effect of the NPs resulting from the thermal decomposition of the layered double hydroxide precursor, which acts as a multilayered nanoreactor enabling the formation of a range of carbon nanoforms (CNFs). This is followed by acid treatment of the as‐prepared nanocomposites to isolate the different CNFs formed. These range from carbon nano‐onions to graphene depending on the temperature of the thermal decomposition. This synthetic process paves the way for the rational design of metal–carbon nanocomposites with controllable composition as precursors of nanocarbons or even graphene. The coexistence of metal NPs and nanostructured carbon is a major source of applications. As a proof of concept, the electrochemical performance of these metal–carbon hybrid supercapacitors is studied under high discharging current densities and they exhibit high values of specific capacitance and excellent rate capabilities.