Perylene nanotubes fabricated by the template method

Aligned organic nanotubes of perylene with uniform diameters, lengths and wall thicknesses were fabricated via a simple immersion technique using a porous alumina membrane as the template.     

The effect of crystallization on doping efficiency in a-Si:H films

The structure of A-Si:H films can be changed by substitutional doping of boron and phosphours dopants. Proper regulation of technological parameters, Ts and r. f. power, can result in a mode transformation from amorphous morphology into microcrystalline or polysilicon like one. The crystallization of amorphous silicon film leads to a further reduction in its room-temperature resistivity by about three order of magnitude and a reduction in its activation energy of electrical conductivity.     

IFT系统空间过渡的极值曲线场

本文研究了空间最佳N冲击过渡问题(时间任意),导出了发动机点火过程中伴随系统的积分,从而得到了产生空间极值曲线场的程序。     

Investigation on high mobility nanocrystalline Si with crystalline Si heterostructure

A heterostructure of n-type hydrogenated nanocrystalline silicon (nc-Si:H) film with p-type crystalline silicon, i.e., (n)nc-Si:H/(p)C-Si, was fabricated to investigate carrier characteristics and transport. After electrical experiments, carrier information, such as hole and electron as well as 2-dimension electronic gas in the studied system, was identified respectively. The forward current conduction was analyzed while the reverse current transport was distinguished as different mechanisms within the different range of negative applied voltage. The performed study also leads us to ascribe the main origin of short transient times on the produced structure to a tunneling mechanism.     

Field emission and electrical bistable properties of CuTCPQ nanostructures

The organic charge-transfer (CT) complex nanostructures of CuTCPQ (copper tetracyanopentacenequinodimethane) were first successfully fabricated by organic solid phase reaction. The morphologies of CuTCPQ nanosrods can be prepared by controlling the reaction temperature. The electron field-emission properties on these nanostructures were investigated. The current density and turn-on field are 3.5 mA cm(-2) and 2.70 V μm(-1) for the nanorods of CuTCPQ. The results demonstrate that the nanorods of CuTCPQ are potential candidates for field emission cathodes. Stable and reproducible current-controlled electrical switch has been observed in amorphous organic nanorods of CuTCPQ films. The current-voltage characteristics reveal an abrupt decrease in impedance form 1.2 MΩ to less than 1.1kΩ. The maximum ON/OFF ratio of CuTCPQ nanorod arrays is up to 1100.     

Regioselectivity control of graphene functionalization by ripples

Ripples naturally occur in graphene sheets. First-principles calculations reveal that, by altering the pyramidalization angles of the carbon atoms, these ripples can be used to direct the chemical reactivity of graphene towards hydrogenation. A fraction of the carbon atoms of a rippled graphene, located around the crests and troughs, show significantly increased reactivity. The remaining carbon atoms have comparable reactivity to those in a flat graphene. To illustrate the increased reactivity, we show that hydrogenation becomes exothermic when the characteristic ratio between the amplitude and wavelength reaches ~0.55. This finding offers a practical chemical venue for regioselectivity control of graphene functionalization. While the rippling does not directly affect the band gap of the graphene, the rippling-induced hydrogenation does.     

Construction of heterostructure materials toward functionality

One- and zero-dimensional organic/inorganic heterostructure materials have been attracting considerable attention in materials science because of their outstanding optical and electrical properties and high tailorability in terms of composition, structure, and morphology. Strong interactions between the organic and inorganic units can lead to novel or improved physical or chemical performance relative to that of the individual components, thereby realizing synergistic ("1 + 1 > 2") performance. In this tutorial review, we discuss the synthetic methods available for preparing heterostructures incorporating diverse components; the functionality of the heterostructure materials; and their potential applications in the fields of electronics, optics, biology, and catalysis. The future development of such heterostructure materials will require deeper understanding of organic-inorganic or organic-organic interfaces on the nanoscale, collective phenomena, and interparticle coupling.     

Synthesis of a [2]rotaxane incorporating a "magic sulfur ring" by the thiol-ene click reaction

The mild and highly efficient thiol-ene click reaction has been used to construct a rotaxane incorporating dibenzo-24-crown-8 (DB24C8) and a dibenzylammonium-derived thread in high yield under the irradiation of UV light. A rotaxane containing a disulfide linkage in the macrocycle was also synthesized by the thiol-ene click reaction. It has been demonstrated that the formation of the [2]rotaxane with the disulfide bond in the macrocycle occurs by a mechanism that is different to the threading-followed-by-stoppering process. The successful construction of a rotaxane directly from its constituent components, the macrocycle containing a disulfide linkage and the dibenzylammonium hexafluorophosphate salt, suggests that the space within the macrocycle incorporating the disulfide linkage is smaller than the phenyl unit and a plausible reaction mechanism has been proposed as follows: A small amount of the initiator forms two radicals upon the absorption of UV irradiation; the radicals act as a "key" to "unlock" the disulfide bond in the macrocycle. The resulting crown ether like moiety in the macrocycle is clipped around the ammonium ion center in the dumb-bell-shaped compound. The [2]rotaxane is generated upon recombination of the disulfide linkage.     

火焰原子吸收光谱分析多元干扰体系中干扰效应的计算消除方法研究──Ⅰ.多元混合干扰效应的数学表达及算法

研究了火焰原子吸收光谱分析中多元混合干扰效应的计算消除方法．提出用多项式作为定量描述主测元素与干扰元素之间关系的通用数学模型，并对计算机自动寻找适宜的数学模型作了探讨。运用和尝试了一种新的下降算法──搜索法。本文是对多元统计方法在原子光谱分析中的应用的探索。在对多组分体系进行分析时，利用其元素间相互干扰时所形成的体系总吸光度与各组分浓度间的函数关系，用增量法去形成所需的系数矩阵，从而实现了在单波长处进行多元统计分析。