Layer-by-Layer Assembly of Monolayer Films Precisely Controlled by LB Technology to Realize Low-Energy Consumption and High-Stability Ternary Data-Storage Devices

Organic semiconductor devices with low energy consumption and excellent stability are highly desirable. Controlling the intermolecular alignment orientation by designing the molecular structure or optimization of the film preparation process is an alternative way to achieve this goal. In this paper, a new idea was proposed to realize the formation of an aligned monomolecular layer and multimolecular layer thin films on the electrode substrate by controlling the surface pressure of molecular layer on the liquid surface by LB technology. An amphiphilic π-conjugated D−A molecule was synthesized, and the influence of spin coating and LB technology on intermolecular ordered stacking in the film and the electrical memory performance were investigated. The results demonstrated that the film fabricated by LB technology has some advantages compared with that fabricated by spin-coating method, such as higher crystallinity, lower surface roughness and better-organized monomolecular and multimolecular layer, which significantly promoted the performance of the electrical memory device with lower power consumption and longer stability.     

Plasma Modified V2O5/PEDOT Hybrid Based Flexible Electrochromic Devices

Vanadium oxide/poly (3,4‐ ethylenedioxythiophene)(V₂O₅‐PEDOT) hybrid materials were prepared in a rotating quartz plasma reactor via capacitively coupled radio frequency (RF 13.56 MHz) plasma. Thin films of V₂O₅‐PEDOT hybrid and V₂O₅ were obtained by electron beam evaporation technique onto flexible PET substrate for electrochromic devices (ECDs) applications. As a counter electrode, both RF magnetron sputtered MoO₃ onto ITO coated PET and only ITO coated PET electrodes were used. Characterizations of the films were carried out via using scanning electron microscopy‐energy dispersive X‐ray spectroscopy (SEM‐EDX) and X‐ray diffraction (XRD). Hybrid ECDs results showed that synergistic effect depending on improved stability between V₂O₅ and PEDOT. As a result, we developed all solid complementary electrochromic devices including V₂O₅, V₂O₅‐PEDOT and MoO₃ films. The electrochromic device characteristics such as electrochromic contrast, coloration efficiency, switching time were calculated from optical and electrochemical measurements. The highest coloration efficiency and optical contrast were obtained as 53 cm²/C and 17 % for V₂O₅‐PEDOT/MoO₃‐based ECD.     

Modeling dewetting of ultra-thin solid films

We review some models for the dynamics of dewetting of ultra-thin solid films. We discuss the similarities and the differences between faceted and non-faceted systems. The faceting of the dewetting rim leads to corrections in the velocity of dewetting fronts both in flat and axisymmetric geometries. The faceting of the edge of the dewetting rim leads to a strong anisotropy of the dewetting instability. Faceting also induces novel dewetting regimes such as layer-by-layer dewetting, and monolayer dewetting.     

中心对称双酞菁铥LB膜二次谐波产生特性

利用二次谐波产生(SHG)方法研究了中心对称分子稀土夹心双酞菁铥(TmPc₂) Langmuir-Blodgett (LB)膜二阶非线性光学特性, 测量了二次谐波强度随入射基频光入射角的关系, 并对其二阶非线性产生机制进行了讨论. 实验结果表明, TmPc₂分子LB膜具有较好的二次谐波信号, 二次谐波信号强度的最大值在基频光入射角为45°的地方, 其二阶非线性极化率χ⁽²⁾和分子超极化率β分别为1.152×10^-8和1.905×10^-30 esu. 通过测量样品二次谐波信号的偏振特性, 并与理论分析相比较, 得出其二阶非线性起源于电四极子作用机制.     

Development of sheared and ultra-pure DNA thin films prepared by ultrasonication and purification

DNA solutions were prepared by ultrasonication and purification to compare the characteristics between DNA solutions different in size, purity, or both. Ultrasonication effectively minimized the size variation in native DNA, while purification enhanced the transparency of fabricated DNA thin film. Each DNA solution was used to fabricate water-soluble or organic-soluble thin film. According to the electrical measurement of DNA and CTMA-modified DNA thin films and the fluorescence measurement of PicoGreen-embedded DNA thin films, ultrasonication and purification affect the electrical characteristics and intercalating efficiency of DNA thin films. The electrical properties of the water-soluble thin film and the organic-dissolved thin film were predominantly affected by purification, but opposite tendencies were observed. The highest resistance was observed in water-soluble DNA thin film fabricated from ultra-pure DNA, whereas organic-soluble DNA thin film from ultra-pure DNA showed the lowest resistance. Ultrasonication showed a synergistic effect on PicoGreen-DNA insertion, whereas purification suppressed the fluorescence signal.     

支撑磷脂双层膜的研究进展

支撑磷脂双层膜(supported phospholipid bilayers,SPBs)是细胞膜研究中普及的模型,是固定生物活性物质的理想材料,不仅可以保持生物分子的活性,还能有效抑制其他生物分子的非特异性吸附,在跨膜蛋白、仿生膜、水处理、生物医学和生物传感器等研究领域具有广泛的应用前景。本文介绍了支撑磷脂双层膜的表征方法和制备方法,包括Langmuir Blodgett(LB)膜提拉法、囊泡融合法和LB膜提拉法与囊泡融合联合法;详细阐述了囊泡融合法制备SPBs的机理;综述了囊泡融合法制备SPBs的影响因素,包括囊泡浓度、缓冲溶液、温度、囊泡和基底表面电荷等因素;列举了支撑磷脂膜的应用,并展望了支撑磷脂双层膜的研究趋势。     

Comparison of the Adsorbed Mercury Screening Method with Cold-Vapor Atomic Absorption Spectrophotometry for Determination of Mercury in Soil

ABSTRACT

A field screening method for the determination of elemental mercury in environmental soil samples involves the thermal desorption of the mercury from the sample onto gold and then the thermal desorption from the gold to a gold-film mercury vapor analyzer. This field screening method contains a large number of conditions that could be optimized for the various types of soils encountered. In this study, the conditions were optimized for the determination of mercury in silty clay materials, and the results were comparable to the cold-vapor atomic absorption spectrophotometric method of determination. This paper discusses the benefits and disadvantages of employing the field screening method and provides the sequence of conditions that must be optimized to employ this method of determination on other soil types.     

Fourier Transform Infrared Spectroscopic Investigation on Langmuir-Blodgett Films of Octadecanoyl Ester of 1-(2-Carboxyethyl) Thymine: Molecular Orientation,Molecular Recognition to Complementary Base of Nucleic Acid and Order-Disorder Transition

Fourier transform infrared (FTIR) transmission, polarized transmission, reflection absorption (RA) and Attenuated total reflection (ATR) spectroscopy were employed to investigate the molecular orientation and molecular recognition to the complementary base at the air / water interface of a novel nucleolipid amphiphile, octadecanoyl ester of 1-(2-carboxyethyl) thymine. It has been found that the molecules are biaxially oriented and the hydrocarbon chain titled considerably from the substrate normal as well as the chromophoric part in the LB film Molecular recognition through complementary bases pairing takes place at the air / water interface between the thymine moiety in the head group of the amphiphile and adenosine in the subphase, the hydrogen involved in the host-guest interactions has been detected by using FTIR-ATR technique. FTIR transmission spectra measured at elevated temperatures revealed that the order-disorder transition of the LB film which contains the complementary base occurs at lower temperature. To our best knowledge, investigation of the order-disorder transitions in nucleolipid amphiphile LB films and comparative studies of the order-disorder transitions between nucleolipid amphiphile LB film that contains and does not contain the complementary bases have been virtually nonexistent, so far.     

磁控溅射技术制备TiO2薄膜的研究进展

介绍了磁控溅射法镀膜的基本原理,综述了近年来关于溅射功率、工作压强、氩氧比例、沉积温度和退火等工艺参数以及掺杂对T iO2薄膜结构、形貌和光学性质影响的研究进展,并对磁控溅射技术制备T iO2薄膜的发展方向进行了展望。     

Thermal annealing effect on the crystallization and optical dispersion of sprayed V2O5 thin films

Polycrystalline vanadium pentoxide (V₂O₅) thin films have been deposited by spray pyrolysis technique on preheated glass substrate. The influence of thermal annealing on the crystallization of V₂O₅ has been investigated. X-ray diffraction analysis (XRD) revealed that the films deposited at T_sub=350 °C were orthorhombic structures with a preferential orientation along 〈0 0 1〉 direction. Moreover, the degree of crystallinity was improved by thermal annealing. Optical properties of these samples were studied by spectrophotometer in the wavelength range 300-2500 nm. Some of the important optical absorptions such as optical dispersion energies E_o and E_d, dielectric constant ε, ratio between number of charge carriers and effective mass N/m^*, wavelength of single oscillator λ₀, plasma frequency ω_p, single resonant frequency ω₀ and the average of oscillator strength S_o, have been evaluated. In the annealing process, the dielectric properties have weak dependencies of film thickness and annealing time. Furthermore, a value of carrier concentration was obtained of 3.02×10²⁵ m⁻³ for the as-deposited film and slight changes with annealing time.