The pentacene films on the glass/ITO surface: structure and optical properties

Abstract

The structure, morphology and optical transmittance spectra of pentacene films on the (glass/ITO) surface were studied. The films were grown by two methods - the thermal vacuum deposition (TVD) and pulsed laser deposition (PLD). The electron diffraction pattern from thermally deposited pentacene films confirms their polycrystalline structure while the diffraction pattern of PLD-coated layers has a diffusion character. The results obtained showed that layers deposited by the TVD method has an optical spectrum that is characteristic for the pentacene film in contrary to the layers deposited by the PLD method. It is found a sensitivity of the optical transmittance of pentacene films to the ammonia action, which may be used for development the optical gas sensor.     

Molecular structure,vibrational spectroscopic and chemical reactivity of nematogenic p-n-alkylbenzoic acids: A comparative computational analysis

Molecular structure and vibrational spectroscopic studies of higher homologous series nematogenic p-n-alkylbenzoic acids (nBAC) that have 6 (6BAC) and 7 (7BAC) carbon atoms in the alkyl chain have been investigated using the Density Functional Becke3-Lee-Yang-Parr (B3LYP) level with the basis set 6-31++G (d.p) and Hartree Fock (HF) with the same basis set. The observed vibrational spectra has been resolved and assigned in detail for comparision with both the molecules. These results indicate that DFT and HF values are slightly different at both the levels. A comparision of chemical reactivity such as HOMO (E_H), LUMO (E_L) energies, energy gap (E_g), ionization energy (I), electron affinity (A), electro negativity (χ), chemical hardness (η), electronic chemical potential (μ), electrophilicity index (ω), and softness (S) has been made. It has been observed that the decrement has occurred in the energy band gap value of isolated molecule with increment in alkyl chain length. This provides valuable information regarding enhancing the stability of liquid crystal materials by maintaining the conductivity.     

Functional Organic Semiconductors Based on Bay‐Annulated Indigo (BAI)

The advancement of organic electronics has been continually pushed by the need for stable and high performance acceptor materials. By utilizing inexpensive and stable indigo dye as a starting material, Bay‐Annulated Indigo (BAI) provides a new motif for the development of semiconducting materials. Modular and straightforward synthesis makes BAI an outstanding platform for molecular design, while excellent stability, strong absorption, and high ambipolar mobility render BAI‐based materials excellent candidates for organic electronics. BAI‐based polymers and small molecules have taken advantage of these properties to show promising results in a variety of applications.     

Highly sensitive perylene tetra-(alkoxycarbonyl) based colorimetric and ratiometric probes for fluorine detection

Fluoride anion (F^?) affects environmental, biological, and chemical processes significantly. Therefore, its detection has received increasing attention, and sensitive, effective, and convenient probes for F^? detection need to be developed urgently. In this work, two perylene tetra-(alkoxycarbonyl) (PTAC) based colorimetric and ratiometric probes, P1 and P2, were developed for the detection of F^?. The interactions between F^? and these two probes were investigated by absorption, electrochemistry, ¹H NMR, and density functional methods. Both the two probes were complexed with F^? with a ratio of 1:1. The detection limits of P1 and P2 were 0.22 μM and 0.87 μM, respectively. It was worth noting that the absorption peak of P1 showed a 190 nm red shift when sensing F^?, and P1 is the largest red shift value reported in F^? probes based on PTAC derivatives. This phenomenon was resulted from the unique configuration and deprotonation of P1 that can promote the intramolecular charge transfer (ICT). This strategy provides an example for the development of other ion probes based on D-A type ICT mechanism.     

常压下玉米秸秆液化工艺的优化及其生物油分析

随着化石能源的日益短缺，可再生木质生物质资源的利用越来越受到重视，常压液化技术是生物质资源高效利用的主要方式之一。利用单因素方法，探讨液化温度、复配液化剂二甘醇（DEG）与1,2-丙二醇（PG）的混合比、液固比、催化剂磷酸的用量、反应时间等因素对玉米秸秆液化得率的影响，以便优化其液化工艺；然后采用热重分析仪（TGA）、气相色谱-质谱技术（GC-MS）和核磁共振（NMR）技术对此优化条件下所得生物油的挥发降解特性和主要组成成分进行了检测探讨。分析表明，玉米秸秆液化时优化工艺参数为：液化温度170 ℃，液化剂DEG与PG混合比1∶2，液固比5∶1，H₃PO₄用量10%，反应时间45 min；此时玉米秸秆液化得率高至99.50%。TGA结果表明，此条件下所得生物油含有80%以上碳数小于25的化合物，热解后最终残炭量约为15%。GC-MS表明，可以检测出此生物油中含有的39种有机物，其中，醇类有机物的含量最多，酚类有机物的含量次之，它们相对含量依次是70.70%和25.63%，其还含有一定量的有机酸（2.80%）、醚类（0.64%）、酯类（0.10%）和酮类（0.13%）等有机物；其组分十分复杂，高含氧量，稳定性较差。1H-和13C-NMR分析表明，不同化学位移δ与生物油中不同类型的质子和碳原子相对应，明确生物油中不同类型H和C的分布，有利于对其分子结构进行深入探讨。这些研究为非木材生物质高效液化条件的选择及液化产物制备化学品和生物燃油给予理论基础与应用支持，促进了生物质资源的有效转化利用及其生物质基产品的开发。     

Lanthanum trilactate: Vibrational spectroscopic study − infrared/Raman spectroscopy

In this study lanthanum trilactate was prepared by neutralization reaction of lactic acid and lanthanum oxide, purified and identified by X-ray powder diffraction. Infrared spectra (Mid-IR region 4000–650 cm⁻¹) and Raman spectra (Stokes region 4000–100 cm⁻¹) of the high quality crystalline samples have been recorded and presented for the first time. For comparison DFT calculations were performed using Gaussian 09 D.01 and agreement between predicted and measured spectral data has been achieved. Acquired information can be utilized for substance identification for example in various industrial applications or in biological systems.     

如何解释红外谱图

红外光谱(IR)主要提供分子的官能团和化学键的丰富的结构信息。通常一个化学键会出现多个不同位置的吸收峰,而图中每个峰又可能是不同化学键的加合峰。因此在红外光谱分析中,并不要求也不可能准确地归属出图中所有的峰,通常只要求能较确切地识别出其中几个特征峰已足矣。     

氨基酸官能团的太赫兹振动模式研究

对比于氨基酸的红外分析法,太赫兹波的电子能量更低,可实现无损检测。氨基酸分子内原子振动、分子间氢键的作用、以及晶体中晶格的低频振动均处于太赫兹波段,使其在太赫兹波段具有吸收峰,且不同的氨基酸分子太赫兹吸收峰不同,故可用氨基酸在太赫兹波段的这种“指纹特性”实现氨基酸类物质的定性分析。量子化学分析方法可以应用量子力学的基本原理和方法,研究稳定和不稳定分子的结构、性能及其之间的关系,还可以针对分子与分子间的相互作用、相互碰撞及相互反应等问题进行研究。通过量子化学计算方法计算氨基酸分子的太赫兹吸收谱,可以为氨基酸分子的太赫兹吸收峰匹配分子振动模式,对氨基酸定性分析有一定参考性与指向性,并为实验获取的样品太赫兹时域光谱提供理论支撑,在实验获得太赫兹吸收谱的基础上进行量子化学计算,还能为实验结果进行验证。首先利用太赫兹时域光谱技术获取了谷氨酰胺、苏氨酸、组氨酸的太赫兹吸收谱,分别构建这三种氨基酸样品在实物中以两性离子形式存在的单分子构型,利用量子化学计算方法在完成结构优化后进行太赫兹吸收谱模拟计算。计算结果表明三种氨基酸单分子的太赫兹吸收谱计算结果与实验获取的太赫兹吸收谱差异较大,但在高频段吸收峰峰位基本吻合。通过GaussView分别查看了这三种氨基酸分子在太赫兹段内的吸收峰对应频率处的振转情况,发现在高频段内三种氨基酸分子官能团均只发生转动而未见振动,并且转动模式基本一致。通过对氨基酸官能团的太赫兹吸收谱进行量子化学计算,将官能团在高频段内吸收峰对应频率处的振转模式与三种氨基酸分子在该段内吸收峰对应频率处的振转模式做了对比。研究表明,在氨基酸单分子构型下由量子化学方法计算所得的太赫兹吸收谱中,高频段内计算得出的模拟吸收峰与实验获取的太赫兹吸收峰基本吻合;振转模式分析发现,谷氨酰胺、苏氨酸、组氨酸在太赫兹高频段内的氨基酸官能团振转模式相同,三种氨基酸分子在高频段内的吸收峰主要来源于氨基酸官能团。因此,结合量子化学计算与太赫兹吸收谱可以实现氨基酸类物质的定性分析。     

工业SO2及碳黑颗粒紫外成像遥感监测技术

为了准确有效监测工业烟囱排放,基于SO2及碳黑颗粒物的光学特性,设计并研制出一套双通道紫外成像遥感监测系统.该成像系统的两个光谱通道的中心波长分别定于310 nm和330 nm,利用两个通道的光学厚度之差反演SO2浓度图像,颗粒物浓度图像由330 nm通道获取,根据浓度图像结合光流法获取烟羽运动速度,进而计算得出SO2和碳黑颗粒物的排放速率.结果表明,该工业烟囱的SO2及碳黑颗粒物排放速率分别为72.48±3.16 kg/h和6.33±1.18 kg/h.实验采用紫外相机同时对工业烟囱排放的SO2及碳黑颗粒物进行监测,实验表明双通道紫外成像遥感监测兼具高时间分辨率与高空间分辨率,测量结果准确直观,在工业废气污染、船舶尾气污染以及火山喷发污染排放遥感监测中具有非常明显的技术优势及巨大的应用前景.