变温FT-Raman光谱研究一种手性液晶的相变

利用ＦＴ－Ｒａｍａｎ光谱研究了一种含手性基团的液晶分子的相变过程，并对不同温度点及相转变点的拉曼光谱进行了简单的指认，对在不同晶体中分子的结构与取向进行了简单的分析。     

向列型液晶的硬棒理论与分子取向短程关联

在向列型液晶的硬棒理论中引入分子取向短程关联。理论的出发点是Ｓｉｎ－ＤｏｏＬｅｅ的自由能表示，这一表示基于Ｃａｒｎａｈａｎ－Ｓｔａｒｌｉｎｇ状态方程。用包括了分子短程关联的取向熵代替原来平均场形式的取向熵项，得到新的自由能表示。通过自由能对分子取向分布求变分确定平衡态分布。对液晶ＰＡＡ进行了数值计算。给出了相变点序参数、熵变、相变点致密度和相对密度变化的计算值。考虑短程关联后的理论值较通常硬棒理论有显著改进。因此，在某种程度上克服了硬棒理论的困难。     

静电场与非共振脉冲激光电场共同作用下分子取向的机制

本分析了静电场与非共振的线偏振激光脉冲电场共同作用下分子取向的机制，发现如果激光脉冲足够宽，当激光光强确定后，脉冲的形状对分子取向起着决定性的作用。中进一步挖掘了这种现象背后分子取向的机制，得出了获得高效分子取向的必要条件，并建议将所得的结论应用于短脉冲下的‘postpulse orientation’。     

胆红素铬合物的表面增强拉曼光谱研究

本文通过对近红外激发傅里叶变换拉曼光谱（ＮＩＲ－ＦＴ－Ｒａｍａｎ）与表面增强拉曼散射（Ｓｕｒｆａｃｅ Ｅｎｈａｎｃｅｄ Ｒａｍａｎ Ｓｃａｔｔｅｒｉｎｇ,ＳＥＲＳ）技术的联用,没得胆红素及其络合物Ｎａ２ＢＲ,ＣａＢＲ与ＣｕＢＲ在银溶胶中的ＳＥＲＳ光谱。结果表明,这一类与胆结石密切相关的生物分子络合物具有不同的配位方式,且在银胶表面采取不同的吸附取向,并从配位化学角度初步解释了黑色结石的黑色成因。     

离焦系统下的单分子三维取向研究

提出了一种新思路来确定单分子的三维取向,在全内反射荧光显微成像的基础上,在显微镜的油镜上加一个水层,水和油的折射率不同造成光程差,产生离焦,利用全内反射产生隐失波激发了单分子的纵向分量,并在探测器前增加了一个分光镜,把光路分成偏振方向相互垂直的两束光,使得探测器上的光场分布包含单分子三维取向的信息。推导了隐失场激发的偶极矩光场在探测器上的光强分布表达式,通过分析偏振方向相互垂直的两束光在探测器上的不同的强度分布,来判断单分子偶极矩的三维取向。     

多孔硅银淀积表面RhB染料分子的表面增强Raman散射

我们采用多孔硅和多孔硅银淀积表面作为衬底研究了ＲｈＢ染料分子的表面增强Ｒａ ｍａｎ散射。在多孔硅表面,ＲｈＢ染料分子的Ｒａｍａｎ散射有大约１０倍的表面增强效果;而在多孔硅的银淀积表面,表现出超过１０４表面增强。通过多孔硅表面银颗粒对ＲｈＢ染料分子荧光的抑制和对Ｒａｍａｎ散射的表面增强,我们获得了谱峰清晰的ＲｈＢ染料分子Ｒａｍａｎ散射谱     

(002)取向AIN薄膜的Raman光谱

（００２）取向ＡＩＮ薄膜的Ｒａｍａｎ光谱赵永年王波何志罗微邹广田（吉林大学超硬材料国家重点实验室长春１３００２３）ＲａｍａｎＳｐｅｃｔｒａｏｆＡＩＮＦｉｌｍｓＯｒｉｅｎｔｅｄｉｎ（００２）ＺｈａｏＹｏｎｇｎｉａｎ，ＷａｎｇＢｏ，ＨｅＺｈｉ，ＬｕｏＷｅ...     

直流电弧等离子体射流CVD制备多种碳膜

本文报道了在同一直流电弧等离子体射流ＣＶＤ装置上，采用不同的沉积条件高速合成金刚石，类金刚石，高取向热解石墨以及无定形碳等四种碳膜。经Ｘ射线衍射（ＸＲＤ），拉曼散射谱（Ｒａｍａｎ），扫描电镜（ＳＥＭ）形貌分析以及显微硬度测试表明，该方法制得的金刚石膜和高取向热解石墨膜具有很高的纯度和良好的晶性，类金刚石具有独特的形貌和Ｒａｍａｎ散射特征以及可与金刚石膜比拟的硬度。     

静电场与非共振脉冲激光电场共同作用下分子取向的机制

本文分析了静电场与非共振的线偏振激光脉冲电场共同作用下分子取向的机制,发现如果激光脉冲足够宽,当激光光强确定后,脉冲的形状对分子取向起着决定性的作用.文中进一步挖掘了这种现象背后分子取向的机制,得出了获得高效分子取向的必要条件,并建议将所得的结论应用于短脉冲下的‘post-pulse orientation'.     

双甘氨肽与高定向热解石墨的散射动力学研究

本文通过反应力场来研究中性双甘氨肽与高取向热解石墨的碰撞动力学过程，分别模拟初始入射角度为0o、20o、45o和70o以及入射能量为481.5 kJ/mol和表面温度为677 K的情况，并且确定和分析了散射产物的角度分布、平动能分布、内能分布和表面滞留时间分布. 双甘氨肽是一种多原子分子，具有较多的低频振动模式和较强的表面吸附相互作用，这些使得碰撞过程的表面滞留时间较长和容易造成能量损失，尤其是表面法线方向. 由于碰撞分子的动量沿表面法线方向上明显地发生损失，而沿表面平行方向上的动量则会大部分保留，因此，其散射角通常会呈现出超镜面反射分布，并且末态的平动能要远小于所谓硬立方模型的预测值. 本文加深了多肽分子与高取向热解石墨碰撞及其能量转移过程的认识和理解，有助于设计在稀薄大气中收集这类大分子的中性气体浓缩器.     

Introduction to Terahertz Raman spectroscopy

This work, intended for advanced undergraduate students, explains the basic concepts and an actual scientific use of Terahertz Raman spectroscopy, displaying some of the benefits of this versatile technique for structural analysis of molecules building up materials since this technique has been increasingly used for molecular characterization in chemistry. A good didactic example of the experimentally applied temperature dependence of molecular vibrations according to the Boltzmann distribution is the ratio of anti-Stokes to Stokes Raman peak intensity used to calculate the temperature of a nylon 6,6 sample. The comparison of the temperature of nylon 6,6 calculated from the experimentally determined anti-Stokes to Stokes peak intensity ratio in the Terahertz region with the temperature set with the help of a heating-freezing stage is discussed. The limitations of Terahertz Raman spectroscopy are also part of this fundamental discussion.     

Comparative Raman spectroscopic analysis of orientation in fibers and regenerated films of Bombyx mori silk fibroin

This study is focused on the Raman spectroscopic analysis of degummed silk fibroin (SF) fibers and regenerated Bombyx mori silk fibroin films: a correlation was found between some spectral features related to the methylene deformation modes and the molecular orientation of the samples. Polarized Raman spectra on SF fibers were used to obtain the orientation distribution function of carbonyl groups along the protein backbone. The variation of the intensity ratio of 1400/1450 cm⁻¹ for the peaks attributed to the wagging and bending deformation modes of CH₂ groups with respect to the angular orientation of the fiber was measured and quantitatively correlated with the orientation distribution function of the carbonyl groups. Unpolarized Raman spectra were measured for regenerated silk fibroin films and lyophilized solutions. The variation of the intensity ratio of 1415/1455 cm⁻¹, which is related to the deformation modes of CH₂ groups in SF regenerated materials, was qualitatively related to the microstructural orientation of the samples observed by scanning electron microscopy (SEM), and to the presence of Silk I phase as suggested by the analysis of samples obtained in different casting conditions and also by the measurements on mechanically deformed films. The results obtained showed the utility of the spectroscopic intensity ratio of 1400/1450 cm⁻¹ for the rapid assessment of molecular orientation in silk fibers, which could be useful for quality and process control of regenerated silk‐based textiles. Moreover, the qualitative dependence of the intensity ratio of 1415/1455 cm⁻¹ was found to be sensitive to both the microstructural orientation and Silk I content of regenerated silk fibroin films, suggesting a possible correlation of this Raman marker of the Silk I phase with the degree of molecular order brought about by this polymorph. Copyright © 2006 John Wiley & Sons, Ltd.     

分子的取向和激光强度对非时序双电离的影响

利用半经典再散射模型,分别研究分子的取向平行和垂直于电场方向时反冲离子的动量分布、两电子的动量相关和隧穿电子的电离能分布.计算结果表明,分子的取向和激光强度对非时序双电离过程有重要的影响.     

西佛碱型液晶化合物相变过程中分子排列方式变化的拉曼光谱研究

用变温拉曼光谱对相变过程的研究表明,液晶化合物的初始晶态与熔融后缓慢降温得到的晶态并不吻合,两个状态下分子尾链的构象及刚性核部分的构象不同导致分子的聚集状态不同。西佛碱型液晶化合物VO10相变过程中,在晶态到液晶态相转变过程中,烷氧基尾链链内构象发生突变,同时有序性降低,刚性核部分两个苯环之间的二面角在相变点时发生明显变化,二面角加大。     

Raman tensor analysis of hexagonal polyoxymethylene and its application to study the molecular arrangement in highly crystalline electrospun nanofibers

The orientation dependence in space of Raman‐active vibrations in the hexagonal structure of polyoxymethylene (POM) is discussed in terms of Raman tensor elements as intrinsic physical parameters of the lattice. The variation of polarized intensity for the A₁ and the E₁ vibrational modes with respect to the POM molecular orientation is systematically studied, from both theoretical and experimental viewpoints, according to the symmetry assignments of each vibrational mode. A set of working equations including the Raman selection rules associated with the A₁ and the E₁ modes and the orientation distribution function are explicitly formulated and validated by means of a least‐square fitting procedure on experimental data. In addition, an approach based on the introduction of orientation distribution functions is applied to quantitatively assess and compare on a statistical base the molecular orientation of two different types of electrospun POM nanofibers. Copyright © 2012 John Wiley & Sons, Ltd.     

SERS and Raman imaging as a new tool to monitor dyeing on textile fibres

Textile fibres containing Ag nanoparticles have been widely explored for a number of antimicrobial fabrics. Moreover, it is well‐known that textile dyeing is a critical stage in the manufacture thereof. This research shows that surface enhanced Raman scattering (SERS) and Raman imaging can be used with advantage in the monitoring of this process. Using Ag containing linen fibres stained with methylene blue (MB), it was possible to map the local distribution of the MB dye in the fibres by Raman imaging. MB was selected as the SERS molecular probe and as a model dye. Composites of linen fibres and Ag nanoparticles were prepared by distinct methods and used as SERS substrates in order to evaluate the effect of the preparative method on the Raman images. Our results demonstrate that by using Raman imaging associated to the presence of Ag nanoparticles, it is possible to distinguish the local distribution of the dye on the textile surface. This investigation allows to foreseeing the use of this technique in terms of quality control of Ag containing fabrics, which is a market in great expansion. Copyright © 2016 John Wiley & Sons, Ltd.     

Superresolution vibrational imaging by simultaneous detection of Raman and hyper-Raman scattering

We have developed a superresolution vibrational imaging method by simultaneous detection of Raman and hyper-Raman scattering. Raman and hyper-Raman images obtained with the same laser spot carry independent information on the sample spatial distribution, owing to different signal dependence (linear in Raman and quadratic in hyper-Raman) on the incident light intensity. This information can be quantitatively analyzed to recover the incident light intensity distribution at the focal plane. A superresolution vibrational image is then derived by the constrained deconvolution of the images by the obtained incident light intensity distribution. This method has been applied to a TiO? nanostructure and the obtained superresolution image was compared with a scanning electron microscopy image. The spatial resolution achieved by the present method is evaluated to be 160 nm, which is more than twice better than the diffraction limited resolution.     

Self‐assembly and structure formation in liquid crystalline phthalocyanine thin films studied by Raman spectroscopy and AFM

This work presents an investigation of films prepared by doctor blade casting, the formation of self‐assembled microstructures of a liquid crystalline phthalocyanine with highly oriented molecules. Raman Spectroscopy in combination with atomic force microscopy is applied to study the structures within the films. By keeping the substrate at room temperature or at 353 K during coating, different geometric structures namely rods and islands form. Rod‐like structures are growing in coating direction, whereas directional growth of the islands is not observed. The distribution of the rod lengths varies widely, whereas the width appears more uniform. Annealing of the samples shows a different behavior of the two textures. Islands tend to melt, and rods smooth their structural form, which is extracted from Raman imaging in combination with atomic force microscopy. Additionally, Raman imaging gives insight into laterally different relative crystallinity. These observations are discussed in the context of the molecular orientation as probed by polarized Raman spectroscopy. These polarized Raman spectra indicate azimuthal alignment of the molecules within the rods (edge on alignment). This alignment occurs along and also perpendicular to the growth direction. In contrast to the alignment in the rods, the molecules inside the islands occurring at higher temperature do not show preferential molecular orientation. After annealing, no preferential molecular orientation is observed in rods because of the loss of anisotropy, too. Copyright © 2012 John Wiley & Sons, Ltd.     

Modulation of optical pulses under electromagnetically induced transparency conditions: transfer of the Rabi oscillations manifestation from the radiofrequency to the optical range

The relative intensities of lines in resonance Raman scattering spectra of isolated skatole and skatole-water complex have been calculated quantum mechanically. The influence of the intermolecular interaction on these spectra has been considered. Particular features of the intensity distribution in the resonance Raman scattering spectra of indole and skatole have been compared.