光声光谱技术在层状物质的逐层分析研究中的应用——Ⅰ.光声相位精细谱技术

本文提出光声相位精细谱法(PAPFS)。通过对层状物初始态光声相位扫描和对由此产生的PAPFS曲线的解析,可获取各层与光学热学和空间坐标相关的有价值的信息。本文用该法对彩色相纸作了逐层分析,并将结果与电镜作了比较。与PAPFS相关的层状物光声理论将在本文第Ⅱ部分中涉及。     

光谱重置法在非局域空间光孤子研究中的应用

利用光谱重置法在数值上求解非局域非线性薛定谔方程,快速准确地计算出非局域非线性介质中空间光孤子的波形,并得到在不同非局域程度下形成孤子的临界功率和临界束宽的关系.研究结果表明,在任意非局域程度条件下都可以形成稳定的空间光孤子.在响应函数不同时分别与解析解进行对比,发现数值解和解析解只有在强非局域和弱非局域这两种极限条件下是一致的,并给出了对应解析解的有效范围.     

吡啶非谐振耦合(费米共振)的二维相关拉曼光谱研究

费米共振(FR)是一种广泛存在于分子内和分子间的分子振动耦合和能量转移现象。研究了吡啶与乙醇混合溶液中的吡啶分子内费米共振效应(ν1～ν₁₂,ν₁+ν₆～ν₈),发现了吡啶乙醇存在分子间氢键(O—H…N),通过费米共振参数变化和二维相关拉曼光谱(2DCRS)揭示了吡啶乙醇溶液相互作用机理。ν₁～ν₁₂,ν₁+ν₆～ν₈通过非谐相互作用引起能量转移,从而导致费米共振参数的变化。2DCRS可以提供更多费米共振信息,阐明了费米双峰的相互作用机制。     

维多利亚蓝B与DNA作用的共振光谱特性及分析应用

文章基于维多利亚蓝B与脱氧核糖核酸在弱碱性条件下共振光散射的增强效应。建立了一种测定DNA的共振光散射法。pH值在 9 0～ 10 5范围内 ,三羟甲基氨基甲烷和盐酸 (Tris HCl)缓冲溶液中 ,维多利亚蓝B与DNA分子作用 ,使共振光散射增强 ,存在二个共振光散射增强峰 ,其强度与DNA的浓度呈线性关系 ,线性范围为 0～ 3 0mg·L- 1 ,相关系数为 0 9978,检出限为 2 1 5 μg·L- 1 ,用于fsDNA合成样品的测定获得了满意的结果     

粗糙银电极上高铁血红素的非共振表面增强拉曼光谱研究

以632.8nm为激发线,研究了高铁血红素的非共振表面增强拉曼光谱。结果表明,高铁血红素的氧化和还原状态的拉曼谱图以B_(1g)振动模式为主;血红素以丙酸侧基直接吸附于电极表面,叶啉环则以垂直于电极表面的形式存在。B_(1g)振动模式v_(15)对血红素中心铁的氧化还原状态十分敏感,被指认为非共振条件下血红素氧化还原状态的特征谱峰。     

非局域克尔介质中空间光孤子的相互作用

研究了强非局域克尔介质中光束的演化规律，通过相位分析得到了空间孤子相互作用所满足 的非局域非线性薛定谔方程的简化近似模型，并获得了双光束传输的解析解.结果表明在传 输过程中相互作用的高斯光束的相位决定于它们的输入总功率.以振幅一强一弱共同传输的 高斯光束为例进行了具体研究，得到了强光和弱光的解析式，相位分析显示弱光在相当短的 传输距离之内能产生大的相移，可以通过对强光能量的调控来实现对弱光的相位调制. 关键词： 非局域克尔介质 空间光孤子 孤子相互作用 相位调制     

太赫兹时域光谱技术在气体探测中的应用(英文)

太赫兹辐射是一种新型的远红外相干辐射源,近年来在不同的研究领域得到了广泛的应用。本文简要介绍了THz时域光谱技术;阐述了THz辐射应用于气体光谱的研究及其进展;比较了傅立叶变换,线性预测编码及小波变换算法在气体探测中的应用     

Si(100)和蓝宝石(0001)衬底上3C-SiC的Raman研究

单晶Si和蓝宝石(0001)是两种重要的3C-SiC异质外延衬底材料，然而，由于Si及蓝宝石和3C-SiC之间大的晶格失配度和热膨胀系数失配度，在3C-SiC中会产生很大的内应力，直接影响3C-SiC的电学特性。Raman散射测试是一个功能很强的测试方法，其强度、宽度、Raman位移等有关Raman参数可以给出有关SiC晶体质量的信息，其中包括内应力。利用背散射几何构置的Raman方法研究了Si(100)和蓝宝石(0001)村底上LPCVD方法生长的SiC外延薄膜，在生长的所有样品中均观察到了典型的3C-SiC的TO和LO声子峰，在3C-SiC／Si材料中，这两个声子峰分别位于970．3cm-l和796．0cm-1，在3C-SiC／蓝宝石材料中，分别位于965．1cm^-1和801．2cm-1，这一结果表明这两种外延材料均为3C-SiC晶型。利用一个3C-SiC自由膜作为无应力标准样品,并根据3C-SiC／Si和3C-SiC／蓝宝石的TO和LO声子峰Raman位移相对于自由膜的移动量，得到3C-SiC中的内应力约分别为1GPa和4GPa。实验发现在这两种材料的TO声子峰的Raman位移移动方向相反，通过比较3C-SiC、Si和蓝宝石的热膨胀系数，预期Si衬底上的3C-SiC外延膜受到的应力为张应力，而蓝宝石衬底上3C-SiC受到的应力则为压应力。     

空间偏移拉曼光谱技术的发展及应用

传统拉曼光谱只能探测样品的表层信息,或者只能穿透透明的表层探测样品内部,对多层不透明或不透明包装的样品检测则不适用了,比如搜索隐蔽的爆炸物、识别有包装的假药、无损检测骨骼疾病等。空间偏移拉曼光谱（SORS）技术是一种新型光谱检测技术,能够非侵入不透明包装或表层直接获得样品内部深层特征信息,这一技术的出现解决了上述的难题。首先详细介绍了SORS技术的工作原理：其根本原理在于光子迁移理论,其系统激光光源的入射焦点与光谱系统中收集透镜的焦点在待测样品表层空间上偏移一定的距离ΔS。当激光入射到待测样品表层时,表层样品被激发或散射出宽带荧光,其中有一部分散射光将到达样品内部,样品内部深层处产生的拉曼散射光子相比于样品表层的光子在散射过程中更易于横向迁移,经多次散射后返回样品表层被光谱仪器接收系统收集。到达样品内部不同深度ΔH的散射光返回表层后的位置距离激光光源入射点在样品表层上有不同的偏移距离ΔS。当空间偏移距离ΔS＝0时,激光光源入射点与拉曼光谱收集点重合,此处激发的光子密度最大,系统收集到的拉曼光谱信号大部分来自样品表层,样品深层拉曼信号被淹没;当空间偏移距离ΔS≠0时,光谱仪器收集到的拉曼光谱信号中来自表层的信号衰减很快,来自样品深层的信号衰减较慢,使得更深层的拉曼散射光子比重变大,从而实现光谱分离,再结合多元数据分析方法可以获得样品内部不同深层次的拉曼光谱,即空间偏移拉曼光谱。该技术具有很好抑制表层物质拉曼光谱和荧光光谱干扰的能力,特别适用于隐蔽在不透明包装材料下的物质拉曼光谱的提取,从而快速、非侵入地对目标物成分进行鉴定。其次介绍了SORS技术的特点。SORS技术是拉曼光谱的衍生技术,具备拉曼光谱技术的制样简单、水分干扰小、样品消耗量小、灵敏度高等全部优点,除此之外,有效抑制荧光、深层检测、非侵入无损检测、远距离检测等特点,这些特点有效提高了拉曼光谱强度,降低用户的检测和生产成本以及提高检测人员的人身安全。同时概述并对比了SORS技术现有的三种工作方式：标准SORS、逆SORS和倾斜SORS。标准SORS技术可进行远距离非接触测量,逆SORS较之标准SORS具有更高的灵敏度和抗光谱扭曲的潜力,而且入射的有效光照面和空间偏移距离ΔS是可控的,避免了样品过热;倾斜SORS具有较高的检测灵敏度,而且实验装置容易实现。然后在大量调研文献的基础上综述了近些年来SORS技术结合其他技术在化工生产、安检、生物医学、考古艺术、食品安全、稽查打假以及国防安全等多个领域的国内外发展和应用。最后指出了SORS技术目前存在的问题并展望了该技术未来的发展前景。     

Vibrational Spectroscopic Analysis of L,D-Dipeptides

Raman and infrared spectra of Boc-D-Leu-L-Leu-OMe, Boc-L-Ile-D-aIle-OMe and its N-deuterated derivative have been obtained. Normal mode frequencies on the models of these dipeptides have been calculated and the conformationally sensitive amide I, II, III and V modes are compared with the experimentally observed frequencies. The calculated frequencies are in good agreement with the observed frequencies. It is observed that the amide frequencies in these dipeptides are not very sensitive to their backbone conformation. This is in contrast to the well established conformational dependence of the amide modes in peptides, polypeptides and proteins. The normal mode calculations on these peptides also show absence of mixing in amide I and II modes, and hence lack of appreciable splitting in these modes due to transition dipole coupling.

     

氮化碳材料的光谱学分析及光催化性能研究

为克服光催化材料可见光利用效率低的缺陷,通过三聚氰胺高温缩聚的方法合成了石墨型氮化碳(g-C₃N₄)材料。采用XRD,SEM,UV-Vis技术对氮化碳材料的微观结构和光学性能进行了表征,并通过降解罗丹明B溶液研究了缩聚温度和不同光源对光催化效率的影响。结果表明,合成的氮化碳层片状结构保存良好,尽管材料表面在高温下断裂形成了不规则的块体颗粒;随着煅烧温度的升高,催化剂在紫外光和可见光部分的吸收都显著增强,这可能是由于材料表面的岩石状块体颗粒提高了材料的比表面积,同时降低了光的反射又提高了对光的吸收。在罗丹明B的光降解测试中,催化剂在可见光和太阳光照射下均表现出了良好的催化效果,缩聚温度为580 ℃时效果最好,分别为94.8%(60 min)和91.1%(90 min)。该方法制备的石墨型氮化碳催化剂对利用清洁能源进行环境净化应用具有极大的潜在价值。     

氮化碳材料的光谱学分析及光催化性能研究

为克服光催化材料可见光利用效率低的缺陷, 通过三聚氰胺高温缩聚的方法合成了石墨型氮化碳(g-C3N4)材料。采用XRD, SEM, UV-Vis技术对氮化碳材料的微观结构和光学性能进行了表征, 并通过降解罗丹明B溶液研究了缩聚温度和不同光源对光催化效率的影响。结果表明, 合成的氮化碳层片状结构保存良好, 尽管材料表面在高温下断裂形成了不规则的块体颗粒;随着煅烧温度的升高, 催化剂在紫外光和可见光部分的吸收都显著增强, 这可能是由于材料表面的岩石状块体颗粒提高了材料的比表面积, 同时降低了光的反射又提高了对光的吸收。在罗丹明B的光降解测试中, 催化剂在可见光和太阳光照射下均表现出了良好的催化效果, 缩聚温度为580 ℃时效果最好, 分别为94.8%(60 min)和91.1%(90 min)。该方法制备的石墨型氮化碳催化剂对利用清洁能源进行环境净化应用具有极大的潜在价值。     

Application of Spectroscopic Techniques to the Structural Analysis of Coal

Abstract

Coal is defined as an organic rock that is composed of macerals and minerals (Given, 1988). The macerals are believed to be derived from plant tissue that has been altered by microbial, thermal, and nonbiological processes in locales that are often referred to as “peat swamps.” One of the issues that often requires debate is the extent to which thermal processes have played in coal formation, and the extent of temperature increase during the metamorphosis of plant material to coal.     

Application of Spectroscopic Techniques to the Structural Analysis of Petroleum

INTRODUCTION

Petroleum, in the form of liquid oil or the solid asphalt, has been known for thousands of years (Speight, 1991) but, preceding the Industrial Revolution of the 19th century, its true potential was not realized. However, the advent of the Industrial Revolution caused man to turn from wood and coal to petroleum as the main source of liquid fuels. Furthermore, with the onset of the 20th century and the emergence of a technologically oriented society which has focused on the development of the automobile and the airplane, further uses have been found for petroleum products. Vast industries have emerged which rely upon the conversion of petroleum to a variety of by-products, and further uses for petroleumderived materials are still being addressed.     

Structural, Spectroscopic and Vibrational Properties for Low-Lying Electronic States of LiCl

A multireference configuration interaction(MRCI) study has been carried out on the LiCl molecule. The potential energy has been calculated over a wide range of internuclear separation for the 21 low-lying electronic states of the LiCl molecule dissociating into Li(2S,2P,3S)+Cl(2P). The(4)1Σ+,(3)1Π, 1-33Σ+, 1-33Π,1,3,1,3Σ,(5)1Σ+,(4)3Σ+,(4)1Π,(4)3Π excited states are studied for the first time in theory. Molecular spectroscopic constants(Re, De,ωe, ωeχe, Be and αe) have been derived for the 9 bound states(X1Σ+,(3)1Σ+,(2)3Σ+,1,3,1,3Σ,(4)1Π,(4)3Π) with a regular shape, and the spectroscopic constants of ground states X1Σ+are in good agreement with available experimental and theoretical values. The relative diferences between experimental values and our values for Re, De, ωe, ωeχe, Be andαe are 1.02%, 0.60%, 1.72%, 9.46%, 2.0%, and 0.75%, respectively. Moreover, vibrational levels of 9 bound states, which have not been investigated experimentally, are computed.     

Vibrational Spectroscopic Characterization of the Sulphate-Carbonate Mineral Burkeite: Implications for Evaporites

Burkeite formation is important in saline evaporites and in pipe scales. Burkeite is an anhydrous sulphate-carbonate with an apparent variable anion ratio. Such a formula with two oxyanions lends itself to vibrational spectroscopy. Two symmetric sulphate stretching modes are observed, indicating at least at the molecular level the nonequivalence of the sulphate ions in the burkeite structure. The strong Raman band at 1065 cm^?1 is assigned to the carbonate symmetric stretching vibration. The series of Raman bands at 622, 635, 645, and 704 cm^?1 are assigned to the ν₄ sulphate bending modes. The observation of multiple bands supports the concept of a reduction in symmetry of the sulphate anion from T _d to C _3v or even C _2v.     

Structural,Spectroscopic and Vibrational Properties for Low-Lying Electronic States of LiCl

A multireference configuration interaction (MRCI) study has been carried out on the LiCl molecule. The potential energy has been calculated over a wide range of internuclear separation for the 21 low-lying electronic states of the LiCl molecule dissociating into Li (²S, ²P, ³S)+Cl(²P). The (4)¹Σ⁺, (3)¹Π, 1-3³Σ⁺, 1-3³Π, ^1,3Δ, ^1,3Σ^-, (5)¹Σ⁺, (4)³Σ⁺, (4)¹Π, (4)³Π excited states are studied for the first time in theory. Molecular spectroscopic constants (R_e, D_e, ω_e, ω_eχ_e, B_e and α_e) have been derived for the 9 bound states (X¹Σ⁺, (3)¹Σ⁺, (2)¹Σ⁺, ^1,3Δ, ^1,3Σ^-, (4)¹Π, (4)³Π) with a regular shape, and the spectroscopic constants of ground states X¹Σ⁺ are in good agreement with available experimental and theoretical values. The relative differences between experimental values and our values for R_e, D_e, ω_e, ω_eχ_e, B_e and α_e are 1.02%, 0.60%, 1.72%, 9.46%, 2.0%, and 0.75%, respectively. Moreover, vibrational levels of 9 bound states, which have not been investigated experimentally, are computed.     

Vibrational Spectroscopic Studies of Molybdena Dispersed on Ceria Support

Abstract

Diffuse Reflectance Infrared Fourier Transform (DRIFT) and FT-Raman spectra have been used to investigate the interactions between molybdena and ceria in MoO₃/CeO₂ samples with different Mo loadings. The spectra exhibit a weak Mo=O broad band of surface species at ca. 920–970 cm^?1, which reveals that the interaction between dispersed molybdena and ceria could be mainly ionic in nature. With the increasing of Mo loadings, the observed Mo=O band broadening and frequency shifting are due to the overlapping and condensation of different hydrated surface species. On the basis of the measured surface dispersion capacity of morybdena and the structure of the preferentially exposed (111) plane of ceria, it is reasonable to suggest that the Mo⁶⁺ cations and the accompanying O²- anions are incorporated into the surface available vacant sites of CeO₂, accordingly the dispersed molybdena species are interacted electrostatically with the support instead of only physically dispersed on the surface of it.