KDP晶体拉曼散射角度特性

利用群理论详细分析了磷酸二氢钾(KDP)晶体的拉曼振动模式,得出了其拉曼振动模的归类。并采用拉曼光谱仪测量了Z切退火KDP晶体X(ZZ)珡X,Z(XY)珚Z和Y(XY)X三种散射配置和未退火KDP晶体Z(XY)珚Z配置下的拉曼光谱。根据拉曼选择定则得出X(ZZ)珡X,Z(XY)珚Z和Y(XY)X散射配置下的拉曼峰分别对应A1,B2(LO),B2(TO)对称类振动模,但在Z(XY)珚Z配置下的拉曼光谱中除了B2模,还观察到了A1模,而在Y(XY)X配置下的拉曼光谱中只有B2模,且退火和未退火晶体Z(XY)珚Z配置下的拉曼光谱无明显差别,此结果表明KDP晶体的对称性降低,在背向散射时A1模也具有角度特性,但与晶体的内应力无关,这是由KDP晶体内部结构决定的。     

Ge-Sb-Se硫系玻璃拉曼增益特性研究

本文制备了As_2S_3,As_2Se_3,Ge_(20)Sb_(15)Se_(65)和Ge_(28)Sb_(12)Se_(60)(mol%)四种硫系玻璃,测试了样品的折射率,红外透过及拉曼光谱.利用自发拉曼散射理论,并结合测量的拉曼光谱数据,通过将硫系玻璃与石英玻璃样品的拉曼光谱作对比的方法计算了四种硫系玻璃的拉曼增益系数gR.结果表明:As_2S_3玻璃在340 cm~(-1)拉曼频移处gR为60×10~(-13)m/W,As_2Se_3玻璃在230 cm~(-1)拉曼频移处gR为223×10~(-13)m/W,与文献报道结果基本相符.与传统光纤拉曼增益系数实验测定法相比,此方法为探索新型高拉曼增益的硫系玻璃组成提供了极大的便捷,应用此方法,计算得出Ge_(20)Sb_(15)Se_(65)和Ge_(28)Sb_(12)Se_(60)玻璃在200 cm~(-1)拉曼频移处的9R值分别为215×10~(-13)m/W和111×10~(-13)m/W.以上结果表明,不含有毒As元素的Ge-Sb-Se硫系玻璃其增益系数可达普通石英玻璃的200倍以上,为环境友好型拉曼光纤激光器基质材料提供了一种全新的可能.     

农药辛硫磷的密度泛函理论计算及拉曼光谱分析

辛硫磷(Phoxim)是一种高效、低毒、低残留有机磷杀虫剂,能抑制胆碱酯酶活性.辛硫磷的分子构型用Gauss View 5.0构造,理论计算采用密度泛函理论(density functional theory, DFT)的B3LYP/6-31+G(d, p)基组计算农药辛硫磷的拉曼光谱,实验上则采用分辨率为2 cm~(-1)的三级显微拉曼光谱检测仪对辛硫磷-甲醇溶液,辛硫磷乳油进行拉曼光谱检测.将理论拉曼光谱与实验拉曼光谱进行对比,其中有几个对应比较一致的拉曼光谱峰分别位于667, 745, 997, 1025, 1298, 1588 cm~(-1)处.首次报道了辛硫磷的拉曼光谱,同时对辛硫磷在600～1800 cm~(-1)区间的拉曼光谱进行了指认,指出了其在相应的频移位置产生较强拉曼光谱的分子振荡模式.     

光量子计数器在激光拉曼光谱仪中的应用

在1928年,印度科学家Raman发现了拉曼效应,并应用于光谱分析中。拉曼散射的光强大约是激发光的10~(-6)～10~(-8)量级,检测小信号的方法最常用的有直流放大器,锁相放大器,单光子计数器,Boxcar方法,多道分析仪(OMA)等等。拉曼光谱仪一般采用直流放大器和光子计数器检测拉曼信号。法国JOBIN-YVON公司的T-800型激光拉曼光谱仪检测拉曼散射光就是采用直流放大器     

胞嘧啶分子拉曼光谱研究

本文通过实验测量了胞嘧啶的常规拉曼光谱,有四个弱拉曼峰在以前胞嘧啶的常规拉曼光谱中未检测到。采用密度泛函(Density Function Theory)B3LYP/6-31+G(d,p)计算了胞嘧啶分子的拉曼光谱。结合理论计算结果对实验拉曼光谱振动模式进行了指认,并对其中几个拉曼峰非常弱的原因进行了分析。     

Na2O-K2O-Al2O3三元系固体结构研究

制备了xNa₂O-(1-x)K₂O-Al₂O₃(x=0.33, 0.50, 0.66, 1)三元系固体,实验利用拉曼光谱技术获得了xNa₂O-(1-x)K₂O-Al₂O₃三元系固体的常温拉曼光谱和升温拉曼光谱,使用CASTEP软件优化晶体结构和计算拉曼光谱,获得了xNa₂O-(1-x)K₂O-Al₂O₃三元系样品的常温拉曼光谱,结果表明低波数区(100～400 cm^-1)的拉曼特征峰为Na—O键的振动。中波数区(400～700 cm^-1)的拉曼特征峰为铝氧四面体中桥氧键的振动。高波数区(700～1 000 cm^-1)的拉曼特征峰为Al-O_nb的振动。对三元系样品的拉曼特征峰进行有效归属。获得了0.5Na₂O-0.5K<...     

拉曼增益对三类有限背景解传输特性的影响

基于含有拉曼增益效应的自聚焦非线性薛定谔方程,数值研究了拉曼增益分别对Peregrine怪波(PS)、Akhmediev呼吸子(AB)和Kuznetsov-Ma孤子(KMS)传输特性的影响。结果表明:拉曼增益效应会使怪波、AB和KMS在时间方向上发生分裂,且拉曼增益系数越大,分裂速度越快;拉曼增益效应还会使三种孤子解传输距离方向上的峰值功率增大,相邻两最大压缩脉冲之间的距离缩短,且拉曼增益系数越大,最大峰值功率越大,相邻距离越小。     

链状硅酸盐矿物的拉曼光谱研究

本文基于密度泛函理论(DFT)的平面波赝势法,利用CASTEP计算模块对四种典型链状(铝)硅酸盐矿物进行拉曼振动活性与拉曼光谱的模拟计算,同时测定了矿物的拉曼光谱,确定了四种矿物拉曼振动谱峰的归属,并结合硅氧四面体应力指数(SIT)进行了分析。结果表明,CASTEP计算模块可以有效获知(铝)硅酸盐矿物特征结构的拉曼振动模式的归属;链状(铝)硅酸盐矿物硅氧四面体局域环境与SiOT非桥氧对称伸缩振动波数之间的关系仍可用SIT指数描述。     

基于XeF (C-A)激光激励的自发拉曼散射技术研究

针对自发拉曼散射技术应用于实际燃烧场参数测量时面临的主要技术难题,采用XeF(C-A)激光作为激励光源,开展了自发拉曼散射技术实验研究。通过分析拉曼散射过程对光源参数的要求,优化了XeF(C-A)激光器部分参数,建立了自发拉曼散射诊断系统,实现了气体介质主要组分浓度在线测量,对比了XeF(C-A)激光与主流激光作为拉曼散射光源的优缺点。结果表明:与现有主流光源相比,具有脉冲能量大、微秒级脉宽,位于可见光波段等特点的放电抽运XeF(C-A)激光非常适合用作自发拉曼散射激励光源。     

塑料光纤拉曼散射的研究

给出了聚甲基丙烯酸甲脂(PMMA)塑料光纤(POF)的一级受激拉曼散射光谱,研究了一级斯托克斯光谱特点,测试了它的阈值,带宽,分析了拉曼光谱的形成机制,并将塑料光纤的拉曼光谱和石英光纤的拉曼光谱进行了比较。     

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。     

苯并三唑表面配位化学的电化学现场拉曼光谱研究

用电化学现场表面增强拉曼光谱(SERS)研究了非水体系中苯并三唑(BTAH)在银电极表面的吸附及成膜行为,结果表明非水体系中BTAH的吸附行为随电位变化而不同。较负区间主要以中性分子形式吸附;中间电位区间主要以BTA-吸附并不可逆成膜。采用直接电化学合成技术模拟电极表面过程制备了苯并三唑与Cu, Ag, Fe, Ni和Zn等金属的配合物,并研究了中性配体三苯基膦(pph₃)对其配位过程的影响,所得产物的元素分析以及拉曼光谱研究表明pph₃的加入影响了Cu和Ag与BTAH的配位过程,并出现在最终产物中,而对BTAH与Ni, Fe和Zn的配位过程未产生影响,产物未出现pph₃。     

氯化亚锡吸附与配位作用下L-肌肽的表面增强拉曼光谱

利用在电极表面强化学吸附的氯化亚锡与被测有机/生物分子之间的相互作用,不仅可以有效消除被测分子的碳化和氧化现象,还可以获得特别的增强信号,可应用于反应活性强的有机/生物分子的表面增强拉曼光谱分析。还报道了肌肽的电化学表面增强拉曼散射(SERS)光谱的研究结果,重点考察了加入氯化亚锡前后和改变电极电势对肌肽吸附SERS光谱的影响。无氯化亚锡时,肌肽的SERS光谱存在严重的碳化信号的干扰;氯化亚锡存在下,调控电极电势可引起吸附的氯化亚锡与肌肽在电极表面发生配位作用,借助这种表面相互作用,可将肌肽固载于基底表面,从而获得L-肌肽的高质量表面增强拉曼光谱,完全消除碳化现象的干扰。     

Elimination of oxidation and decomposition by SnCl2 in the SERS study of pyridoxine on a roughened Au electrode

Severe interference from the oxidation and laser carbonization was encountered in the measurements of surface‐enhanced Raman scattering (SERS) spectra of pyridoxine (PN) on the roughened gold electrode. However, we found that high‐quality SERS spectra of PN could be obtained by the introduction of SnCl₂, which only has few Raman peaks at low wavenumbers. SnCl₂, as a good reductive, is capable of removing the oxidative species on the gold substrate and the dissolved oxygen in solution, and as a result lowering the open circuit potential (OCP). Sn(II) can also strongly chemically adsorb on the gold surface and interact with PN through coordination/chelation, such that not only to prevent PN from damage by the giant electromagnetic field for the ‘first‐layer’ effect, but also to give rise to very strong Raman scattering signals of PN where chemical enhancement plays an important role. Those are the main reasons for the elimination of the oxidation and decomposition of PN and for the high‐quality SERS spectra of PN. The way the SnCl₂ confines PN within the enhanced electromagnetic field by its ability of adsorption and coordination/chelation can be utilized to improve the routine SERS analysis of analogous type of reactive organic/biomolecules. In addition, this method has been successfully extended to the SERS measurements of PN on the substrates of roughened silver and copper. Copyright © 2008 John Wiley & Sons, Ltd.     

Adsorption of 1,2,4‐triazole on a silver electrode: surface‐enhanced Raman spectroscopy and density functional theory studies

The pH‐dependent surface‐enhanced Raman scattering (SERS) of 1,2,4‐triazole adsorbed on silver electrode and normal Raman (NR) spectra of this compound in the aqueous solutions were investigated. The observed bands in the NR and SERS spectra were assigned with the help of density functional theory calculations for model molecules in the neutral, anionic, and cationic forms and their complexes with silver. The Raman wavenumbers and intensities were computed at the optimized molecular geometry. Vibrational assignments of the SERS and NR spectra are provided by calculated potential energy distributions. The combination of experimental SERS results and density functional theory calculations provide an insight into the molecular structure of adlayers formed by 1,2,4‐triazole on a silver surface at varying pH values and enable the determination of molecular orientation with respect to the surface. Copyright © 2012 John Wiley & Sons, Ltd.     

金纳米粒子掺杂DNA-CTMA-DPFP薄膜的表面增强拉曼散射特性

采用柠檬酸三钠还原氯金酸和离子交换法制备金纳米粒子掺杂DNA-CTMA材料,利用钯催化反应合成9,9-二乙基-2,7-二-(4-吡啶)芴荧光染料(DPFP),将DPFP与DNA-CTMA混合后,旋凃制备金纳米粒子掺杂的DNA-CTMA-DPFP薄膜样品。通过吸收光谱、荧光光谱和拉曼光谱的测量,研究了薄膜样品的光学特性和表面增强拉曼散射(SERS)特性。实验结果表明,薄膜样品在300～360 nm的吸收主要来自DPFP,在500～700 nm的吸收来自样品中金纳米粒子的局域表面等离子共振;样品在370,386,408 nm处的荧光峰分别对应DPFP的S₁₀-S₀₀、S₁₀-S₀₁和S₁₀-S₀₂能级的电子振动跃迁;在785 nm激光激发下,薄膜样品的拉曼散射主要来自DPFP分子,随着金纳米粒子掺杂比的增大,DPFP分子的拉曼散射峰强度逐渐增强。因此,金纳米粒子掺杂DNA-CTMA薄膜适合作为多种染料分子的SERS基底。     

Metal–organic frameworks: a novel SERS substrate

We report the direct observation of surface‐enhanced Raman scattering (SERS) effect using metal–organic frameworks (MOFs) as substrates. Without the aid of any metal colloids or enhancing agents, the SERS signals of methyl orange (MO) adsorbed in MOFs were observed and even remained active if the organic linkers in MOFs were completely removed by high temperature and O₂ plasma treatments. It implies that the SERS active site is at the metal oxide clusters. The ultraviolet‐visible spectra of MO, MOFs, and MO–MOF complexes show that absorption peaks are far from laser excitation line. Thus, conventional resonance enhancement effect should be ruled out, and charge‐transfer mechanism is the most likely scenario responsible for the observed SERS effect. Density functional theory (DFT) was used to interpret the chemical enhancement mechanism and the adsorption orientation‐dependent SERS spectra in our observation. The preferred adsorption orientations calculated by DFT method are consistent with the observed SERS results. Copyright © 2013 John Wiley & Sons, Ltd.     

Raman and SERS study on cimetidine–metal complexes with biomedical interest

Cimetidine (cim) is one of the most potent histamine H₂‐receptor antagonists for inhibiting excessive acid secretion caused by histamine; it has been hypothesized that the therapeutic effects can be related to its interactions with metal ions. Raman spectra of the solid cim with Co(II), Cu(II), Ni(II) and Zn(II) metal complexes show that they can adopt two different structures: one is octahedral and the other, with Zn(II), is probably tetrahedral. The octahedral structure appears to be distorted both by the different metal ions as well as by the different anion present. The study was extended to very dilute solutions (ppm range) by using the surface‐enhanced Raman scattering (SERS) technique, mimicking the physiological concentrations of cim and its metal complexes. SERS spectra suggest that, upon the binding of cim to silver colloids, the formation of stable 1:2 cim–metal complexes is excluded, the formation of 1:1 adduct appearing more probable; in this product the metal reaches its total coordination shell by complexion with water molecules. To better explain the binding mechanism of cim to a metal (Ag) surface, we performed theoretical B3LYP calculations on cim alone as well as on cim bonded to an Ag₂ metal cluster in presence of water, observing a sufficiently good agreement between experimental and theoretical wavenumbers. Copyright © 2010 John Wiley & Sons, Ltd.     

四种D—氨基葡萄糖甘氨酸混配金属配合物与DNA作用的SERS光…

研究了四种Ｄ－氨基葡萄糖甘氨酸混配合金属配合物的表面增强喇曼光谱（ＳＥＲＳ），发现它们在角胶上的吸附方式基本相同，因而ＳＥＲＳ光谱也基本相似，并用ＳＥＲＳ光谱研究了它们与ＤＮＡ的相互作用，发现这四种化合物与ＤＮＡ的作用能力有很大不同，Ｃｏ（Ⅲ）ＧｌｕＧ是值得进一步研究的可能抗癌药物。     

Identification of species formed after pyridine adsorption on iron,cobalt, nickel and silver electrodes by SERS and theoretical calculations

The adsorption of pyridine (py) on Fe, Co, Ni and Ag electrodes was studied using surface‐enhanced Raman scattering (SERS) to gain insight into the nature of the adsorbed species. The wavenumber values and relative intensities of the SERS bands were compared to the normal Raman spectrum of the chemically prepared transition metal complexes. Raman spectra of model clusters M₄(py) (four metal atoms bonded to one py moiety) and M₄(α‐pyridil) where M = Ag, Fe, Co or Ni were calculated by density functional theory (DFT) and used to interpret the experimental SERS results. The similarity of the calculated M₄(py) spectra with the experimental SERS spectra confirm the molecular adsorption of py on the surface of the metallic electrodes. All these results exclude the formation of adsorbed α‐pyridil species, as suggested previously. Copyright © 2009 John Wiley & Sons, Ltd.