光致发光光谱在鉴别不同类型珍珠中的应用

爱迪生珍珠和珈百丽珍珠为近年来相继问世的优质淡水有核珍珠,分别酷似南洋珠和AKOYA珍珠,如何区分白色珍珠、金色珍珠、黑色珍珠及银灰色珍珠的类型和颜色成因,成为目前检测机构棘手的难题。对132颗不同类型的白色系、黄色系、黑色系、灰色系天然呈色珍珠与染色或辐照改色的各类珍珠进行了系统的PL光谱测试分析,结果表明不同类型的珍珠PL光谱有重要鉴别特征,尤其是PL光谱中荧光背景强度(F)与565 nm文石主峰强度(A)比值F/A,可有效区分不同类型白色珍珠以及黑色、金色银灰色珍珠的颜色成因。（1）白色南洋珠F/A值多集中于1附近,白色爱迪生珍珠与白色珈百丽珍珠具有类似的PL光谱与F/A值变化范围,但大部分样品出现631 nm发光峰,F/A值多集中于2;白色AKOYA珍珠的F/A值大于10。（2）金色南洋珠的F/A值多集中于1.6,变化范围较小,染金色南洋珠与染金色爱迪生珍珠F/A值基本都大于4。（3）深灰色体色Tahiti黑珍珠没有特征的发光峰,但随着颜色加深,逐渐出现617 nm处发光峰,黑色体色Tahiti黑珍珠具有稳定的有机卟啉相关的617和650 nm处发光峰;而绝大部分染色、辐照的黑色珍珠样品并未出现明显的荧光背景增强现象,但缺失617和650 nm处发光峰。（4）天然呈色银灰色AKOYA样品F/A值都小于3,而染色和辐照成因的银灰色AKOYA的F/A值都明显高（1.79~144）,并且因改色方式不同,存在一定的变化范围。     

我国主要育珠贝（蚌）贝壳珍珠层及珍珠的激光拉曼光谱研究

本文对我国四种主要育珠贝（蚌）贝壳珍珠层拉曼光谱进行了系统研究,结果表明：1）大珠母贝贝壳珍珠层中未观察到有机质的任何拉曼峰;2）三角帆蚌及马氏珍珠贝贝珍珠贝贝珍珠层及其差殖珍珠的拉曼光谱中除由文石矿物引起的拉曼峰外,还可观察到明显的由全反式结构的类胡萝卜素引起的拉曼峰,根据其峰位推断分子中的C＝C双键的数目为10;3）企鹅珍珠贝贝壳珍珠层的拉曼光变中可观察到较复杂的有机质的拉曼峰,推测可能是由金属卟啉化合物引起的,但尚需进一步工作证实;4）珍珠层中类胡罗卡素及金属卟啉类化合物的相对浓度与珍珠层的颜色密切相关。贝壳珍珠层中有机质的拉曼光谱研究可为珍珠漂白及在食品、化妆品等领域的应用提供科学的依据。     

常见灰色珍珠的紫外可见漫反射光谱类型及其灰色成因

基于紫外可见（UV-Vis）漫反射光谱就当前市售流通领域常见的灰色珍珠品类进行表征并依据样品的反射谱图的类同特征予以分类,并初步探究了灰色珍珠的颜色成因。研究表明：(1)基于灰色珍珠的UV-Vis 漫反射光谱中约280 nm 处吸收峰的有无,首次将灰色珍珠分为Ⅰ型（存在明显的吸收）与Ⅱ型（无吸收或仅存在较弱的吸收）。并据Ⅰ型珍珠在其紫外可见光区的反射峰形与其反射主波长位置的差异进一步分为Ⅰn, Ⅰp与Ⅰf三个亚型,上述Ⅰ型珍珠均为有核珍珠。其中Ⅰp型珍珠的内核为白色、内核与珍珠层之间较多存在褐色、黑褐色的过渡层,该过渡层可能是导致珍珠呈灰色的直接原因。与此同时,上述Ⅰp型珍珠在宝玉石鉴定领域一般认为是未经处理的。（2）结合前人就珍珠辐照的相关工作及本工作中贝壳珍珠层辐照前后颜色的改变及UV-Vis反射光谱的变化特征, 推断辐照仍是人工处理导致珍珠呈现灰色主要原因之一。基于样品对应的UV-Vis反射光谱中约280 nm吸收峰的消失或仅呈现一吸收肩可初步定性该类珍珠经优化处理。同时,从Ⅱ类灰色珍珠的断面结构看,当前灰色珍珠并不仅局限于有核珍珠,无核灰色珍珠同样存在于流通领域。课题研究工作可为灰色珍珠及其优化处理品的鉴定提供理论与技术支撑。     

显微拉曼光谱在珍珠鉴定中的应用

本文用显微拉曼对三种珍珠 (天然海水珍珠、人工养殖海水珍珠、人工养殖淡水珍珠 )做了测试与分析。结果表明 :虽然主峰相同 ,然而这三种珍珠的拉曼谱有不可置疑的差别。另外 ,珍珠粉和整粒珍珠也有明显差异。测试中还发现 ,与拉曼谱同时记录到的光荧光谱也是有关珍珠的宝贵信息。因此 ,显微拉曼光谱仪记录到的材料振动谱和荧光谱为珍珠的分析研究及日常鉴定提供了可靠的信息资料。     

淡水和海水养殖珍珠的微量元素特征

珍珠中的微量元素有其特征规律及作用。前人很早就关注到淡水珍珠和海水珍珠微量元素特征的差异,但限于测试技术及分析方法,测出的微量元素种类相当有限,并且对测试结果也缺乏深入分析。电感耦合等离子体质谱议(ICP-MS)具有检测能力高, 速度快,可同时测试多种痕量及超痕量元素。采用ICP-MS对淡水和海水养殖珍珠的微量元素进行测定,并通过数据处理方法分析, 对比。结果表明：(1) 珍珠中含量较高的微量元素种类(Sr, Zn, Ni, Ba, Mn, Cr, Cu, Pb, Ti, Co, Ce, Zr, La, Rb)大致相同,但淡水养殖珍珠的微量元素总量明显少于海水养殖珍珠;(2) 淡水养殖珍珠的微量元素含量较为规律,具有较为固定的含量序列,即Sr>Mn>Ba>Ni>Cr>Pb;而海水养殖珍珠的微量元素含量差异较大,除了各样品都最富集Sr元素外,没有明显的含量顺序;(3) 珍珠中某些微量元素之间存在显著相关性。结论对养殖珍珠的环境指示, 养殖技术, 鉴定,以及综合开发利用具有一定的指导意义。     

彩色珍珠致色成分的拉曼光谱研究

对多种彩色珍珠样品进行了可见光光谱和拉曼光谱测试,研究了珍珠致色成分的种类及其与颜色的关系。研究结果表明：(1) 彩色淡水珍珠和海水珍珠样品均会在1 121～1 132和1 506～1 524 cm-1范围出现强峰,该特征峰归属于多烯化合物的C—C和CC伸缩振动;(2) 随着珍珠颜色的加深,样品位于1 117～1 132,1 502～1 524和2 000～3 500 cm-1范围的峰逐渐增强,特征峰所代表的有机质与珍珠颜色有关;(3) 深紫色淡水珍珠和深橘红色海水珍珠样品在1 475～1 575 cm-1范围的包络峰可分成8～10个次级峰,计算可知多烯化合物CC双键数目分别为N=9～27和N=7～27。珍珠中不同种类和含量的多烯化合物,可能是彩色珍珠的致色原因。     

我国主要育珠贝(蚌)贝壳珍珠层及珍珠的激光拉曼光谱研究

本文对我国四种主要育珠贝(蚌)贝壳珍珠层拉曼光谱进行了系统研究,结果表明1)大珠母贝贝壳珍珠层中未观察到有机质的任何拉曼峰;2)三角帆蚌及马氏珍珠贝贝壳珍珠层及其养殖珍珠的拉曼光谱中除由文石矿物引起的拉曼峰外,还可观察到明显的由全反式结构的类胡罗卜素引起的拉曼峰,根据其峰位推断分子中的CC双键的数目为10;3)企鹅珍珠贝贝壳珍珠层的拉曼光谱中可观察到较复杂的有机质的拉曼峰,推测可能是由金属卟啉化合物引起的,但尚需进一步工作证实;4)珍珠层中类胡罗卜素及金属卟啉类化合物的相对浓度与珍珠层的颜色密切相关.贝壳珍珠层中有机质的拉曼光谱研究可为珍珠漂白及在食品、化妆品等领域的应用提供科学的依据.     

不同处理工艺对珍珠的紫外可见漫反射光谱的共性影响研究

主要基于紫外可见（UV-Vis）漫反射光谱首次对比研究了经过热处理、有机或无机染料改色或钴-60产生的γ射线辐照三种不同处理工艺对同为珍珠质的淡水与海水珍珠及贝壳珍珠层的漫反射光谱的影响机制。结果表明：（1）在不同颜色、淡海水属性的珍珠与贝壳珍珠层的UV-Vis反射光谱的紫外区皆存在约280 nm 处的吸收峰,上述吸收峰位归属于珍珠层中自身存在的有机质所致,而非珍珠的致色色素。（2）以上三种不同的处理工艺对上述280 nm处的吸收峰位存在一致的影响行为,即随着不同的处理工艺强度的增大,处理样品对应的反射谱图中约280 nm处吸收峰的强度逐渐降低直至消失。与此同时,珍珠的反射谱图中紫外区的反射主波长的反射强度也随之减弱,且反射主波长的峰位向可见光区发生显著红移。研究工作可为珍珠及珍珠的优化处理的鉴定筛选及其珍珠颜色的形成属性判定提供检测依据与理论支撑。     

“爱迪生”珍珠及染色处理有核珍珠的谱学特征

颗粒大、圆度高并具有浓郁颜色的淡水有核养殖珍珠（商贸名称为“爱迪生”珍珠）为珍珠市场提供了更高的品质与价值,然而受利益的驱使,染色的有核养殖珍珠也逐渐流入市场,扰乱了消费者的健康消费,在一定程度上阻碍了“爱迪生”珍珠产业的良性发展。本文利用红外光谱仪、紫外-可见分光光度计和光致发光光谱仪对养殖和染色“爱迪生”珍珠进行了系统的谱学研究,并将其与海水珍珠、染色海水珍珠进行了比较。结果表明：（1）染色与养殖“爱迪生”珍珠在红外光谱上均显示1 445,882和725 cm-1处的文石振动峰,其中染色“爱迪生”珍珠在3 800 cm-1处均出现宽缓的弱吸收峰;（2）染色“爱迪生”珍珠的紫外可见光光谱中280 nm处的吸收峰明显弱于养殖“爱迪生”珍珠,染色后的“爱迪生”珍珠整体反射率降低,可能与染剂使珍珠中的蛋白质分子受损有关。染黄色“爱迪生”珍珠缺失养殖橙黄色“爱迪生”珍珠在360～380 nm处的吸收峰,而与染色海水金珠430 nm处的强吸收峰相似。染黑色“爱迪生”珍珠在425 nm处有吸收峰,染色海水黑珍珠在480和645 nm处有吸收峰,养殖海水黑珍珠在702 nm处有吸收峰,三者图谱的差异可能为各自的染料不同所致;（3）养殖“爱迪生”珍珠在光致发光光谱中450～550 nm范围内可见一组吸收峰,染色“爱迪生”珍珠的发光中心向红区偏移且在650 nm附近出现强度不等的与染色剂相关的吸收峰,染色海水金珠也在600 nm处有和染色剂有关的吸收峰。     

珍珠层独特的反射光谱特征及其成因

采用反射光谱、扫描电镜及理论模拟计算对大珠母贝珍珠层的结构色及微结构进行了系统的研究。结果表明:(1)大珠母贝珍珠层文石板片厚度从生长端到壳中区显著减小, 从540减至340 nm, 导致同级别反射峰波长呈现明显的蓝移现象;(2)大珠母贝珍珠层的结构色是由文石板片和蛋白质层构成的多层薄膜结构和黄色素的共同作用决定的。     

Synthesis and characterization of Cr doped CdS nanoparticles stabilized with polyvinylpyrrolidone

Undoped and Cr (2 and 4 at.%) doped CdS nanoparticles were synthesized in aqueous solution by simple chemical co-precipitation method using polyvinylpyrrolidone (PVP) as stabilizer. The prepared nanoparticles were examined using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDAX), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (DRS) and Fourier transform infrared spectroscopy (FTIR). XRD pattern of the nanoparticles showed cubic zincblende phase with the particle size of the order of 3-4 nm, which was in good agreement with the results obtained from TEM studies. The EDAX analysis confirmed that Cd, Cr and S elements were present in the samples and the variations between the target and actual compositions were microscopic. UV-vis DRS spectra of the samples exhibited decrease in the band gap which further attests the incorporation of Cr into CdS nanoparticles. FTIR studies revealed that the undoped as well as Cr doped CdS nanoparticles were capped by polyvinylpyrrolidone.     

Effect of lithium thiocyanate addition on the structural and electrical properties of biodegradable poly(ε-caprolactone) polymer films

Polymer electrolyte films of biodegradable poly(ε-caprolactone) (PCL) doped with LiSCN salt in different weight ratios were prepared using solution cast technique. The effect of crystallinity and interaction between lithium ions and carbonyl groups of PCL on the ionic conduction of PCL:LiSCN polymer electrolytes was characterized by X-ray diffraction (XRD), optical microscopy, Fourier transform infrared spectroscopy (FTIR) and AC impedance analysis. The XRD results revealed that the crystallinity of the PCL polymer matrix decreased with an increase in LiSCN salt concentration. The complexation of the salt with the polymer and the interaction of lithium ions with carbonyl groups of PCL were confirmed by FTIR. The ionic conductivity was found to increase with increasing salt concentration until 15 wt% and then to decrease with further increasing salt concentration. In addition, the ionic conductivity of the polymer electrolyte films followed an Arrhenius relation and the activation energy for conduction decreased with increasing LiSCN concentration up to 15 wt%. UV–vis absorption spectra were used to evaluate the optical energy band gaps of the materials. The optical energy band gap shifted to lower energies with increasing LiSCN salt concentration.     

Spectroscopic characterization analysis on Cr (VI) removal mechanism by low-cost adsorbent of rice husk ash

Analyzing methods of Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction analysis (XRD) and X-ray fluorescence spectroscopy (XRF) were used to reveal the adsorption mechanism of Cr(VI) by low-cost adsorbent of rice husk ash. Results of FTIR showed that amide II band, Si--O--Si, and (O--Si--O were important for Cr(VI) removal. SEM micrographs suggested that series of needle-shaped precipitation appeared on cell surface, and inorganic precipitation mechanism and redox mechanism might work in the test. XPS spectra showed that main elements of rice husk ash were C, N, O, P and Si, existing state of C was mainly aldoketones groups, coordi nation reaction existed between C functional groups and Cr(VI); N element, --NH2 in chief, could remove Cr(VI) in the way of physical adsorption based on electrostatic interaction; Si--O might be useful in adsorption process. XRD data suggested representative characteristic adsorption band of SiO2, and the increasing crystallinity of rice husk ash showed metallic compound formed between Cr(VI) and rice husk ash. XRF results indicated that the content of K, Na, Mg and Ca changed, and two new elements were detected, the evidence of ion exchange mechanism. The functional groups played different roles in Cr(VI) adsorption process, and inorganic precipitation mechanism, redox mechanism, surf-complexation mechanism and ion exchange mechanism were important ways in Cr(VI) removal, which could provide theoretical support in further application.     

低成本吸附剂稻壳灰对Cr(Ⅵ)去除机制的谱学表征

以低成本稻壳灰作为吸附剂,使用FTIR,SEM,XPS,XRD,XRF等分析手段,研究稻壳灰对Cr(Ⅵ)的去除机制。FTIR研究表明酰胺Ⅱ带,Si—O—Si,O—Si—O等在Cr(Ⅵ)去除过程中有一定贡献。由SEM图片清晰可见：吸附Cr(Ⅵ)后,稻壳灰表面分布有众多的光亮沉积物。XPS图谱证明：稻壳灰的主要组成元素为C,N,O,P和Si;C元素的存在状态以醛酮类为主,含C官能团与Cr(Ⅵ)发生了配位反应;N元素以—NH₂形态为主,Cr(Ⅵ)可能以静电作用与含N基团结合,并以物理吸附为主;Si的存在以Si—O为主,含Si官能团可能与Cr(Ⅵ)发生了配位反应。XRD分析结果表明：谱图中出现的峰是典型的SiO2特征峰;稻壳灰的结晶度增加,表明稻壳灰与Cr(Ⅵ)形成了具有晶体结构的金属化合物。XRF研究发现,K,Na,Mg和Ca的元素含量在吸附前后有所变化,另有两种新元素出现,这说明吸附过程存在离子交换机制。所有这些皆表明：各种官能团在Cr(Ⅵ)去除过程中的角色各不相同,无机微沉淀机制、氧化还原机制、表面络合机制、离子交换机制等是稻壳灰去除Cr(Ⅵ)的主要途径。这可以为吸附技术的实际应用提供理论支持。     

RbVO_3的光谱分析及能带结构研究

采用杂化前驱体的湿化学合成法制备了偏钒酸铷(RbVO3)发光材料。利用粉末X射线衍射(XRD)、红外光谱仪(IR)等对RbVO3的结构进行了表征,利用紫外-可见(UV-Vis)吸收光谱、光致发光光谱等研究了该发光材料的光致发光性能,并采用基于密度泛函理论的CASTEP程序计算了RbVO3的能带。结果表明,在357 nm紫外光的激发下,RbVO3产生发光峰在525 nm附近、色坐标为(0.318 0,0.430 9)的绿白光发射,发光亮度高;RbVO3计算的光学带隙为2.67 eV,与实验值较为吻合。     

Structural,morphological, optical and antibacterial activity of rod-shaped zinc oxide and manganese-doped zinc oxide nanoparticles

Pure ZnO and Mn-doped ZnO nanoparticles were synthesized by Co-precipitate method. The structural characterizations of the nanoparticles were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. UV–Vis, FTIR and photoluminescence (PL) spectroscopy were used for analysing the optical properties of the nanoparticles. XRD results revealed the formation of ZnO and Mn-doped ZnO nanoparticles with wurtzite crystal structure having average crystalline size of 39 and 20 nm. From UV–Vis studies, the optical band-gap energy of 3.20 and 3.25 eV was obtained for ZnO and Mn-doped ZnO nanoparticles, respectively. FTIR spectra confirm the presence of ZnO and Mn-doped ZnO nanoparticles. Photoluminescence analysis of all samples showed four main emission bands: a strong UV emission band, a weak blue band, a weak blue–green band and a weak green band indicating their high structural and optical qualities. The antibacterial efficiency of ZnO and Mn-doped ZnO nanoparticles were studied using disc diffusion method. The Mn-doped ZnO nanoparticles show better antibacterial activity when higher doping level is 10 at% and has longer duration of time.     

2-丙烯酰胺基-2-甲基-1-丙烷磺酸过渡金属化合物红外光谱研究

利用FTIR和X－射线粉末衍射方法研究了三种2－丙烯酰胺基－2－甲基－1－丙烷酸过渡金属化合物（Co^2 ,Ni^2 ,Cu^2 )。钴、镍两种化合物红外光谱与铜化合物存在明显差别。钴、镍两种化合物红外光谱相近,但晶体结构不同。     

红外和拉曼光谱的煤灰矿物组成研究

研究煤灰中矿物质的性质通常从矿物组成的表征入手。为了分析两种高硅铝煤灰的矿物成分,采用傅里叶变换红外光谱(FTIR)、拉曼光谱和X射线衍射(XRD)技术对煤灰样进行了测试和综合表征,将FTIR和拉曼光谱的分析结果与XRD进行了比较。FTIR结果表明,在1 100~1 000 cm-1范围内高硅铝煤灰出现最强的特征峰,例如石英峰(1 089 cm-1)和偏高岭石峰(1 042 cm-1),它们都归属于Si-O伸缩振动。对原始红外谱图进行二阶导数处理后,可获得重叠峰的峰位,有助于更完整的解析矿物吸收峰,从而获得更丰富的矿物组成信息。煤灰中硬石膏的红外和拉曼光谱发现,在1 157,1 126和674 cm-1的拉曼光谱峰与在1 151,1 120和678 cm-1的红外光谱峰振动模式分别相同且峰位接近,还存在一些完全不同的拉曼光谱与红外光谱峰,表明这两种光谱存在互补性。尽管煤灰中锐钛矿含量很低,但由于Ti-O的极化率很高,因此拉曼光谱显示锐钛矿的144 cm-1峰远远强于石英的461 cm-1峰。XRD结果表明,煤灰中主要存在石英、云母、赤铁矿、硬石膏和未知的无定形相矿物,FTIR和拉曼光谱综合分析的结果表明除了这些矿物,还存在偏高岭石、无定形氧化硅、长石、方解石和锐钛矿等。在定性分析方面,将FTIR和拉曼光谱结合起来比XRD单独获得的矿物组成信息更为详细。     

Influences of capping molecules on optical properties of nanocrystalline ZnS:Cu

ZnS:Cu nanocrystals capped with different capping molecules have been successfully synthesized by a simple aqueous method. The prepared nanocrystals were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive analysis by X-rays (EDAX). The surface characterization of the nanocrystals was done by FTIR spectroscopy. The effect of capping agents on absorption and photoluminescence (PL) spectra of the ZnS:Cu nanocrystals was studied. A blue shift of the absorption peaks was observed and attributed to a quantum confinement effect, which increases the band gap energy. The photoluminescence spectra of the capped ZnS:Cu nanocrystals showed a broad peak in the range of 460–480 nm. The intensity of the PL spectra strongly depended on the capping agents.     

Catalytic conversion of air-methane flow by nanostructured ruthenium dioxide: FTIR spectroscopy and modeling

Nanostructured powders of ruthenium dioxide RuO₂ were synthesized via a sol-gel route involving acidic solutions with pH varying between 0.4 and 4.5. The RuO₂ nanopowders were characterized by X-ray diffraction. Crystallite sizes measured from X-ray diffraction profiles and TEM analysis varied in the range 8-16 nm, with a minimum of crystallite dimension for pH 1.5. Catalytic conversion of methane by these RuO₂ nanostructured catalysts was studied as a function of pH, catalytic interaction time, air methane composition, and catalysis temperature, by the way of Fourier transform infrared (FTIR) spectroscopy coupled to homemade catalytic cell. The catalytic efficiency defined as FTIR absorption band intensities I(CO₂) was maximum for sample prepared at pH 1.5, and mainly correlated to crystallite dimensions. A modeling approach of catalytic conversion is proposed for such a specific experimental configuration.