一种用于玉米品种鉴别的近红外光谱频率选择方法

提出了一种近红外光谱的频率选择方法用于玉米品种鉴别。首先确定一种衡量特征鉴别能力的准则函数,然后根据该准则函数逐步选出适合于分类的特征频率,并通过去除各频率特征之间的相关性使得优选出的频率特征包含尽可能多的品种类间差异信息,优先选择方差较大的频率特征以减弱噪声的影响。实验结果表明,频率选择大幅度地改善了识别效果,仅使用30维频率特征即可达到94.16%的识别率。随机模拟实验显示,优选出的频率特征的识别效果对频率的小幅随机扰动不敏感,验证了本方法的鲁棒性。     

Sensitive H(2) detection by use of thermal-lens Raman spectroscopy without a tunable laser

A new nonlinear Raman spectroscopy technique for trace-gas detection was proposed and demonstrated. The technique involved the use of a thermal-lens detection scheme to monitor thermal emission from the stimulated Raman process. We termed this technique thermal-lens Raman spectroscopy, and it was combined with a novel scheme involving a nonlinear Raman spectroscopy without a tunable laser. This technique was applied to detecting trace hydrogen molecules in the atmosphere by use of a pulsed Nd:YAG laser and a continuous-wave He-Ne probe laser. A detection limit of 9 parts in 10(6) was attained.     

Multiwavelength distributed-feedback dye laser array and its application to spectroscopy

A multiwavelength, multistripe tunable laser array is proposed, and its application to absorption spectroscopy is demonstrated. Laser waveguides doped with Rhodamine 6 G dye were integrated on a plastic chip, and simultaneous output at different wavelengths was obtained by use of a distributed-feedback technique. A very low threshold of 3 muJ was attained, and spectrally narrowed output (<0.1 nm) was obtained. A scheme for digital spectroscopy is also proposed based on this laser array, and absorption spectroscopy of sodium atoms without wavelength scanning is demonstrated by use of a sodium-vapor cell.     

相关光谱法检测甲烷浓度的研究

提出了一种基于相关光谱法的甲烷检测方案,在传统相关光谱法和差分吸收技术的检测理论的基础上,综合两者的优点提出了一种新的实现方案.合理的选择实验器材,构建了一个新的光纤甲烷检测系统.该系统不仅消除了待测气体中干扰气体引起的光强波动,而且也消除了周围环境的影响和光源光谱波动引起的干扰.     

Evaluation of residual iron in carbon nanotubes purified by acid treatments

A detailed analysis by X-ray photoelectron spectroscopy was carried out on multi-walled carbon nanotube (MWCNT) surfaces after non-oxidative and oxidative purification treatments in liquid-phase. The MWCNT were produced by pyrolysis of camphor and ferrocene, that provides a high yield but with high iron contamination (∼15% wt). The elimination and/or oxidation of iron nanoparticles were monitored by Fe2p and O1s core level. Oxygen-based functional groups attachment was also investigated by C1s fitting. The effectiveness of each treatment in iron removal was evaluated by thermogravimetric analysis (TGA) and atomic absorption spectroscopy (AAS). The integrity of the MWCNT structure was verified by Raman spectroscopy (RS) and transmission electron microscopy (TEM). A purity degree higher than 98% was achieved only with non-oxidative treatments using sonification process.     

Dynamics of iron in Fe-porphyrin aggregates studied by X-ray absorption and Mössbauer spectroscopy

The iron-porphyrin aggregates were studied by optical absorption and fluorescence method, infrared spectroscopy, X-ray absorption and Mössbauer spectroscopy. The aggregation of porphyrin molecules strengthens the Fe-ligands bonds and accelerates the spin-spin relaxations. A significant speeding-up of relaxation was observed with lowering the temperature down to 25 K. The comparison of the EXAFS (Extended X-ray Absorption Fine Structure) and Mössbauer spectroscopy results enabled some separation of the individual Fe vibration from its collective movement with ligands.     

黄铁矿处理重金属废水的光谱表征

将反射光谱和吸收光谱用于黄铁矿处理酸性重金属废水的研究,探讨了黄铁矿的表面反应以及黄铁矿与重金属的相互作用。漫反射红外光谱分析证实,在处理废水过程中,黄铁矿中表面羟基与重金属离子发生反应;并通过考察黄铁矿中碳酸盐,合理解释了黄铁矿处理酸性重金属废水后的溶液自然均趋于中性(pH 7)的现象。可见区的反射光谱用于表征处理过程中的黄铁矿的颗粒及比表面变化,解释了黄铁矿在重复使用时其活性反而增强的原因。吸收光谱及XPS表征表明,黄铁矿处理含Cr(Ⅵ)废水,是一个由Cr(Ⅵ)到Cr3+再到Cr(OH)₃的吸附沉淀过程。     

化学反应飞秒相干动力学与激光相干控制——1999年诺贝尔化学奖介绍

文章主要介绍了１９９９ 年诺贝尔化学奖得主艾哈默德·泽维尔（Ａｈｍｅｄ．Ｈ．Ｚｅｗａｉｌ） 教授的获奖工作———用飞秒技术和飞秒光谱的方法研究化学反应飞秒相干动力学,叙述了它们的原理、方法和应用,并简要介绍了其获奖背景、重要意义、相关研究及应用展望．     

一种实现光声光谱的导数光谱的新方法

提出了一种实现光声光谱的导数光谱的新方法,为了获得光声光谱的导数光谱,利用一台单色仪和一个分光棱镜研制成一个波长-光强分束器,并用这个波长-光强分束器同时获得两束光强相等而波长有微小差别的两束光,这两束光经过一个互补调制器调制后在光声探测器内叠加,可以实现光声信号的差分,扫描单色仪的波长,就可以获得光声吸收光谱的导数光谱。实验证明这种方法可以准确实现光声光谱的一阶导数光谱,而且导数光声光谱比光声吸收光谱具有更高的光谱分辨率。     

利用多轴差分吸收光谱技术反演对流层NO2

介绍了基于多轴差分吸收光谱技术(MAX-DOAS)反演对流层NO2的方法.利用差分吸收光谱技术(DOAS),扣除太阳夫琅和费结构及Ring效应的影响,拟合得到了大气中NO2的差分斜柱浓度dSCD,结合不同观测方向的测最结果分析得到了对流层大气中NO2的差分斜柱浓度(△SCID),结合辐射传输模型SCIATRAN计算得到了大气质量因子(AMF),并进一步计算得到了对流层NO2的垂直柱浓度(VCD)信息.为确保数据的准确性和可比性,将计算结果与长光程差分吸收光谱仪(LP-DOAS)的测量结果进行对比,二者具有较好的一致性,其相关系数R2分别为0.940 27和0.969 24.     

利用近红外光谱进行玉米杂种优势类群划分的可行性研究

准确地划分玉米杂种优势群,可有效地指导种质的改良、杂种优势模式的构建和新品种的选育。目前主要利用系谱法、配合力测定、同工酶和分子标记等进行玉米杂种优势类群的划分,这些划分方法成本高,操作复杂,甚至有的方法还需破坏种子。本文探索了利用近红外光谱技术(NIRS)快速、无损地划分玉米杂种优势群的可行性。使用MPA型傅里叶变换近红外光谱仪漫反射模式采集整粒玉米种子的光谱,用滑动平均窗口平滑、一阶差分导数、矢量归一化对光谱进行预处理。将光谱用主成分分析方法降维到低维空间,使用层次聚类法对A组6个中国的骨干自交系和B组的6个优良自选系共12个材料进行杂种优势群划分,结果将A组6个自交系划分为3类,A1(郑58)和A2(掖478)为一类,A3(昌7-2)和A4(黄早四)为一类,A5(Mo17)和A6(四F1)为一类,这与系谱法分析结果高度吻合。对B组6个自选系,将B1和B2,B3和B4,B5和B6分别划分为一类,与SSR标记的类群划分结果一致。由此可见,利用NIRS划分玉米杂种优势类群是简便、快速、高效、可行的方法。     

红外光谱法测定感冒咳嗽颗粒中的蔗糖含量

以感冒咳嗽颗粒为原料,通过傅里叶变换红外光谱仪为检测手段,提出并建立一种简便、快速、不使用任何有机溶剂的蔗糖定量分析方法。准确称取蔗糖对照品,以铁氰化钾作为内标物,通过溴化钾压片制样,配制成标准系列,测定FT IR吸收光谱。选择蔗糖中不受干扰的特征吸收峰羰基峰和铁氰化钾中的特征吸收峰氰基峰,通过蔗糖特征峰吸光度与铁氰化钾特征峰的吸光度的峰高之比与其对应浓度进行线性回归分析,从而获得校准曲线。结果表明,方法的线性范围为0.04—34.56m g/g,其线性回归的相关系数r=0.9932,样品测定回收率为97.8%—101.6%,相对标准偏差小于5%。该方法准确,可靠,适合于其他蔗糖类物质的快速定量分析。     

水体痕量重金属Ni的激光诱导击穿光谱测量研究

以1 064nm波长Nd∶YAG脉冲激光为激发光源,采用高分辨率、宽光谱段的中阶梯光栅光谱仪和ICCD为谱线分离与探测器件,实验研究了水体中痕量镍元素的激光诱导等离子体光谱发射特性和检测限;为了延长水体中金属元素的激光等离子体光谱发射时间、提高光谱检测灵敏度并减小ns激光作用下水滴溅射的影响,实验中以固体圆饼状石墨块为样品基体进行元素富集,通过在基体表面固定区域滴定固定量的已知不同浓度的硝酸镍溶液,烘干并制备待测样品。研究表明,镍的最佳探测延迟时间在700ns左右,元素谱线强度随着样品浓度的增加而增大并在较低浓度下呈现良好的线性关系,计算得到水体中Ni元素的痕量检测限为0.28,研究结果为进一步开展水体痕量重金属的激光诱导击穿光谱测量提供了方法。     

红外吸收光谱法快速分析甲基苯丙胺毒品中的添加成分

本文初步建立了甲基苯丙胺毒品中添加成分的红外光谱快速分析方法。将甲基苯丙胺毒品与淀粉、葡萄糖、咖啡因、非那西汀等按一定质量比例混合,然后利用傅里叶变换红外光谱仪进行红外光谱分析,得出红外光谱图。由于各种成分均有其特征的红外吸收,因此通过其特征吸收可以区分甲基苯丙胺毒品中所添加的成分,同时,通过吸收峰的强度可以大致判断添加成分的含量范围。红外光谱法不需要进行样品的前处理,具有快速、无损的特点。应用于实际案例中,获得了理想的结果。     

Admittance spectroscopy of spray-pyrolyzed ZnO film

A ZnO film was deposited using the spray pyrolysis method. The admittance spectroscopy method was used to establish the contributions to electrical behavior from grains, grain boundaries, and electrodes of film. Proper equivalent electrical circuit of a ZnO film composed of a single parallel resistor, capacitor, and inductor network connected with a series resistance was proposed. Moreover, we displayed metal-semiconductor transition (MST) in the ZnO film via admittance spectroscopy.     

Interaction of human serum albumin with N-(4-ethoxyphenyl)-N′-(4-antipyrinyl) thiourea using spectroscopies and molecular modeling method

The interaction between N-(4-ethoxyphenyl)-N′-(4-antipyrinyl) thiourea (EPAT) and human serum albumin (HSA) was studied by fluorescence spectroscopy in combination with UV absorption spectroscopy. The intrinsic fluorescence of human serum albumin was quenched by EPAT through a static quenching procedure. The binding constants of EPAT with HSA were estimated according to the fluorescence quenching results at different temperatures. The binding distance was obtained and the binding force was suggested to be mainly hydrophobic force, which was in accordance with the study of molecular model. The effect of common ions on the binding constants was also investigated. A new fluorescence spectroscopy assay of the proteins is presented, and results were very satisfactory.     

基于可调谐多模二极管激光吸收光谱的二氧化碳浓度测量

可调谐二极管激光吸收光谱技术(TDLAS)具有高分辨率、高灵敏度和快速测量等特点,是气体探测中的主流技术。使用多模二极管激光器作为光源,将多模二极管激光吸收光谱技术与关联光谱技术相结合有助于提高测试可靠性和稳定性,同时还可有效解决单模二极管激光器长时间工作时中心波长随外界温度或机械特性的变化而发生偏移的问题。以1 570 nm多模二极管激光器为光源,利用多模二极管激光关联光谱和波长调制的气体测量技术(TMDL-COSPEC-WMS),通过计算待测气体和参考池气体之间二次谐波信号峰值高度之间的关系,实现了对二氧化碳浓度的测量。实验中二氧化碳浓度测量范围在0.6%～30%之间,计算结果表明,二氧化碳浓度与真实浓度值之间具有良好的线性关系,其线性度为0.998 7,线性拟合的斜率为1.061±0.016 8。对二氧化碳与氮气混合气体的连续测量结果表明,系统的探测极限达到335 ppm·m,对同一样品在20 min内的20次连续测量的标准偏差为0.036 7%,表明了系统良好的稳定性,所有测量结果都显示了系统用于二氧化碳气体监测的有效性。     

Synthesis of germanium encapsulated fullerene

A method has been described for encapsulating Ge in a fullerene cage using GeO₂ and a graphite composite rod as anode and graphite as cathode. Annealing in an inert atmosphere before arcing, and the amount of GeO₂ in the rod determined the yield of Ge doped metallofullerene. Solvent extraction using soxlet in inert atmosphere followed by calcination in air was used to isolate metallofullerene from the soot. The insertion of Ge inside the fullerene was proven by ultra violet–visible absorption spectroscopy, matrix assisted laser desorption ionization-time of flight mass spectroscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy.