TDLAS分析仪谱图微缓形变的复原算法

为了减小谱图的微缓形变对TDLAS气体分析仪精度的影响,提出一种传递复原方案.该方案通过比对校验气体的出厂校准谱图和现场测量谱图,得到其形变系数;由于校验气体与过程气体间拥有相同的形变机制,根据形变的传递性可将过程气体的实时谱图也复原到校准状态,从而维持分析仪的保真度.解决了动态过程气体谱图形变的复原问题,不需调节光学和电子系统硬件参数,通过信号滤波、特征提取、形变系数计算,使用拉格朗日插值公式或Sinc函数插值法复原.在仿真实验中,传递复原的谱图与校准谱图的相似度达到99.999%.实验采集不同程度形变的CO_2气体谱图,采用拉格朗日插值复原算法的复原谱图与校准谱图的相似度达到99.9%.     

Incoherent inelastic neutron scattering from hexamethylene-tetramine and adamantane

The incoherent inelastic neutron scattering spectra of hexamethylene tetramine (HMT) and adamantane have been measured at high resolution between 200 and 1000 cm^-1. The agreement between the frequencies of the observed spectra and the optical spectra of Mecke and Spieseche (HMT) and Bailey (adamantane) is good. The observed neutron spectra are also matched very closely by the calculated one-phonon spectra, computed from a normal-coordinate analysis. There is some additional structure in the neutron spectra which appears to be due to multiphonon scattering involving lattice modes.     

The criteria for selecting a method for unfolding neutron spectra based on the information entropy theory

To further expand the application of an artificial neural network in the field of neutron spectrometry, the criteria for choosing between an artificial neural network and the maximum entropy method for the purpose of unfolding neutron spectra was presented. The counts of the Bonner spheres for IAEA neutron spectra were used as a database, and the artificial neural network and the maximum entropy method were used to unfold neutron spectra; the mean squares of the spectra were defined as the differences between the desired and unfolded spectra. After the information entropy of each spectrum was calculated using information entropy theory, the relationship between the mean squares of the spectra and the information entropy was acquired. Useful information from the information entropy guided the selection of unfolding methods. Due to the importance of the information entropy, the method for predicting the information entropy using the Bonner spheres' counts was established. The criteria based on the information entropy theory can be used to choose between the artificial neural network and the maximum entropy method unfolding methods. The application of an artificial neural network to unfold neutron spectra was expanded.     

熊果酸的Raman光谱和红外光谱结构特征比较

本文采用HRD2型双光栅单色仪测定了熊果酸的Raman光谱，得到熊果酸的特征Raman光谱结构，采用Philips 100型双光栅单色仪测定了熊果酸的IR光谱，得到熊果酸的特征IR光谱结构；解析了熊果酸的Raman光谱和IR光谱与其结构特征的关系，确定了熊果酸的Raman光谱的结构特征和官能团的归属，给出了熊果酸的两个基本骨架特征区域（A区：1386，1370，1363cm^-1，B区：1304，1269，1237cm^-1）；对熊甲酸的Raman光谱和IR光谱作了比较研究，指出Raman光谱具有比IR光谱更为丰富的结构信息的特征，并且，IR光谱的主要特征峰在Raman光谱中均有对应的谱峰；Raman光谱的谱峰形态清晰可变，使熊果酸的主要结构和官能团得到准确的分析和指认，与IR光谱一样，Raman光谱是天然药物解析的有效手段之一。     

八种鹅膏菌的傅里叶变换红外光谱的差谱鉴别研究

利用傅里叶变换红外光谱技术对长柄鹅膏菌、粗鳞白鹅膏菌、格纹鹅膏菌、红黄鹅膏菌、黄柄鹅膏菌、灰疣鹅膏菌、欧氏鹅膏菌、小豹斑鹅膏菌进行傅里叶变换红外光谱研究, 发现八种鹅膏菌的傅里叶变换红外光谱极为相似, 特征区和指纹区(1800~1100 cm-1)的相关系数均大于0.966。因此从这八种鹅膏菌的原始光谱对其鉴别将十分困难。通过差谱技术处理后, 八种鹅膏菌在1800~1100 cm-1范围呈现出各自的特征, 相关分析结果定量反映出它们之间差异较为明显。利用差谱中特征区和指纹区的差异可快速鉴别出该八种鹅膏菌。研究表明: 傅里叶变换红外光谱技术能提供大型真菌所含化学成分的分子结构信息, 结合差谱技术可以鉴别同属下的不同种高等真菌。     

微分谱结合独立成分分析对三维荧光重叠光谱的解析

多组分三维荧光重叠光谱是三维荧光光谱的数据解析中的难点之一。本文基于二维微分谱的计算原理, 充分利用三维荧光光谱具有激发光谱和发射光谱的特点, 获得了三维荧光光谱展开后的激发微分谱和发射微分谱. 之后利用独立成分分析对激发光谱或发射光谱的多组分混合微分谱分别进行解析, 得到了单一组分的激发微分谱和发射微分谱。其中三次样条插值有效的弥补了实测激发波长数据点少的缺点, 而粗糙惩罚平滑技术的引入则很大程度上减少了发射光谱的噪声,为微分谱的计算提供了有利的条件。单一组分的标准谱与解析谱的相似性系数的计算表明, 利用独立成分分析对微分谱进行解析更有利于多组分混合三维荧光光谱所含成分的识别。     

Recurrence Spectra of the Rydberg Hydrogen Atom near Two Parallel Metal Surfaces

Using closed orbit theory, we study the influence of the two parallel metal surfaces on the recurrence spectra of a hydrogen atom placed in the region between the two surfaces. The results show that the metal surfaces have significant effect on the photoabsorption process. Each resonance peak in the recurrence spectra is associated with one electronic closed orbit. In our work, we put the first metal surface at the critical value dc and vary the second metal surface. The results show that when the distances between the hydrogen atom and the two metal surfaces are close to the critical valuedc, the number of the closed orbits is the greatest and there are more peaks in the recurrence spectra. When the distance between the atom and the second metal surface is larger or smaller than dc, the number of the closed orbits decreases and there are fewer peaks in the recurrence spectra. The agreement between the semiclassical calculation spectra and the quantum calculation spectra suggests that our analysis is correct.     

从不纯样品的光谱中提取单一组分和结构的拉曼谱

X射线衍射谱和拉曼光谱均证实所用的SiC和GaN样品为不纯的非晶样品。通过新采取的减去经加权的“杂质”光谱的方法,从不纯的非晶样品的拉曼光谱中获取了纯非晶SiC和GaN的拉曼光谱,并由理论计算的声子态密度与减去“杂质”光谱的拉曼光谱很好相符,进一步证实减去“杂质”光谱的拉曼光谱确实是非晶拉曼光谱,从而表明新采用的扣除加权“杂质”光谱的方法是正确和具有广泛应用价值的。     

两模腔场谱间的量子干涉

研究了高Q腔中单个二能级原子与两模二项式光场依赖强度耦合相互作用系统的腔场谱,给出了弱初始场条件下的数值结果,讨论了两模光场之间的量子干涉对腔场谱结构的影响. 发现当两模光场的频率差Δ>g（g为原子与腔场间的耦合常数）时,两模光场间的干涉效应对谱结构没有影响,系统的腔肠谱只是两模腔肠谱的简单叠加;当Δ≤g时两模腔场谱间的干涉比较明显. 在强初始场条件下,量子干涉效应可忽略. 关键词： 腔场谱 量子干涉 两模二项式光场     

基于残差分布度量的M矮星细分类研究

恒星光谱分类是天文数据处理中一项非常重要的工作,主要对海量光谱巡天数据按照其物理性质进行分类。利用残差分布度量的方法对LAMOST巡天中观测到的 M矮星光谱进行细分类研究。残差分布度量是一种光谱间的距离度量方法,计算光谱之间的距离时,先将两条光谱进行归一化处理,之后计算对应波长采样点处的残差,最终以残差分布的标准差作为光谱之间的距离。使用LAMOST DR2中释放的M矮星光谱进行细分类实验。实验结果表明,残差分布度量方法能比较准确地对M矮星光谱数据进行细分类。还研究了信噪比、离群点以及残差标准化系数等因素对分类结果的影响。     

荧光法研究木犀草素与人血清白蛋白的相互作用

用荧光光谱、同步荧光光谱和紫外吸收光谱方法,研究了木犀草素与人血清白蛋白（HSA）的相互作用。研究表明木犀草素对HSA有较强的荧光猝灭作用,根据不同温度下木犀草素对HSA的荧光猝灭作用,利用Stern-Volmer方程处理实验数据,表明木犀草素对HSA的荧光猝灭作用属于静态猝灭。根据Fōrster非辐射能量转移理论计算了木犀草素与HSA间的结合常数和结合位点数,求得了木犀草素与HSA间的结合距离r。热力学数据表明二者主要靠疏水作用力结合。同时用同步荧光光谱探讨了木犀草素对HSA构象的影响。     

东北黑土的光谱特性及其与土壤参数的相关性分析

选取我国东北黑土作为研究对象,研究其光谱特性并分析黑土主要参数与近红外光谱的相关性。通过比较东北黑土和北方潮土光谱特征的差异,显示当水分含量较高时,两种土壤的光谱特性差别不是很明显,当水分含量较低时,受土壤质地的影响,两种土壤的吸光度光谱及微分光谱均有很大差异。土壤水分值和吸收光谱有很大相关系数,土壤全氮与光谱呈现出了一定的相关性,提高土样全氮含量的方差,可以获得高的相关系数;由于黑土中有机质的含量很高,使基于土壤有机质的光谱吸收达到饱和,二者之间呈现较低的相关性。     

Automatic standardization method for Raman spectrometers with applications to pharmaceuticals

An effective and practical method, based on automatic peak detection, Lorentzian fitting, and polynomial fitting, is developed for aligning spectra, which can significantly reduce or eliminate systematic differences between Raman spectrometers. In this work, Lorentzian fitting of the experimental spectra is performed to precisely locate the peak positions. Then the standardization procedure is illustrated on the spectra of a chemical standard measured on primary and secondary instruments, and the spectra can be successfully aligned to each other after shift correction. It is shown that the similarity of pharmaceutical spectra acquired on three Raman spectrometers is then considerably improved after removal of the Raman shift difference. The result shows that the similarity of the spectra between primary and secondary spectrometers increases dramatically from about 0.8 to 0.95 after spectra standardization. This means that the proposed standardization method can effectively reduce or eliminate systematical errors and enhance spectral compatibility across different instruments. Copyright © 2014 John Wiley & Sons, Ltd.     

Energy and emission characteristics of superlattice quantum-cascade structures

Energy levels, wave functions, and matrix elements of optical dipole transitions have been numerically calculated for superlattice quantum-cascade structures. An expression for the gain has been obtained with regard to the complete set of energy levels in different models of spectral-line broadening. A universal relation between the gain and emission spectra for unipolar laser structures has been proposed. The effect of spectral broadening on the shape of emission spectra is estimated. The electroluminescence spectra are compared with the calculated spontaneous recombination spectra and good agreement between the results is shown.     

不同地区恐龙化石的显微激光拉曼光谱研究

研究了7个恐龙化石样品在较高波数段的显微激光拉曼光谱,化石样品来自不同地区并且属于不同的骨骼部位。显微激光拉曼光谱表明,这7个恐龙化石的拉曼特征峰的峰位十分相似,但峰形有差别。进一步的比较分析还发现,不同源地相同骨骼部位的拉曼峰峰形比较相似,例如不同地区的脊椎头化石图谱比较相似,肢骨头化石的拉曼峰峰形也比较相似。实验结果表明,在1 000～1 800 cm-1波数段内的拉曼特征峰,主要与原骨骼所属的部位有关,与化石的源地关系不太大。785 nm的拉曼光谱不能区分恐龙化石的源地,但可以在较小的地质区域内区分化石骨骼的部位。     

基于自编码网络流形学习的毛竹笋不溶性膳食纤维含量红外光谱建模

提出了一种结合自编码网络(AN)流形学习和偏最小二乘(PLS)法的红外光谱建模方法AN-PLS。AN-PLS方法首先用AN算法对红外光谱数据进行非线性降维,再结合PLS建立回归模型。利用该方法建立了毛竹笋中不溶性膳食纤维含量的近红外光谱和中红外光谱回归模型。结果表明,用AN-PLS方法建立的回归模型,比用其他常用光谱数据预处理方法结合PLS及用单独PLS算法建立的模型具有更小的预测均方根误差RMSEP和更高的决定系数R2,因此,AN-PLS具有较优的建模与预测能力,利用近红外光谱和中红外光谱技术结合AN-PLS建模,可实现毛竹笋中不溶性膳食纤维含量的准确测量。     

恐龙不同部位化石的激光拉曼光谱

应用波长为785nm的激光拉曼光对来自武定九厂地区的两个不同部位的恐龙化石样品研究测试,首次在1000 cm-1~1800 cm-1波数段得到碳氢物质的拉曼峰图谱。在该波数范围内,颈椎化石和尾椎化石都有强、弱两类特征峰。它们的强特征峰与源地关系不大,即同一地区的化石特征峰并不很相似。弱拉曼峰与围岩的拉曼峰相似。恐龙化石的强拉曼峰来源于生物遗体分解剩下的碳氢类物质成分,弱拉曼峰源于石化过程中外部填充物质的成分。     

Comparative Mössbauer study of short-range ordering in electrodeposited and rapidly quenched amorphous alloys

We have found significant differences between the low-temperature Mössbauer spectra of rapidly quenched and electrochemically prepared samples in the investigated cases even if the room temperature spectra were similar. In the spectra of electrodeposited alloys, a new component appears at low temperature. The results can be interpreted in terms of differences between the structures of rapidly quenched and electrodeposited anorphous alloys.     

激光大气等离子体光谱特性实验研究

报道了对波长为1．06μm的脉冲激光在气体样品中产生的等离子体进行光谱研究的结果。气体样品为一个标准大气压的纯氮、纯氧和空气,光谱探测范围为300～900nm。结果表明,各种气体样品的激光等离子体光谱均表现为连续谱和线状谱的叠加,文中分别给出了连续谱和线状谱的基本特征,讨论了这些特征与等离子体物理特性的关系,并分析了纯氮、纯氧与空气激光等离子体光谱之间的异同。给出了激光等离子体光谱的时间演化和空间分布的基本特征,并初步讨论了与这些特征相关的等离子体物理特性。这些结果有助于加深对激光等离子体特性和机理,特别是对等离子体产生后的弛豫过程和复合机制的了解。     

Determination of the relationship between theoretical vibrational frequencies and experimental IR absorbance bands in organic molecules: computational study of oxane,chromane and flavan

The most stable isomers of oxane, chroman and flavan as basic building blocks for flavonoids were determined by density functional methods. Excellent agreement between the theoretical vibrational frequencies and the experimental infrared (IR) absorbance spectra were obtained. Similarities and differences between the spectra of chroman and flavan were identified. The difference in the IR spectra of the two conformers of flavan, mainly related to the vibration of atoms near the stereogenic centre, makes it possible to distinguish between them. Copyright © 2013 John Wiley & Sons, Ltd.