5α-雄甾烷-3,17二-酮在一元溶剂中的红外光谱

在20种不同纯有机溶剂中,研究了5α-雄甾烷-3,17-二酮C3位和C17位羰基的红外光谱。将其羰基伸缩振动频率分别与经验溶剂参数如溶剂接受数AN、Brownstein的溶剂参数S和Schleyer线性自由能方程参数G值进行了相关分析。结果表明,C3位C=O在一元溶剂体系中出现2种谱带,而C17位C=O则出现3种谱带。羰基伸缩振动频率位移与AN值、G值具有较好的线性相关性,而在非醇溶剂中与S值线性相关较差。采用简单化合物丙酮分别对溶剂硝基苯、乙腈、二氯甲烷和氯仿的S值进行修正,并将复杂甾酮化合物5α-雄甾烷-3,17-二酮的羰基红外频率与S修正值进行线性分析,相关性良好。     

5α-雄甾烷-3,17-二酮在一元溶剂的红外光谱

在20种不同纯有机溶剂中,研究了5a-雄甾烷-3,17-二酮C3位和C17位羰基的红外光谱.将其羰基伸缩振动频率分别与经验溶剂参数如溶剂接受数AN、Brownstein的溶剂参数S和Schleyer线性自由能方程参数G值进行了相关分析.结果表明,C3位C=O在一元溶剂体系中出现2种谱带,而C17位C=O则出现3种谱带.羰基伸缩振动频率位移与AN值、G值具有较好的线性相关性,而在非醇溶剂中与S值线性相关较差.采用简单化合物丙酮分别对溶剂硝基苯、乙腈、二氯甲烷和氯仿的S值进行修正,并将复杂甾酮化合物5a-雄甾烷-3,17-二酮的羰基红外频率与S修正值进行线性分析,相关性良好.     

对氨基二苯甲酮光吸收和光反应活性的含时密度泛函研究

利用含时密度泛函理论研究了对氨基二苯甲酮(p-ABP )的气液相吸收光谱性质．结果表明，p-ABP单重态的性质随着溶剂极性的变化发生明显的改变．在极性溶剂乙腈、甲醇、乙醇、二甲亚砜和二甲基甲酰胺中，S1态是产生于π→π*跃迁的电荷转移态；在非极性溶剂环己烷和苯中，S1态是产生于n→π*跃迁的局域激发态．对于p-ABP三重态的计算结果表明，无论是极性溶剂中还是非极性溶剂中T1态都具有π→π*构型．不同溶剂中激发态构型和跃迁能的变化情况表明，对应于n→π*跃迁的吸收光谱随着溶剂极性的增加出现明显的蓝移，对应于π→π*跃迁的吸收光谱则随溶剂极性的增加出现明显红移．通过对计算结果进行分析，讨论了对氨基二苯甲酮三重态量子产率在不同溶剂中的变化情况和它在氢提取反应中表现出低光还原反应活性原因．     

γ-丁内酯溶剂效应的红外光谱

在19种不同有机溶剂中测定γ-丁内酯的红外光谱,研究溶质-溶剂间相互作用,并进行了溶质的羰基伸缩振动频率位移与溶剂参数相关性分析。结果表明,在所考察的溶剂(除正己烷和环己烷外)中,γ-丁内酯与溶剂间形成非键缔合物。缔合物的羰基伸缩振动频率(带)和游离γ-丁内酯的羰基伸缩振动频率(带)位移与溶剂参数AN、S值、ET(30)值、G值、Swain参数Aj和Bj以及LSER间具有较好的线性相关性。溶剂与γ-丁内酯相互作用中,溶剂的接受电子对的能力和极性起着重要作用。这意味着溶剂与γ-丁内酯形成非键缔合物时的主要作用力是氢键作用和偶极-偶极作用。     

溶剂对香豆素343染料光谱性质和最低激发态偶极矩的影响

通过对香豆素343(C343)在不同溶剂中的稳态吸收光谱、稳态荧光光谱和时间分辨荧光光谱的分析,研究了溶剂对C343的光谱性质的影响,并获得了光谱特性与溶剂极性之间的依赖关系. 吸收光谱峰值的红移随着溶剂极性的增加而发生较小的变化. 然而,荧光光谱的峰值对溶剂的极性却很敏感,并随着溶剂极性参数f(ε,n)的增加呈线性增长. 这是由于C343激发态电荷分布的变化导致了它在极性溶剂中第一激发单重态能级的变化. 用溶剂效应测量法和量子化学计算方法确定了C343最低激发态的偶极矩,这两方法所得的结果一致. C343在不同溶剂中的时间分辨荧光光谱研究表明荧光寿命随着溶剂极性的增加而增加,即从甲苯溶液的3.09 ns线性地增加到水溶液中4.45 ns;荧光寿命延长的根源可归因于C343与氢键给体溶剂之间的分子间氢键相互作用.     

两种薁磺酰胺席夫碱衍生物分子的光谱和热力学性质计算研究

使用密度泛函理论B3LYP方法,对两种薁磺酰胺席夫碱衍生物的分子结构、红外光谱、电子吸收光谱及热力学性质进行计算研究,并基于Tomasi的极化统一场模型(PCM)讨论电子吸收光谱的溶剂效应.结果表明,红外光谱计算值与实验值吻合,电子吸收光谱都是π-π*跃迁,溶剂及溶剂极性大小对最低能量吸收波长无影响.酚羟基的引入增大席夫碱的共轭体系,有利于提高分子的生物活性.298 K时,两种衍生物的ΔfHθm分别为5544.3,5304.6 k J·mol-1,ΔfGθm分别为20548.7,20331.2 k J·mol-1,Sθm分别为857.5,881.1 J·mol-1·K-1.     

确定酮、醛、醚和含氮化合物第二维里系数的新方法

本文提出了一套新的用来确定酮、醛、醚和含氮化合物第二维里系数的新方法。在新的非极性流体预估式的基础上,应用对比态原理,给出了酮、醛、醚和含氮化合物极性流体的优化参数,并对其进行了经验关联,使本预估式能应用于大部分非氢键,弱缔合效应的极性流体。并且仅仅需要临界温度、临界压力、偏心因子和对比偶极距作为预估参数。预估结果与最新的高精度的实验数据符合得很好。     

提纯溶剂对室温合成CsPbBr3量子点性能的影响

采用室温重结晶法制备CsPbBr_3量子点,分别利用六种常用的极性溶剂对量子点粗液进行高速离心提纯,监测提纯过程中每一步骤后的光致发光光谱,并采用吸收光谱,荧光寿命、X射线衍射分析和透射电镜等表征方法系统表征了六种极性溶剂提纯得到的CsPbBr_3量子点.研究表明,通过六种极性溶剂提纯,都可以得到结晶度良好的呈立方体形态的立方相CsPbBr_3量子点;在利用六种不同极性溶剂进行提纯过程中,第二次离心得到的上清液具有最为统一的半峰宽和峰值波长;除乙酸乙酯外,第二次离心得到的上清液具有最高的量子产出;比较而言,通过正丙醇、异丙醇、正丁醇特别是异丁醇提纯得到的CsPbBr_3量子点具有较高的发光性能.     

高山红景天中C24H30O8成分结构和性质的密度泛函研究

高山红景天系景天科红景天属草本植物,因其较好的疗效在医学上广泛应用.C24H30O8是一种从高山红景天中提取并已确认其结构的新的化合物.采用密度泛函理论(DFT)方法,在B3LYP/6-31G*水平下全优化得到了该化合物的分子几何构型和电子结构;依据Onsager自恰反应场(SCRF)模型考察了其在氯仿、丙酮、二甲亚砜及水等溶剂中的溶剂化作用;基于气相优化结构进行了B3LYP/6-31G*振动分析,用0.9613校正后的主要红外光谱与实验符合得很好.进一步按照统计力学原理求得了298~1000 K温度范围内该化合物的标准热力学函数(焓,熵,热容).     

核黄素在不同极性溶剂中的光谱特性研究

实验测得核黄素在水、二甲基亚砜(DMSO)和三氯甲烷三种不同极性溶剂中的稳态吸收光谱、荧光光谱和时间分辨荧光光谱,研究了溶剂对核黄素光谱性质的影响。实验结果表明,在不同极性的溶剂中,核黄素的吸收峰位置几乎不变,而荧光光谱峰值随着溶剂极性的增大而出现红移。这是由于溶质分子的电子激发及溶剂化效应引起的电子重新分布导致它在极性溶剂中第一激发单重态能级的变化。在时间分辨荧光光谱实验中,核黄素在水溶液中荧光寿命也高于在其他两种溶剂中,荧光寿命的延长可归因于核黄素与氢键对体溶剂之间的分子间氢键相互作用。应用Gaussian09软件,采用密度泛函理论和含时密度泛函理论,结合基于密度的溶剂化模型,对不同极性溶剂中的核黄素分子进行基态和激发态优化和计算。通过前线分子轨道分析,核黄素的受激跃迁属于苯环和含氮杂环上的π电子向苯环及C N,C O共轭双键的反键轨道π*的跃迁。分子偶极矩的计算结果表明,核黄素分子的第一激发态偶极矩大于基态偶极矩,偶极矩的增大,导致溶质与溶剂分子之间的相互作用的增大。而溶剂分子与溶质分子基态和激发态的相互作用程度不同,使得吸收峰和荧光峰出现不同变化情况。极性越大的溶剂越有利于对激发态的稳定作用,使激发态能量降低,相应的发射波长发生红移。最后,通过分子表面静电势和弱相互作用分析,在水溶剂中考虑氢键作用对核黄素分子光谱的影响。多聚体结构的理论吸收和发射峰值更接近实验结果,说明多聚体结构合理。水分子二聚体与核黄素形成的环状结构,有利于提高核黄素分子的刚性,有利于荧光的发射,减少非辐射跃迁的几率,荧光寿命延长。     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Research on beamforming method for dual-line array with space mismatch between the two line arrays

The performance of port/starboard discrimination of dual-line array will be seriously degraded when the space between the two line arrays of the dual-line array is mismatched. The directivity function of the delay-sum and delay-subtract beamforming is deduced and the port/starboard discrimination of the delay-sum and delay-subtract beamforming is also studied both under the ideal status and the status under which the space between the two line arrays of the dual-line array is mismatched. Analysis results show the delay-subtract beamforming has better performance of port/starboard discrimination. At last, the sea trial results demonstrate the theoretical results.     

Retrieval of ultraviolet skylight radiances and O3 slant column densities from balloon-borne limb spectrometer

With a novel light-weight and absolutely calibrated ultraviolet （UV） spectrometer, UV skylight radiances and O3 slant column densities are measured by balloon-borne limb measurements in Xinjiang area, China. UV skylight radiances measured at the height of 31 km are compared with the results from Modtran in the wavelength range from 290 to 420 nm. O3 slant column densities are derived from radiance spectra in the Huggins bands （320 - 335 nm） using differential optical absorption spectroscopy method. And the parameter exhibits a good correlation with the same value simulated by radiative transfer model （Tracy）. The O3 profile simultaneously measured by an O3 sonde is used as input in Tracy calculations. The O3 sonde is launched on the same balloon.     

Design optimization of highly sensitive LSPR enhanced surface plasmon resonance biosensors with nanoholes

For breaking through the sensitivity limitation of conventional surface plasmon resonance (SPR) biosensors, novel highly sensitive SPR biosensors with Au nanoparticles and nanogratings enhancement have been proposed recently.But in practice, these structures have obvious disadvantages.In this study, a nanohole based sensitivity enhancement SPR biosensor is proposed and the influence of different structural parameters on the performance is investigated by using rigorous coupled wave analysis (RCWA).Electromagnetic field distributions around the nanohole are also given out to directly explain the performance difference for various structural parameters.The results indicate that significant sensitivity increase is associated with localized surface plasmons (LSPs) excitation mediated by nanoholes.Except to outcome the weakness of other LSP based biosensors, larger resonance angle shift, reflectance amplitude, and sharper SPR curves' width are obtained simultaneously under optimized structural parameters.     

Polymer gratings based on photopolymerization for low-order distributed feedback polymer lasers

Novel polymer distributed feedback(DFB)gratings are fabricated based on photopolymerization to reduce lasing threshold of polymer lasers.A photopolymer formulation sensitive to 355-nm ultraviolet(UV)light is proposed for the fabrication of polymer gratings and it can be used to form polymer films by spin-coating process.A very low surface-relief depth ranging from 12.5 to about 1.0 nm has been demonstrated with a refractive-index modulation of about 0.012.The experimental results indicate that such polymer gratings have promising potentials for the fabrication of low-order DFB organic semiconductor lasers.     

A novel methodology for photometric compensation of projection display on patterned screen

We propose a novel methodology based on the projector-camera (ProCam) system to address the photometric compensation issue for the projection display on the patterned screen.The patterned screen is treated as the combination of a perfect white screen and a color modulator.The perfect white screen is used to automatically and accurately characterize the ProCam system offline using the polynomial model,and the parameters of the color modulator can be efficiently recovered by employing only two gray images based on the linear reflectance model.The experimental results show that the color artifacts of the display image can be greatly improved with this methodology,which demonstrates its feasibility and validity in the photometric compensation.     

Direction-of-arrival estimation using matrix spatial prefiltering approach

An approach to direction-of-arrival （DOA） estimation for multiple narrowband farfield signals is proposed. The technique uses a novel matrix spatial prefiltering approach. Specifically, a matrix filter is designed to spatially filter the incoming data snapshots. The un-wanted components arriving from the stopband angular sectors are attenuated and the desired components from the angular sector of interest pass with minimal distortion. The matrix filter spatially filters the element-space data and the output reserves the element-space data property, which makes it very useful by passing sensor data through a spatial prefilter prior to applying many other array processors to attenuate interferences and improve system performance. Several examples of DOA estimation problem are presented to illustrate the performance of the proposed spatial prefiltering approach. Results of simulation and real data show that the pre-filter can efficiently attenuate the spatial interferences and significantly improve the estimation and resolution capability of DOA estimators at low signal-to-noise ratios for the sources located inside the passband sector. In addition, the use of spatial prefilter makes it possible to estimate DOAs for multiple sources more than the number of the elements of an array.     

Quantum efficiency calibration of opto-electronic detector by means of correlated photons method

A new calibration method of detectors can be realized by using correlated photons generated in spontaneous parametric down-conversion (SPDC) effect of nonlinear crystal.An absolute calibration system of detector quantum efficiency is performed.And its principle and experimental setup are introduced.A continuouswave (CW) ultraviolet (351 nm),diode-pumped,frequency-doubled,and solid-state laser is used to pump BBO crystal.The quantum efficiencies of the photomultiplier at 633,702,and 789 nm are measured respectively.The coincidence peaks are observed using coincidence circuit.Some measurement factors including the filter bandwidth of trigger channel,the detector position alignment and polarization of the pump light are analyzed.The uncertainties of this calibration method are also analyzed,and the relative uncertainties of total calibration are less than 5.8%.The accuracy of this method could be improved in the future.