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61.
The emission spectra of naphthalene (NP)–triethylamine (TEA) systems were measured under steady-state illumination conditions in some protic and aprotic solvent-tetrahydrofuran (THF) mixtures. The fluorescence spectrum of the NP–TEA system in THF could be separated into two component bands (band A at 329 nm (fluorescence of NP) and band B at 468 nm (emission from an intermolecular exciplex)). The intensities of bands A and B decreased with increasing solvent polarity. The intensity of band B also decreased owing to the hydrogen-bonding interaction between TEA and protic solvents, but in this case the intensity of band A increased. The decrease in the intensity of band A with increasing solvent polarity is considered to be caused by the enhanced formation of an ion-pair parallel to the formation of an exciplex with increasing solvent polarity. The decrease in the intensity of band B is considered to be caused by the enhanced formation of ion-pair both parallel to and through the formation of the exciplex. The increase in the intensity of band A and the decrease in that of band B upon the addition of protic solvents is caused by the decrease in the concentration of free TEA. Acetonitrile only has a polar effect and trichloroacetic acid only has a hydrogen-bonding (protonation) effect, while alcohols have both the effects. 相似文献
62.
We present applications of polar plots for analyzing fluorescence lifetime data acquired in the frequency domain. This graphical,
analytical method is especially useful for rapid FLIM measurements. The usual method for sorting out and determining the underlying
lifetime components from a complex fluorescence signal is to carry out the measurement at multiple frequencies. When it is
not possible to measure at more than one frequency, such as rapid lifetime imaging, specific features of the polar plot analysis
yield valuable information, and provide a diagnostic visualization of the participating fluorescent species underlying a complex
lifetime distributions. Data are presented where this polar plot presentation is useful to derive valuable, unique information
about the underlying component distributions. We also discuss artifacts of photolysis and how this method can also be applied
to samples where each fluorescence species shows a continuous distribution of lifetimes. Polar plots of frequency-domain data
are commonly used for analysis of dielectric relaxation experiments (Cole–Cole plots), which have proved to be exceptionally
useful in that field for decades. We compare this analytical tool that is well developed and extensively used in dielectric
relaxation and chemical kinetics to fluorescence measurements. 相似文献
63.
Xiaojing Yang 《Journal of Mathematical Analysis and Applications》2004,299(2):494-507
In this paper we consider the solvability of the boundary value problem
64.
Bhaggy Duggal Robin Harte In Ho Jeon 《Proceedings of the American Mathematical Society》2004,132(5):1345-1349
``Polaroid elements" represent an attempt to abstract part of the condition, ``Weyl's theorem holds" for operators.
65.
极性分子型电流变液 总被引:2,自引:0,他引:2
电流变液在电场作用下软硬连续可调的奇特性质具有广泛和重要的应用价值。传统电流变液是基于颗粒极化产生的相互作用,根据介电理论预测,其剪切屈服强度的上限约为10kPa。电流变液被发明50年来,阻碍其应用的主要原因是剪切强度低。近年来发明的"极性分子型电流变液"是一类新型电流变液,其屈服强度比传统电流变液大一个数量级以上,且与电场强度呈线性关系,这一点和传统电流变液中的平方关系也明显不同。文章作者提出了极性分子在颗粒间强局域电场中的取向并与极化电荷作用的模型,成功地解释了观察到的实验现象。根据这一原理,有可能制备出屈服强度高达MPa的电流变液。 相似文献
66.
67.
介绍双螺旋叠栅条纹检测光束准直性的基本原理,进一步就双螺旋叠栅条纹的特征参量与被测光束发散角(即光束准直精度)的关系进行分析和推导。在分析双螺旋叠栅条纹进行时,首先采用频域低通滤波提取纯叠栅条纹,然后提取纯叠栅条纹的特征参量。提出两种特征参量的提取方法,一种依次进行傅里叶变换计算相位信息的傅里叶变换方法,另一种是受传统时间相移算法启发而提出的空间相移算法,讨论了在两种方法中极坐标的重采样问题和相应的计算公式,并进行了计算机模拟。结果表明,傅里叶变换方法和空间相移算法实质都是获取叠栅条纹全场趋势的平均值,使最终光束发散角的检测具有很高的精度,对自成像条纹周期的检测误差在±2.8‰以内。 相似文献
68.
Hawking radiation can be viewed as a process of quantum tunnelling near black hole horizon. When a particle with angular momentum
tunnels across the event horizon of Schwarzschild black hole, the black hole will change into a Kerr black hole. The emission
rate of the massless particles with angular momentum is calculated, and the result is consistent with an underlying unitary
theory. 相似文献
69.
Jaw-Yen Yang Tse-Yang Hsieh Yu-Hsin Shi Kun Xu 《Journal of computational physics》2007,227(2):967-982
A class of high-order kinetic flux vector splitting schemes are presented for solving ideal quantum gas dynamics based on quantum statistical mechanics. The collisionless quantum Boltzmann equation approach is adopted and both Bose–Einstein and Fermi–Dirac gases are considered. The formulas for the split flux vectors are derived based on the general three-dimensional distribution function in velocity space and formulas for lower dimensions can be directly deduced. General curvilinear coordinates are introduced to treat practical problems with general geometry. High-order accurate schemes using weighted essentially non-oscillatory methods are implemented. The resulting high resolution kinetic flux splitting schemes are tested for 1D shock tube flows and shock wave diffraction by a 2D wedge and by a circular cylinder in ideal quantum gases. Excellent results have been obtained for all examples computed. 相似文献
70.
Spacelike Willmore surfaces in 4-dimensional Lorentzian space forms, a topic in Lorentzian conformal geometry which parallels the theory of Willmore surfaces in S4, are studied in this paper. We define two kinds of transforms for such a surface, which produce the so-called left/right polar surfaces and the adjoint surfaces. These new surfaces are again conformal Willmore surfaces. For them the interesting duality theorem holds. As an application spacelike Willmore 2-spheres are classified. Finally we construct a family of homogeneous spacelike Willmore tori. 相似文献