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991.
Two-photon absorption excited intramolecular energy transfer and light-harvesting effects are demonstrated in three novel dendritic systems. These systems contain both an antenna structure that can effectively absorb two-photon energy at approximately 800 nm and emit fluorescence at approximately 515 nm and a core moiety that can absorb one-photon energy at approximately 520 nm and emit at approximately 590 nm. Covalently combining the core and antenna functionalities intrinsically changes the optical behavior of the component pieces. The two-photon energy absorbed by the antenna structure is resonantly transferred to the core, where the core's emission intensity is enhanced by 8, 20, and 34 times for the three dendritic systems. 相似文献
992.
He Ping LIU Xuan Yuan ZHENG 《数学学报(英文版)》2006,22(2):425-430
We consider the commutators of the HSrmander multiplier with CMO-functions on the Heisenberg group. The result of compactness on L^P spaces is proved. 相似文献
993.
We have tested and analyzed the properties of two-dimensional Position-Sensitive-silicon-Detector (PSD) with new integrated preamplifiers. The test demonstrates that the best position resolution for 5.5 MeV α particles is 1.7 mm (FWHM), and the best energy resolution is 2.1%, which are notably better than the previously reported results. A scaling formula is introduced to make the absolute position calibration. 相似文献
994.
在全原子力场模型的基础上,对向列液晶nCB(4-n-alkyl-4'-cyano biphenyls,n=5-8)进行了等压等温NPT系综下的分子动力学(MD)模拟.对MD的轨迹分析得到了二阶和四阶序参数以及描述液晶分子翻转运动的取向时间相关函数(TCF),并通过一个近似的单指函数对TCF拟合得到了相关时间.在此基础上,计算了nCB(n=5-8)的旋转扩散系数(Rotat ional diffusion coefficient,RDC).利用基于统计力学模型的Nemtsov-Zakharov方法和Fialkowski方法,分别计算了它们的旋转黏度系数(rotational viscosity coefficient,RVC),进而分别讨论了RVC,RDC和相关时间的奇偶效应.与文献中的实验结果比较表明,该方法得到了合理的计算结果和一致的奇偶效应. 相似文献
995.
996.
997.
In this paper, we propose a sinusoidal phase modulating (SPM) interferometer that is insensitive to external disturbances, and its measuring principle is analyzed theoretically. In the SPM interferometer, the interference signal is detected by a high-speed image sensor based on a low-speed CCD and a signal processing circuit is used to obtain the phase of each point on the surface. Therefore, the surface profile can be measured real-time. The experiments measuring the surface profile of a wedge-shaped optical flat show that the measurement time of the SPM interferometer is less than 10 ms, the repetitive measurement accuracy is 4.2 nm. The results show that the impacts of nonlinear distortion of the piezoelectric transducer (PZT) and part external disturbance are removed. 相似文献
998.
Ti films with a thickness of 1.6 μm (group A) and 4.6 μm (group B) were prepared on surface of silicon crystal by metal vapor vacuum arc (MEVVA) ion implantation combined with ion beam assisted deposition (IBAD). Different anneal temperatures ranging from 100 to 500 °C were used to investigate effect of temperature on residual stress and mechanical properties of the Ti films. X-ray diffraction (XRD) was used to measure residual stress of the Ti films. The morphology, depth profile, roughness, nanohardness, and modulus of the Ti films were measured by scanning electron microscopy (SEM), scanning Auger nanoprobe (SAN), atomic force microscopy (AFM), and nanoindentation, respectively. The experimental results suggest that residual stress was sensitive to film thickness and anneal temperature. The critical temperatures of the sample groups A and B that residual stress changed from compressive to tensile were 404 and 428 °C, respectively. The mean surface roughness and grain size of the annealed Ti films increased with increasing anneal temperature. The values of nanohardness and modulus of the Ti films reached their maximum values near the surface, then, reached corresponding values with increasing depth of the indentation. The mechanism of stress relaxation of the Ti films is discussed in terms of re-crystallization and difference of coefficient of thermal expansion between Ti film and Si substrate. 相似文献
999.
鸡粪堆肥水溶性有机物特征紫外吸收光谱研究 总被引:19,自引:0,他引:19
采用紫外-可见吸收光谱,对不同堆肥时期样品中水溶性有机物(DOM)的特征吸收参数进行了研究。结果显示,堆肥进行时样品DOM中的非腐殖质物质不断转化为腐殖质类物质,并且腐殖质物质的芳构化及分子量增加,腐殖化程度加大,同时苯环结构上的脂肪链降解成羰基、羧基等官能团。相关性分析显示,相同DOM浓度(DOC)样品在254与280nm的吸收值SUVA254,SUVA280,226~400nm吸光度的积分A226~400两两间均达到极显著正相关,与DOC均显著负相关,但以A226~400与DOC相关性最高;253和203nm吸光度比值E253/E203与SUVA254,SUVA280及A226~400均达到显著相关,但与DOC的相关性不如后三者;250和365nm吸光度比值E250/E365及465和665nm吸光度比值E465/E665与其他参数均不相关。分析结果表明,随着堆肥的进行DOM稳定度增加,对重金属配位能力增强;在所研究的紫外-可见光谱吸收参数中,A226~400最能反映堆肥腐熟度变化。 相似文献
1000.
By introducing a kind of new quantum state—Photon-added thermo invariant coherent state (PATCS), we discuss its nonclassicality
in terms of the negativity of Wigner function (WF) after deriving its analytical expression. It is found that the Wigner function
is related to Lagurre-Gaussian function. We then study the effect of decoherence (a thermal environment) on the PATCS according
to its WF (also related to Lagurre-Gaussian function). It is shown that it is not possible for WF to present the negative
region when the decay time
$\kappa t>\frac{1}{2}\ln \frac{2\bar{n}+2}{2\bar{n}+1}$\kappa t>\frac{1}{2}\ln \frac{2\bar{n}+2}{2\bar{n}+1}
. 相似文献