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91.
萘酞菁铅化合物的光限幅特性研究 总被引:6,自引:0,他引:6
应用调Q倍频ns/ps Nd:YAG脉冲激光,在波长为532nm,脉冲宽度为8ns,重复频率为1Hz的条件下,研究了溶于二甲基亚砜(DMSO)中的萘酞菁铅溶液的反饱和吸收和光限幅特性。实验表明,萘酞菁铅具有良好的光限幅特性,它的有效激发态吸收截面与基态吸收截面的比值约为15.21,大于萘酞菁铜。研究结果表明,萘酞菁铅的光限幅特性优于C60,激发态吸收是其主要的光限幅机理。实验结果证实了重原子效应可以通过增强系际跃迁而使三重态的反饱和吸收增强,从而提高光限幅的能力。 相似文献
92.
Fa-Qian Liu Rong-Xun Li Wei-Hua Li Guang-Ye Liu 《Journal of organometallic chemistry》2009,694(22):3653-118
Two isomorphous new candidates [M(μ4-pz25dc)]n (M = Cd, 1; Zn, 2; pz25dc = pyrazine-2,5-dicarboxylato) for nonlinear optical (NLO) materials have been synthesized hydrothermally and characterized crystallographically as pillared-layer three-nodal frameworks with one four-connected metal nodes and two crystallographically different four-connected ligand nodes. Their optical non-linearities are measured by the z-Scan technique with an 8 ns pulsed laser at 532 nm. These two coordination polymers both exhibit strong NLO absorptive abilities [α2 = (63 ± 6) × 10−12 m W−11, (46 ± 6) × 10−11 m W−12] and effective self-focusing performance [n2 = (67 ± 5) × 10−181, (13 ± 3) × 10−18 m2 W−12] in 1.02 × 10−41 and 1.05 × 10−4 mol dm−32 DMF solution separately. The values of the limiting threshold are also measured from the optical limiting experimental data. The heavy atom effect plays important role in the enhancement of optical non-linearities and optical limiting properties. 相似文献
93.
We report the preparation and investigation of nano colloidal solutions of Ge28Sb12Se60 chalcogenide glass based on nonlinear optical transmission by the open-aperture Z-scan technique, using nanosecond laser pulses, at the excitation wavelengths of 532 nm. The Z scan spectra reveal a strong non linear absorption (reverse saturable absorption) for the nano colloid Ge28Se60Sb12 solutions. Observation of optical limiting at excitation wavelength suggests the potential of these materials to be used as optical limiters. 相似文献
94.
Let X1,...,Xn be independent and identically distributed random variables and Wn = Wn(X1,...,Xn) be an estimator of parameter θ.Denote Tn =(Wn - θ0)/sn,where sn2 is a variance estimator of Wn.In this paper a general result on the limiting distributions of the non-central studen-tized statistic Tn is given.Especially,when s2n is the jacknife estimate of variance,it is shown that the limit could be normal,a weighted χ2 distribution,a stable distribution,or a mixture of normal and stable distribution.Applicati... 相似文献
95.
《Wave Motion》2016
Some new classes of constitutive relations for elastic bodies have been proposed in the literature, wherein the stresses and strains are obtained from implicit constitutive relations. A special case of the above relations corresponds to a class of constitutive equations where the linearized strain tensor is given as a nonlinear function of the stresses. For such constitutive equations we consider the problem of decomposing the stresses into two parts: one corresponds to a time-independent solution of the boundary value problem, plus a small (in comparison with the above) time-dependent stress tensor. The effect of this initial time-independent stress in the propagation of a small wave motion is studied for an infinite medium. 相似文献
96.
Experimental and numerical analyses of high voltage 4H-SiC junction barrier Schottky rectifiers with linearly graded field limiting ring 下载免费PDF全文
This paper describes the successful fabrication of 4H-SiC junction barrier Schottky(JBS) rectifiers with a linearly graded field limiting ring(LG-FLR). Linearly variable ring spacings for the FLR termination are applied to improve the blocking voltage by reducing the peak surface electric field at the edge termination region, which acts like a variable lateral doping profile resulting in a gradual field distribution. The experimental results demonstrate a breakdown voltage of 5 kV at the reverse leakage current density of 2 mA/cm2(about 80% of the theoretical value). Detailed numerical simulations show that the proposed termination structure provides a uniform electric field profile compared to the conventional FLR termination, which is responsible for 45% improvement in the reverse blocking voltage despite a 3.7% longer total termination length. 相似文献
97.
本文综述了关于熵数和非紧性的测量的插值性质,本文也描述了经典结果及几个非常新的结果。 相似文献
98.
99.
Signorini Raffaella Meneghetti Moreno Bozio Renato Brusatin Giovanna Innocenzi Plinio Guglielmi Massimo Negra Federico Della 《Journal of Sol-Gel Science and Technology》2001,22(3):245-253
Hybrid organic-inorganic materials are investigated as suitable materials for inclusion of fullerene derivatives and for fabrication of laser protection devices. A specific synthesis has been developed in order to optimize non-linear optical performances of fullerene derivatives. 3-glicydoxypropyltrymethoxysilane has been used as an inorganic and organic network former to obtain the host material. The sol-gel synthesis consists of the hydrolysis and condensation in acidic conditions of the inorganic network. Epoxy polymerization has been achieved by using zirconium or BF3 alkoxides precursors. Bulk and multilayer materials doped with a fullerene derivative have been fabricated. They show good optical requirements: high fullerenes concentration, high microstructural homogeneity, high laser damage threshold and high optical limiting efficiency. Optical limiting (OL) mechanisms have been investigated. The most effective in the sol-gel materials is the reverse saturable absorption (RSA) one. However, different mechanisms, like non-linear (NL) scattering and NL refraction contribute to a different extent. Open- and closed-aperture OL and z-scan measurements on sol-gel samples show the contribution of NL scattering and NL refraction at 690 nm. Laser damage threshold has been characterized as a function of the structure of the samples and of the optical configurations (f/66 and f/5). 相似文献
100.
A procedure for pH-metric determination of the limiting adsorption of OH groups (A
OH) by FeIII, ZrIV, CrIII, and InIII oxyhydroxide hydrogels from 0.1 and 1.0 M solutions of NaCl is described. Data on the molecular area occupied by a single OH group on the hydrogel surface (S
OH) and the S
spec values, which were calculated from A
OH and S
OH, are presented. The S
spec value does not depend on the pH of hydrogel precipitation; the true S
spec value can be determined only from sorption of the OH groups at the actual point of zero charge of the hydrogel. The A
OH values for hydrogels were found to change only slightly during aging of hydrogels in electrolyte solutions. 相似文献