共查询到20条相似文献,搜索用时 656 毫秒
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用飞秒脉冲激光作光源,利用泵浦--探测方法测量了9个不对称五氮齿大环金属配合 物的时间分辨光克尔效应的响应信号,据此得到了它们的三阶光学非线性极化率x^(3)1111=1.19-3.38×10^-13esu和分子二阶超极化率γ1111=8.0×10^-32-2.83×10^-31esu以及光克尔效应响应不大于165fs等信息,讨论了周边取代基,中心金属离子和共轭π电子数对配合物三阶光学非线性极化率 相似文献
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Z—扫描技术及其应用 总被引:3,自引:0,他引:3
文章介绍了Z-扫描技术的原理、特点及其应用,分析了单色Z-扫描法测量非线性折射系数和非线性吸收系数,以及双色Z-扫描法研究非简并非线性光学效应. 相似文献
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附加克尔介质Jaynes-Cummings模型的场熵演化 总被引:8,自引:0,他引:8
研究了附加克尔(Kerr)介质Jaynes-Cummings(J-C)模型场熵演化的动力学特性,讨论了克尔介质非线性相互作用以及失谐量对场熵演化的影响. 相似文献
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Following the idea of three‐wave resonant interactions of lower hybrid waves, it is shown that quantum‐modified lower hybrid (QLH) wave in electron–positron–ion plasma with spatial dispersion can decay into another QLH wave (where electron and positrons are activated, whereas ions remain in the background) and another ultra‐low frequency quantum‐modified ultra‐low frequency Lower Hybrid (QULH) (where ions are mobile). Quantum effects like Bohm potential and Fermi pressure on the lower hybrid wave significantly reshaped the dispersion properties of these waves. Later, a set of non‐linear Zakharov equations were derived to consider the formation of QLH wave solitons, with the non‐linear contribution from the QLH waves. Furthermore, modulational instability of the lower hybrid wave solitons is investigated, and consequently, its growth rates are examined for different limiting cases. As the growth rate associated with the three‐wave resonant interaction is generally smaller than the growth associated with the modulational instability, only the latter have been investigated. Soliton solutions from the set of coupled Zakharov and NLS equations in the quasi‐stationary regime have been studied. Ordinary solitons are an attribute of non‐linearity, whereas a cusp soliton solution featured by nonlocal nonlinearity has also been studied. Such an approach to lower hybrid waves and cusp solitons study in Fermi gas comprising electron positron and ions is new and important. The general results obtained in this quantum plasma theory will have widespread applicability, particularly for processes in high‐energy plasma–laser interactions set for laboratory astrophysics and solid‐state plasmas. 相似文献
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Lihui Peng Henk Merkus Brian Scarlett 《Particle & Particle Systems Characterization》2000,17(3):96-104
Image reconstruction of electrical capacitance tomography (ECT) is a typical inverse problem owing to non‐linearity and ill‐posedness. At the same time, progress towards the solution of this kind of problem has been made at good speed as a branch of mathematics in the past three decades. In this paper, most of the regularization tools developed for the inverse problem are applied to the reconstruction of various simulated images by ECT. The results show promise for ECT image reconstruction by regularization methods. The non‐linearity of the sensitivity matrix seems to be the major problem. 相似文献
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茶叶定性和定量近红外光谱分析方法研究 总被引:5,自引:0,他引:5
分别采集了茉莉花茶、苦丁茶、龙井和铁观音4个种类茶叶共120个样本,利用NIRSystems6500型近红外光谱分析仪对样本进行光谱测量,应用近红外光谱分析技术对茶叶进行定性和定量分析。采用主成分分析法,结合聚类分析法,对4种类别的茶叶进行定性鉴别,通过对不同光谱数据预处理方式和不确定因子系数进行比较,确立了最优定性判别定标模型。同时,采用修正的偏最小二乘法,比较不同光谱预处理方法对定标模型的影响,建立了茶叶中水分、茶多酚和咖啡碱含量的定量分析模型,并对未知样本进行预测。定性分析模型的种类识别准确率达到100%,定量分析模型的决定系数均大于0.91,相对分析误差RPD均大于3。结果表明,利用NIRS分析技术可以快速定性和定量分析鉴别茶叶的类别和成分含量。 相似文献
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不同生色团对聚合物薄膜全光开关效应的影响 总被引:6,自引:3,他引:3
在聚甲基丙烯酸甲酯(PMMA)中掺人不同的偶氮染料并制成薄膜样品,以调制的线偏振Ar^ 激光(514nrn,CW)作为控制光,He-Ne激光(632.8nm,CW)为信号光,研究了样品的光致双折射效应及全光开关效应。通过对样品的响应特性和全光开关效应进行比较,发现电子推拉势较强的生色团分子在控制光作用下,可以产生较大的光致双折射效应,但光响应速度较慢,其光致双折射效应以光致异构取向为主要机制;而对于具有较弱电子推拉势的生色团分子,其光致双折射效应则主要来自光致异构烧孔机制,虽然其光致双折射效应小,但光响应速度快。 相似文献
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Shu-Fang Zhang 《光谱学与光谱分析》2008,28(7):1630-1632
The authors developed a method for the determination of tea polyphenols. Phenanthroline is a sensitive regent for the determination of Fe2+, it can react with Fe2+ to form an orange complex in acidic solution. A new spectrophotometric method was proposed for the determination of tea polyphenols in tea samples based on that tea polyphenols could react with Fe3+ to produce Fe2+, and the orange complex would be formed by the reaction of Fe2+ with Phenanthroline in acidic solution. In the presence of positive iron surfactant CTMAB, the sensitivity of chromogenic reaction was improved. The work focused on the optimizing of experiment conditions such as wavelength of determination, buffer solution, surfactant, and the react time etc. At the maximum absorption wavelength of 510 nm, the apparent molar absorptivity was 0.88 x 10(5) L x mol(-1) x cm(-1), Beer's law was obeyed in the range of 4.00 to 32.00 microg x mL(-1) Polyphenols. The detection limit was 2.0 microg x mL(-1). This method was applied to the determination of polyphenols in tea samples with satisfactory results. The method has three merits, namely high level of accuracy and sensitivity, simplicity, and simple equipment. 相似文献
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用ICPAES法研究了绿茶和红茶对水溶液中镉(Ⅱ)、铅(Ⅱ)的捕集行为,考察了时间、pH、温度等因素的影响。结果表明,绿茶对水中镉(Ⅱ)、铅(Ⅱ)的捕集30min基本达到平衡,而红茶的捕集平衡时间约为60min。当pH<4时捕集率随pH值减小而显著降低,当pH>4时捕集率变化趋缓;当pH<6时茶样对铅(Ⅱ)的捕集率大于镉(Ⅱ),而当pH>6之后则正相反,这与不同酸度的溶液中茶叶的带电状态及镉(Ⅱ)、铅(Ⅱ)的形态分布有关。升高温度有利于绿茶对镉(Ⅱ)、铅(Ⅱ)的捕集,而红茶变化不大;捕集后的镉(Ⅱ)、铅(Ⅱ)在25℃下用水洗脱困难,其中绿茶与铅(Ⅱ)的相互作用较强。 相似文献
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Note on Scattering of Electromagnetic Waves by Nonlinearly Screened Dust Grains in Plasmas 下载免费PDF全文
V. N. Tsytovich 《等离子体物理论文集》2015,55(9):664-670
Although most experiments in complex plasmas correspond to non‐linear grain screening, the theoretical models of non‐linear screening have not been checked experimentally. Scattering of electromagnetic waves on a single nonlinearly screened dust grain in plasmas can serve as one of effective methods for investigation of non‐linear screening. In present paper we have developed a theory for electromagnetic wave scattering that includes both the effect of coherency of scattering for long wave range and the loss of coherency with a decrease of the wave length. It is valid for arbitrary non‐linearity in screening and demonstrates that the loss of coherency occurs for wave length less then the characteristic screening length for non‐linear screening being usually substantially larger than the linear Debye screening length. The effect is illustrated numerically using the most popular model of non‐linear screening. The dependence of the cross‐section of scattering on parameter of non‐linearity in screening is calculated numerically. The loss of coherency in scattering by a single grain can serve as effective diagnostic for checking the theoretical models of non‐linear screening. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献