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高中数学教材(人教版,必修)的数列的通项公式的概念是“数列{an}的第n项an与项数n之间的关系可以用一个公式来表示,这个公式就叫做这个数列的通项公式”.有时又可以理解为第n项an关于正整数n的“函数”,即an=f(n)(n∈N*).这说明了数列与函数的关系;利用这个关系,我们可以从函数 相似文献
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Cd1-xMnxTe/CdTe superlattices and thin films were grown by molecular beam epitaxy on GaAs (001) substrates. Spectroscopic ellipsometry measurements were performed on Cd1-x Mnx Te/ CdTe superlattices with compositions x = 0.4, 0.8, and Cd1-xMnx Te thin films with x = 0.2, 0.4, 0.6 at room temperature in the photon energy range 1.4-5 eV. In superlattices the pseudodielectric functions measured by ellipsometry show specific features related to the exciton transition between quantized interbands. The exciton transitions related to the heavy holes of 11 H, 22H, and 33H are observed and identified. In thin films spectroscopic ellipsometry allows the clear identification of the energy gap Eo. Additionally, critical point transitions are observable in both the spectra of the superlattices and films. Photoreflectance spectra were also performed at room temperature in order to compare with our ellipsometry results. After taking into account the strain-induced and quantum confinement effects, the theoretical calculations are in good agreement with our experimental spectra. Ellipsometry appears to be a suited technique to monitor the MBE growth, ultimately also in situ, of diluted magnetic low-dimensional systems. 相似文献
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在70-300K温度范围内测量了组分x为0.01和0.04的Cd1-xFexTe及CdTe的法拉第效应随入射光子能量的变化,首次获得了Cd1-xFexTe在布里渊区Γ点和L点的有效g因子及其与温度的关系。给出了Fe2+离子与载流子间的sp-d交换作用常数N0(β-α)=(-1.57±0.03)eV。 相似文献
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测量了用热壁外延(HWE)生长的不同组分(0≤x≤0.98)的Zn1-xMnxSe薄膜在温度为300K下的反射光谱,用X射线能借测定样品实际的组分x值,由此获得了其能隙Eg与组分x的关系:在O<X<0.2组分范围,Eg随x的变化显示了反常现象,当X>0.2时,能隙Eg随x线性增大。在室温和低温下测量了样品的光致发光,除观测到Mn2+离子内部4T1→6A1发光峰外,在其低能边观测到一个较宽的发光峰,对结果进行了分析讨论。 相似文献
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高保偏聚合物光子晶体光纤的化学制备技术研究 总被引:14,自引:8,他引:6
研究了大尺寸高保偏聚合物光子晶体光纤(polymer Photonic Crystal Fibers,pPCFs)预制棒的化学原位制备技术.采用预聚物浇铸后加热聚合方法,成功制备了具有高保偏性能的光纤预制棒, 给出了聚合反应的最佳条件.对此预制棒进行二次拉伸及光学和化学性质的测试表明,该方法得到的预制棒力学结构稳定、光学透明度高,且拉伸所得光纤微结构保持完好、微孔坍塌率低、非固有损耗小.若在聚合反应体系中加入适量的激光染料或其它稀土有机螯合物等物质,可得到具有荧光性的高保偏聚合物光子晶体光纤预制棒,为保偏型聚合物光子晶体光纤激光器的研制提供新材料. 相似文献
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