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纳米晶稀土复合氧化物Dy0.5Sr0.5CoO3—Y的光谱特性研究 总被引:2,自引:0,他引:2
研究了纳米晶Dy0.5Sr0.5CoO3-Y的光谱特性。结果表明:当晶粒尺寸减小至纳米量级时,发射光谱的激子峰波长蓝移;XRD,FTIR谱表明,与体材料相比,纳米晶的衍射峰宽化,纳米晶的红外谱带大劈裂和宽化,表现为纳米尺寸量子化效应。 相似文献
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研究了纳米晶Dy0 5 Sr0 5 CoO3 Y 的光谱特性 ,结果表明 :当晶粒尺寸减小至纳米量级时 ,发射光谱的激子峰波长蓝移 ;XRD ,FTIR谱表明 ,与体材料相比 ,纳米晶的衍射峰宽化 ,纳米晶的红外谱带大劈裂和宽化 ,表现为纳米尺寸量子化效应。 相似文献
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本文讨论半导体超晶格及量子阱导带和价带的量子化亚带或子能级之间的带间光跃迁过程。所讨论的光跃迁过程或光谱研究方法有吸收光谱、光电流谱、光荧光和荧光激发谱、调制光谱以及喇曼散射光谱。关于亚带能量状态将着重讨论量子阱中的激子效应和价带亚带混和及其对带间光跃迁的影响。 相似文献
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本文讨论半导体超晶格及量子阱导带和价带的量子化亚带或子能级之间的带间光跃迁过程。所讨论的光跃迁过程或光谱研究方法有吸收光谱、光电流谱、光荧光和荧光激发谱、调制光谱以及喇曼散射光谱。关于亚带能量状态将着重讨论量子阱中的激子效应和价带亚带混和及其对带间光跃迁的影响。 相似文献
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通过预平衡核反应理论中的激子模型理论 ,给出了激子模型中的激子态寿命和激子态发射率与跃迁率的表达式。并通过计算给出了轻核 (9Be、1 6O) ,中等核 (56Fe、64Zn) ,重核 (1 75Lu、1 84W)等核的各激子态寿命以及它们的发射率和跃迁率。结果表明对于轻核 ,前几个激子态在反应中占主要的部分 ,使用时可以作无返回近似。这反映了在轻核反应中 ,预平衡反应占主要的地位。 相似文献
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在有效质量近似下,考虑内建电场效应,采用变分法详细研究了受限于纤锌矿Mg_xZn_(1-x)O/ZnO/Mg_xZn_(1-x)O圆柱形应变量子点中离子受主束缚激子(A~-,X)的带间光跃迁吸收系数随量子点尺寸、Mg含量和离子受主杂质中心位置的变化情况,并和离子施主束缚激子(D~+,X)及自由激子进行了比较.结果表明:随着量子点尺寸的减小,(A~-,X)的光跃迁吸收强度增强,吸收曲线向高能方向移动,出现蓝移现象.随着Mg含量增加,(A~-,X)的光跃迁吸收曲线蓝移,且吸收强度减弱.随着离子受主杂质从量子点的左界面沿材料生长方向移至量子点的右界面,光跃迁吸收曲线向低能方向移动,出现红移现象.此外,与离子施主束缚激子(D~+,X)相比,随着沿材料生长方向掺入杂质位置的变化,光跃迁吸收曲线移动的方向相反.但不管是掺入离子受主杂质还是离子施主杂质,当离子杂质从量子点的左异质界面沿材料生长方向移至右异质界面时,光跃迁吸收峰的移动量大致相同. 相似文献
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透射电子显微镜(TEM)研究了CdS0.3,Se0.7掺杂的半导体微晶玻璃的微晶尺寸分布,微晶尺寸由热处理温度和时间来控制。当微晶尺寸接近或小于激子Bohr半径时,吸收光谱出现亚带结构,带隙能向高能移动,证明了量子尺寸效应。非相干光时间延迟的四波混频(TDFWM-IL)技术测试研究了玻璃的快速弛豫过程。 相似文献
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利用差示扫描量热法(DSC)研究了1,2-丙二醇在不同降温速率下的协同松弛行为,以曲线拟合方法获得非线性Adam-Gibbs焓松弛参数.结果表明,模型参数强烈依赖于降温速率.在较高降温速率下获得的模型参数和用比热频谱及介电方法得到的结果很接近.利用DSC测得的比热容数据和拟合结果估算了1,2-丙二醇体系非线性AG理论的两个主要微观参数,即协同重排域(CRR)尺寸z*和对应的位形态数量W*.结果表明,如果采用聚合物玻璃推荐的W*,则会导致1,2-丙二醇在玻璃化温度处的CRR中的分子数小于1.而如果采用Johari的方法,则可得到玻璃化温度处的CRR中约有3个1,2-丙二醇分子,但随之产生的W*却异常的大.利用Donth的热力学温度波动公式估算得到的1,2-丙二醇在玻璃化温度处的CRR中的分子数为355,这和Johari方法得到结果难以统一.表明对于小分子氢键液体而言,非线性AG理论中z*的物理意义应重新审视. 相似文献
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Assuming that the Raman gain profile of silica fiber is a triangular function, we derive analytic solutions of N-channel steady-state forward SRS coupling wave equation with equal (but arbitrary) channel spacing. Considering the SRS cross coupling among N-channels, the analytic solutions are applicable to arbitrary signal light power. The results point out that the sequence mi=pi(z)/pi(0) [pi(z) and pi(0) is the power of signal light of i-th channel at transmission length z and 0, respectively. i=1,2,...N] maintains a geometric progression with the common ratio q in the transmission process. The common ratio q varies as a exponential function of the effective transmission length, the sum of input light power and the channel spacing, respectively. 相似文献
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1 Introduction StimulatedRamanscattering(SRS)isanimportantnonlinearprocess.WiththeaidoftheSRS,wecanturnopticalfibersintobroadb?.. 相似文献
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A particle in a random potential with logarithmic correlations in dimensions d = 1,2 is shown to undergo a dynamical transition at T(dyn)>0. In d = 1 exact results show T(dyn) = T(c), the static glass transition temperature, and that the dynamical exponent changes from z(T) = 2+2(T(c)/T)(2) at high T to z(T) = 4T(c)/T in the glass phase. The same formulas are argued to hold in d = 2. Dynamical freezing is also predicted in the 2D random gauge XY model and related systems. In d = 1 a mapping between dynamics and statics is unveiled and freezing involves barriers as well as valleys. Anomalous scaling occurs in the creep dynamics, relevant to dislocation motion experiments. 相似文献
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喷雾蒸发燃烧的研究对指导发动机燃烧系统设计具有重要意义。本文搭建了高速数字全息系统,在线测量乙醇喷雾火焰中液滴的粒径、三维位置、速度及蒸发率。对喷雾火焰中的液滴进行了统计分析,得到液滴粒径及三维空间分布。燃烧喷雾场液滴的平均粒径为68μm;非燃烧火焰测试区液滴数量多且较密集,燃烧火焰测试区液滴数量少且稀疏.追踪单液滴并处理得到湍流火焰中液滴的运动轨迹及速度。通过研究粒径的平方D2随停留时间ts的变化,测得液滴平均蒸发率为-3.343×10-7 m2/s. 相似文献
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Aggregation kinetics and cluster-size distributions are studied with off-lattice, diffusion-limited cluster-cluster simulations. With increased cluster crowding (occurring at late times) as measured by the normalized free volume, Omega, both the kinetics speeds up and the size distribution broadens. The exponents characterizing each, z and lambda, respectively, are found to be universal functions of Omega. Moreover, the relation z=(1-lambda)(-1) continues to hold up to omega=0 (the ideal gel point), implying mean-field kinetics still applies despite the crowding. 相似文献
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The I-V characteristics of a Josephson junction shunted by an Ohmic resistor shows sharp peaks when levels in neighbouring wells are crossing. We consider the shape and size of these peaks using a double-well model where the wells are given in parabolic approximation. The friction of arbitrary strength is included by the help of a bath of infinitely many degrees of freedom. 74.50.+z. 相似文献
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We study a zero range process on scale-free networks in order to investigate how network structure influences particle dynamics. The zero range process is defined with the rate p(n) = n(delta) at which particles hop out of nodes with n particles. We show analytically that a complete condensation occurs when delta < or = delta(c) triple bond 1/(gamma-1) where gamma is the degree distribution exponent of the underlying networks. In the complete condensation, those nodes whose degree is higher than a threshold are occupied by macroscopic numbers of particles, while the other nodes are occupied by negligible numbers of particles. We also show numerically that the relaxation time follows a power-law scaling tau approximately L(z) with the network size L and a dynamic exponent z in the condensed phase. 相似文献