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1.
《光子学报》2015,(1)
在有效质量近似下,计算了盘形量子点中离子施主束缚激子的结合能、光跃迁能、振子强度及辐射寿命.设盘形量子点由有限长的柱形ZnO材料组成,四周被MgxZn1-xO包围,离子施主局域在盘轴.考虑了由于自发极化和压电极化引起的内建电场效应,并在有限深约束势下采用合适的变分波函数进行.计算结果表明,量子盘结构参数(盘高度及垒中Mg组分)和离子施主的位置对离子施主束缚激子的结合能、光跃迁能、振子强度及辐射寿命有强烈的影响.随着盘高度的增加,结合能、光跃迁能和振子强度减小,而辐射寿命增加.对含Mg量较高的盘形量子点,盘高度对结合能、光跃迁能、振子强度及辐射寿命的影响更显著.当施主杂质位于量子点的左界面附近时结合能(光跃迁能)有极大(极小)值,而当施主杂质位于量子点的右界面附近时结合能(光跃迁能)有极小(极大)值. 相似文献
2.
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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考虑应变,在有效质量、有限高势垒近似下,变分研究了纤锌矿GaN/AlxGa1 -xN柱形量子点中类氢施主杂质态结合能随流体静压力、杂质位置及量子点结构参数(量子点高度、半径、Al含量)的变化关系.结果表明,类氢施主杂质态结合能随流体静压力增大而增大,且在量子点尺寸较小时,流体静压力对杂质态结合能的影响更为显著.受流体静压力的影响,杂质态结合能随量子点高度、半径的增加而单调减少,且变化趋势加剧;随Al含量增加而增大的趋势变缓.无论是否施加流体静压力,随着类氢施主杂质从量子点左界面沿材料生长方向移至右界面,杂质态结合能在量子点的右半部分存在一极大值.流体静压力使得极大值点向量子点中心偏移. 相似文献
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在有效质量近似下,用变分法研究了闪锌矿GaN/AlxGa1-xN单量子点中的类氢杂质态。结果表明量子点中的杂质位置和量子点结构参数(量子点高度H、半径R及Al含量x)对施主束缚能有很大的影响。当杂质位于量子点中心时,施主束缚能 有最大值。此外,施主束缚能 随着量子点高度H(半径 )的增大而减小,随着量子点中Al含量x的增大而增大。 相似文献
8.
考虑应变,在有效质量、有限高势垒近似下,变分研究了纤锌矿GaN/AlxGa1-xN柱形量子点中类氢施主杂质态结合能随流体静压力、杂质位置及量子点结构参数(量子点高度、半径、Al含量)的变化关系.结果表明,类氢施主杂质态结合能随流体静压力增大而增大,且在量子点尺寸较小时,流体静压力对杂质态结合能的影响更为显著.受流体静压力的影响,杂质态结合能随量子点高度、半径的增加而单调减少,且变化趋势加剧;随Al含量增加而增大的趋势变缓.无论是否施加流体静压力,随着类氢施主杂质从量子点左界面沿材料生长方向移至右界面,杂质态结合能在量子点的右半部分存在一极大值.流体静压力使得极大值点向量子点中心偏移. 相似文献
9.
在一维等效模型下采用有效差分法对抛物型量子阱线中带电激子的束缚能进行了计算,分析了约束势以及磁场对带电激子束缚能的影响,并对带正电激子(X+)和带负电激子(X-)的情况进行了比较.结果表明:电子和空穴的振子强度对带电激子的稳定性有重要影响,X+的束缚能不总是比X-的大,随着空穴振子强度的增加束缚能的函数曲线将会出现交叉,这同实验得到的结果符合;磁场的存在会增加粒子间的束缚,并且磁场对束缚能的影响同振子强度大小有关.
关键词:
带电激子
量子线
束缚能
磁场 相似文献
10.
考虑应变,在有效质量、有限高势垒近似下,变分研究了纤锌矿GaN/AlxGa1-xN柱形量子点中类氢施主杂质态结合能随流体静压力、杂质位置及量子点结构参数(量子点高度、半径、Al含量)的变化关系.结果表明,类氢施主杂质态结合能随流体静压力增大而增大,且在量子点尺寸较小时,流体静压力对杂质态结合能的影响更为显著.受流体静压力的影响,杂质态结合能随量子点高度、半径的增加而单调减少,且变化趋势加剧;随A1含量增加而增大的趋势变缓.无论是否施加流体静压力,随着类氢施主杂质从量子点左界面沿材料生长方向移至右界面,杂质态结合能在量子点的右半部分存在一极大值.流体静压力使得极大值点向量子点中心偏移. 相似文献
11.
null 《中国物理C(英文版)》2017,41(5):054102-054102
A systematic dependence of shape fluctuation energy product SFE * B(E2)↑ and rotational energy product ROTE * B(E2)↑ on the valence nucleon product Np Nn is carried out in the Z = 50-82,N = 82-126 major shell space.For the shape transitional nuclei,the product SFE*B(E2)↑ drops to zero and becomes negative,indicating direct dependence on N_pN_n.A relative rise,on the other hand,is observed in the product ROTE*B(E2) ↑plotted against N_pN_n for all the nuclei in Z = 50-82 and N = 82-126.In the N 104 region,large positive values of the product SFE * B(E2) ↑ are observed for the Pt nucleus,which indicates sphericity.A systematic study of the product SFE * B(E2)↑ and ROTE * B(E2) ↑ with atomic number Z is also discussed.The products SFE * B(E2) ↑and ROTE * B(E2) ↑ vary sharply with Z for the N = 88 isotones.We discuss here for the first time the correlation between SFE * B(E2) ↑ and ROTE * B(E2) ↑ with valence nucleon product N_pN_n. 相似文献
12.
Spin--orbit ab initio curves of 80Se2+ ion and theassignment of photoelectron spectra of 80Se2 molecule 下载免费PDF全文
This paper carries out ab initio calculations to study the ^80Se2(X^3Σg^-) state and ^80Se2^+(X^2Πg), ^80Se2^+(a^4Πg) states by using completed active space self-consistent field and multi-reference second order perturbation theory. The electronic curves of these states including spin-orbit coupling are calculated, and then the spectroscopic parameters are obtained. The photoelectron spectra of ^80Se2 molecule in gas phase are assigned according to Franck-Condon analysis based on calculated potential energy curves. The ionization energies of ^80Se2 molecule are determined by the present calculation. 相似文献
13.
Ab initio calculation of accurate dissociation energy, potential energy curve and dipole moment function for the A1∑ + state 7LiH molecule 下载免费PDF全文
The reasonable dissociation limit of the A1∑+ state
$^{7}$LiH molecule is obtained. The accurate dissociation energy and the
equilibrium geometry of this state are calculated using a
symmetry-adapted-cluster configuration-interaction method in complete active space
for the first time. The whole potential energy curve and the dipole moment
function for theA1∑+ state are calculated over a wide
internuclear separation range from about 0.1 to 1.4\,nm. The calculated
equilibrium geometry and dissociation energy of this potential energy curve
are of R_{\e}=0.2487\,nm and D_{\e}=1.064\,eV, respectively. The unusual negative
values of the anharmonicity constant and the vibration-rotational coupling
constant are of \textit{\omega }_{\e}\textit{\chi
}_{\e}=--4.7158cm^{ - 1} and \textit{\alpha
}_{\e}=--0.08649cm^{ -1}, respectively. The vertical excitation
energy from the ground to the
A1∑+ state is calculated and the value is of 3.613\,eV at
0.15875nm (the equilibrium position of the ground state). The highly
anomalous shape of this potential energy curve, which is exceptionally flat
over a wide radial range around the equilibrium position, is discussed in
detail. The harmonic frequency value of 502.47cm1 about this state
is approximately estimated. Careful comparison of the theoretical
determinations with those obtained by previous theories about the
A1∑+ state dissociation energy clearly shows that the present
calculations are much closer to the experiments than previous theories, thus
represents an improvement. 相似文献
14.
Amanpreet Kaur Sandhu Surinder Singh Om Prakash Pandey 《Indian Journal of Physics》2009,83(7):985-991
Silica based glasses are used as nuclear shielding materials. The effect of radiation on these glasses varies as per the constituents
used in these glasses. Glasses of different composition of SiO2-Na2OMgO-Al2O3 were made by melt casting techniques. These glasses were irradiated with neutrons of different fluences. Optical absorption
measurements of neutron-irradiated silica based glasses were performed at room temperature (RT) to detect and characterize
the induced radiation damage in these materials. The absorption band found for neutron-irradiated glasses are induced by hole
type color centers related to non-bridging oxygen ions (NBO) located in different surroundings of glass matrix. Decrease in
the transmittance indicates the formation of color-center defects. Values for band gap energy and the width of the energy
tail above the mobility gap have been measured before and after irradiation. The band gap energy has been found to decrease
with increasing fluence while the Urbach energy shows an increase. The effects of the composition of the glasses on these
parameters have been discussed in detail in this paper.
相似文献
15.
采用从头计算的多参考组态相互作用方法和含扩散基的3个基组aug-cc-PVXZ (X=D,T,Q) 计算了SO和ClO分子及其分子离子的势能曲线,确定了平衡几何结构、离解能,并采用Feller拟合递推方法得到了基函数为无穷大计算水平值. 确定了SO-,ClO+,ClO-分子离子的基态. 通过Murrell-Sorbie势能函数和最小二乘法拟合得到了解析势能函数. 基于所得的势能函数,通过解核运动的薛定谔方程得到振
关键词:
多参考组态相互作用
势能曲线
解析势能函数
光谱常数 相似文献
16.
Within the framework of effective-mass approximation, the binding energy of a hydrogenic donor impurity in zinc-blende (ZB) InxGa1−x N/GaN cylindrical quantum well wires (CQWWs) is investigated using variational procedures. Numerical results show that the ground-state donor binding energy Eb is highly dependent on the impurity position and the CQWWs structure parameters. The donor binding energy for a shallow donor impurity located at the center of the CQWWs is the largest. As the impurity position changes from the center of the wire to its edge, the donor binding energy gets smaller. Also, we have found that In concentration is a very important value to tailor the system, since the binding energies close to binding energy maxima are strongly dependent on In content. 相似文献
17.
T. Shalapska G. Stryganyuka D. Trotsc T. Demkiv A. Gektin A. Voloshinovskii P. Dorenbos 《Journal of luminescence》2010,130(10):1941-1945
LiPr1−xCexP4O12 (x=0, 0.002, 0.02; 0.1) powder samples were prepared using the melt solution technique. Luminescent parameters of LiPr1−xCexP4O12 phosphors have been investigated under ultraviolet-vacuum ultraviolet (3-12 eV) synchrotron radiation and X-rays excitation at room and near liquid He temperatures. Excitation luminescence spectra of Ce3+ emission, luminescent spectra and decay curves from the lower excited state levels of the 4f15d1 and 5d1 electronic configuration of the Pr3+ and Ce3+, respectively, clearly indicate energy transfer from Pr3+ to Ce3+. Energy migration proceeds via the Pr-sublattice followed by nonradiation transfer from Pr3+ to Ce3+ ions. 相似文献
18.
Comparative analysis of energy-level splitting of Pr3+ doped in LiYF4 and LiBiF4 crystals: a complete energy matrix calculation 下载免费PDF全文
Based on the combination of Racah's group-theoretical consideration with Slater's wavefunction, a 91 × 91 complete energy matrix is established in tetragonal ligand field D2d for Pr3+ ion. Thus, the Stark energy-levels of Pr3+ ions doped separately in LiYF4 and LiBiF4 crystals are calculated, and our calculations imply that the complete energy matrix method can be used as an effective tool to calculate the energy-levels of the systems doped by rare earth ions. Besides, the influence of Pr3+ on energy-level splitting is investigated, and the similarities and the differences between the two doped crystals are demonstrated in detail by comparing their several pairs of curves and crystal field strength quantities. We see that the energy splitting patterns are similar and the crystal field interaction of LiYF4:Pr3+ is stronger than that of LiBiF4:Pr3+. 相似文献
19.
采用高温固相法制备了Ca4-xY5.95 (SiO4)6F2:0.05Ce3+, xMn2 +系列荧光粉,并对其发光性质以及Ce3+, Mn2 +在Ca4Y6 (SiO4)6F2 (CYSF)基质中的能量传递过程进行了研究.相结构研究表明: CYSF属于一种基于磷灰石结构的类质同象化合物.CYSF: 0.05Ce3+, xMn2+荧光粉在200–373 nm为宽带激发光谱,Ce3+和Mn2+在408 nm和602 nm的发射峰分别由Ce3+的5d→4f的跃迁和Mn2+的4T1 (4G)→ 6A1 (6S)的跃迁产生.光谱重叠现象以及荧光寿命测试结果证明了Ce3+对Mn2+具有敏化作用,能级结构分析进一步证实该体系中存在Ce3+→Mn2+的能量传递过程,可有效地将Ce3+的蓝光转换为红橙光.
关键词:
磷灰石
发光性质
能量传递 相似文献
20.
We have measured the resistivity of textured Bi1.84Pb0.4Sr2Ca2Cu3Oy silver-clamped thick films as a function of temperature, current density ranging from 10 to 1×103 A/cm2 and magnetic field up to 0.3 T. We find that the effective activation energy Ue follows Ue(T,J,H)=U0(1−T/Tp)mln(Jc0/J)H− with m=1.75 for Hab-plane and 2.5 for Hc-axis and =0.76 for Hab and 0.97 for Hc, for the current density regime above 100 A/cm2, where Tp is a function of applied magnetic field and current density. This result suggests the effective activation energy Ue be correlated with the temperature, current density and magnetic field. The possible dissipative mechanisms responsible for the temperature, current density and magnetic field dependence of the effective activation energy are discussed. 相似文献