q变形对相干态的相位概率分布特性

通过推广Pegg和Barnett的相位算符和相位态到q变形的双模情况, 应用数值计算 研究了q变形对相干态的相位概率分布特性. 结果表明, q变形对相干态的相位概率分布受到相位参数、q参数和参数│ξ│的调节, 从而反映出不同的量子相干特性.     

纳米晶Y_2SiO_5∶Eu的浓度猝灭研究

报道了分别用溶胶－凝胶法合成的Ｙ２ＳｉＯ５∶Ｅｕ纳米晶和用高温固相法合成常规尺度的Ｙ２ＳｉＯ５∶Ｅｕ材料的光致发光光谱和猝灭浓度的实验研究．结果表明：纳米Ｙ２－ｘＥｕｘＳｉＯ５比常规尺度的Ｙ２－ｘＥｕｘＳｉＯ５有更高的猝灭浓度和更高的发光亮度．理论分析认为这是由于在纳米材料中能量共振传递被阻断和猝灭中心在各个纳米晶内分布的涨落造成的．这个结果为高亮度的Ｙ２ＳｉＯ５∶Ｅｕ纳米材料的实际开发应用展示了广阔前景．     

囚禁离子的非线性Jaynes-Cummings模型及其布居数反转演化

从描述囚禁离子与驻波激光场相互作用的Jaynes-Cummings(J-C)模型出发，导出了囚禁离子谐振动单量子共振激发相互作用的非线性J-C模型. 通过求解这一模型的系统状态随时间变化，数值研究了离子布居数反转的演化规律. 结果表明，离子布居数反转演化的崩塌-复原周期与Lamb-Dick参数η和离子在驻波激光场中的位置有关，随着η参数的增大，离子布居数反转的崩塌-复原周期变短，当离子质心的位置从驻波激光场的波节移向波腹时，离子布居数崩塌-复原的周期变长. 关键词： 驻波激光场 囚禁离子 非线性J-C模型 Lamb-Dick参数     

4fN-15d energy levels of lanthanides: aquasi-angular-momentum approach and its application to Cs2NaYF6:Er3+

<正>The spin-orbit interaction of the 5d electron needs to be taken into account to give the proper energy structure for the 4f^N-15d configuration of heavy lanthanide ions occupying a site with ligands forming an octahedron.This paper derives theoretical results for the energy structure by treating the t₂ orbitals as quasi p orbitals and then using angular-momentum coupling techniques.An analytic expression for the electric dipole absorption line strengths between 4f^N multiplets and 4f^N-15d states is given in terms of various angular-momentum quantum numbers and re-coupling coefficients.The result is then applied to interpret the excitation spectrum of Cs₂NaYF₆:Er³⁺.The high-spin and low-spin states of Cs₂NaYF₆:Er³⁺ are discussed in terms of the wavefunctions obtained by using the developed theoretical model.     

稀土离子激活发光材料中能级跃迁的选择定则

能级跃迁的选择定则可用于判别含稀土离子的发光材料中的光吸收、能量传递和发光及非辐射能量弛豫过程是否发生.本研究中,我们根据跃迁所涉及到的电子组态、稀土离子所处格位的对称性、跃迁所涉及到的多重态及晶格振动情况进行了细致地讨论分析.对于光吸收和发射过程,我们得到了和相关文献报道一致的结果,并对有些结果进行了更细致的解释.对...     

纳米晶体ZnS∶Mn~(2 )发光寿命异常减缩机理的探讨

纳米晶体ＺｎＳ∶Ｍｎ２＋中Ｍｎ２＋粒子４Ｔ１→６Ａ１的发光寿命比晶体减缩了５个量级，这颇令人费解，因为通常解除自旋禁戒的磁作用远无如此强的效应．假定基质态的自旋不为零，且考虑了Ｍｎ２＋的ｄ电子和基质之间的交换库仑作用．若基质存在比Ｍｎ２＋的４Ｔ１激发态能量略高的某种激发态，则这种交换库仑作用将导致这两种激发态之间的混合，从而可解除发光能级弛豫中的自旋禁戒．这种混合随基质颗粒尺寸的减小而加强．我们并对此机制进行粗略的数值估计，给出了和实验相容的结果．     

First-principles study of the local structure and crystal field of Yb2＋ in sodium and potassium halides

The local coordination structures around the doping Yb 2+ ions in sodium and potassium halides were calculated by using the first-principles supercell model.Both the cases with and without the charge compensation vacancy in the local environment of the doping Yb 2+ were calculated to study the effect of the doping on the local coordination structures of Yb 2+.Using the calculated local structures,we obtained the crystal-field parameters for the Yb 2+ ions doped in sodium and potassium halides by a method based on the combination of the quantum-chemical calculations and the effective Hamiltonian method.The calculated crystal-field parameters were analyzed and compared with the fitted results.     

First-principles study of the local structure and crystal field of Yb2+ in sodium and potassium halides

The local coordination structures around the doping Yb²⁺ ions in sodium and potassium halides were calculated by using the first-principles supercell model. Both the cases with and without the charge compensation vacancy in the local environment of the doping Yb²⁺ were calculated to study the effect of the doping on the local coordination structures of Yb²⁺. Using the calculated local structures, we obtained the crystal-field parameters for the Yb²⁺ ions doped in sodium and potassium halides by a method based on the combination of the quantum-chemical calculations and the effective Hamiltonian method. The calculated crystal-field parameters were analyzed and compared with the fitted results.     

分析指认固体中稀土离子4f-5d跃迁光谱的简单模型

概要介绍和总结最近由段昌奎等人提出,并经发展扩充的用以分析指认固体中稀土离子f-d跃迁光谱的简单模型,以及对Nd³⁺、Sm³⁺、Eu³⁺、Eu²⁺、Tb³⁺、Ho³⁺、Er³⁺的f-d激发光谱及Nd³⁺的d-f辐射谱的成功应用。也论及值得进一步研究的其他离子的f-d谱。     

Ca3Sc2Si3O12:Ce3+的第一性原理研究

对Ca₃Sc₂Si₃O₁₂:Ce³⁺共掺杂N^3-、Sc³⁺、Mn²⁺、Mg²⁺和Na⁺进行第一性原理计算,研究不同的电荷补偿对发光中心Ce³⁺的影响．首先利用密度泛函理论构建超晶胞模型对Ce³⁺周围的局部结构进行了优化,然后通过CASSCF/CASPT2 RASSI-SO计算得到Ce³⁺的4f→5d跃迁能量．计算数据与实验光谱相吻合．实验光谱中的一个未知峰值理论分析确认是Sc³⁺替代Si⁴⁺导致的．