PbWO4晶体中铅空位相关的色心模型

使用密度泛函缀加平面波法,按照能量最低原理采用共轭梯度方法对几种含铅空位和不含铅空位的钨酸铅晶体进行结构优化处理,计算了铅空位周围晶格的弛豫,得到铅空位周围的晶格结构,同时对计算结果进行了讨论;在得到几何优化结构的基础上,利用相对论性密度泛函离散变分法进一步计算了几种钨酸铅晶体结构的电子态密度.计算结果表明:1)铅空位周围的晶格驰豫的结果使铅空位的局部电负性减弱.2)Pb 6s态的能级位于离价带顶10eV左右,说明Pb 6s态上的电子很难再失去,所以在钨酸铅中不太可能存在Pb3+或Pb4+.3)价带顶主要由O的2p态占居,氧的2p态最容易失去电子.4)铅空位周围的可能形成的色心是VF--VK+缔合色心.     

钨酸铅晶体中与铅空位有关的电子结构和色心模型研究

根据密度泛函理论对钨酸铅晶体中铅空位周围的晶格进行了结构优化，计算得到铅空位周围的晶格结构、电子态密度分布和偏振吸收光谱；计算结果表明钨酸铅晶体中铅空位的两价负电性是通过铅空位周围的氧共同抓获两个空穴来维持局部电中性的，即铅空位周围形成的色心模型为［O₂^3--V_Pb^2--O₂^3-］，不同的氧离子抓获空穴方式不同形成不同的色心，对应不同的吸收带；根据吸收带的偏振性质，提出了各个 关键词： 钨酸铅晶体 色心模型 电子结构 偏振特性     

类氖钛软X射线激光空间发射区域研究

使用高分辨平焦场谱仪，在“星光”激光器上，对类氖钛J=0—1，3p—3s跃迁32.6nm软X射线激光空间发射区域进行了实验测量，并与LASNEX和XRASER程序模拟结果作了比较．实验采用预脉冲打靶技术，预、主脉冲时间间隔5ns，峰值能量比为1%．结果表明：当驱动能量在50—150J范围内变化时，等离子体介质中X射线激光发射区与驱动能量大小密切相关，并随之增大而增大 关键词：     

Quantum electrodynamics in a laser and the electron laser collisionQuantum electrodynamics in a laser and the electron laser collision

Quantum electrodynamics in a laser is formulated, in which the electron-laser interaction is exactly considered, while the interaction of an electron and a single photon is considered by perturbation. The formulation is applied to the electron- laser collisions. The effect of coherence between photons in the laser is therefore fully considered in these collisions. The possibility of y-ray laser generation by use of this kind of collision is discussed.     

First Principles Study on Electronic Structures of Mn^2＋：CdMoO4 Crystals

Electronic structures of the Mn^2＋ ：CdMoO4 crystal axe studied within the framework of the fully relativistic self-consistent Dirac Slater theory, using a numerically discrete variation （DV-Xα） method. The calculated results indicate that the 3d states of Mn have donor energy level in the forbidden band of CdMoO4 crystal. The O^2- transition energy of O 2p→Mn 3d is 3.12eV under excitation corresponding electronic transition being O^2-＋Mn^2＋→↑hvex=3.12 eV O^-- ＋Mn^＋→↑hvem O^2-＋Mn^2＋. It is predicted that the wavelength of emission should be located in the range of the 500-600nm. Thus the 500-600mm emission bands peaking at 550nm （2.25eV） of CdMoO4 crystal under excitation may be related to the Mn-like dopant ion in CdMoO4 crystal.     

手征对称性的部分恢复与核物质中的π凝聚

由π凝聚的相对性半经典理论推知:由于σ模型中魔圆半径随核密度变化,核物质中可以发生π凝聚。算得的临界密度略高于正常基态核物质密度。     

氢键质子的运动与胞嘧啶的变异几率

运用Gaussian98 MP2/6 311G(d， p)级的从头计算法计算了DNA分子中胞嘧啶碱基中H13质子的势能曲面。 发现有两个势阱: 其中一个对应正常的胞嘧啶， 而另一个则对应它的顺式亚胺式互变异构体。 质子在这两个势阱的束缚对热扰动是稳定的。 质子在势阱中像单摆一样绕着离它最近的氮原子摆动， 还可以远离氮原子与其它碱基形成氢键。 估算出的H13质子从一个势阱到另一个势阱的穿透几率表明质子呆在其中一个势阱中的寿命大约是6×102 a， 这使胞嘧啶和它的顺式亚胺式互变异构体在室温气相实验中远不能达到热平衡。 对这些结果的生物学意义作了讨论。 The potential energy surface of the H13 proton in base cytosine of theDNA molecules is calculated ab initio at the Gaussian98 MP2/6 311G(d， p) level. Two potential wells are found. One corre sponds to the normal cytosine， while the other corresponds to its imino tautomer. The bindings of the proton in these wells are stable enough against the thermo disturbance. The motions of the proton in these wells are oscillations around the nearest nitrogen atom like the pendulum， and may move far away from the nitrogen atom to form the hydrogen bond with other bases. The estimated tunneling probability of the H13 proton from one well to another well shows that the life time of the proton staying in one of these wells is about 6×102 a. It is too long to let tautomers of cytosine be in thermodynamical equilibrium in a room temperature gas phase experiment. The biological significance of these results is discussed.     

PbWO4晶体中的填隙氧及其对晶体光学性质的影响

运用GULP计算软件模拟计算了PbWO₄(PWO)晶体中不同位置的填隙氧原子点缺陷的生成能，计算结果表明：当填隙氧原子存在于(WO₄)^2-的周围时，填隙氧原子点缺陷的生成能最低；进一步运用基于密度泛函理论的全数值自洽DV-Xα方法计算了包含填隙氧原子的PWO晶体的态密度，计算结果表明：当填隙氧处在(WO₄)^2-的周围时，容易与(WO₄)^2-上的一个或两个氧离子相互作用形成分子离子O₂^2-或O₃^4-，通过分析这些计算结果，认为PWO晶体中350 nm吸收带的出现很可能与晶体中的氧分子离子有关.     

First-Principles Studies on Electronic Structures and Absorption Spectra of PbWO4 Crystals with Defect [V^2- Pb-V^2＋ o-V^2- Pb]^2-c

Electronic structures and absorption spectra for perfect PbW04 （PWO） crystals and the crystal containing aggregated defect [V^2- Pb-V^2＋ o-V^2- Pb]^2-have been calculated using density functional theory code CASTEP with the lattice structure optimized. The calculated absorption spectra of the PWO crystal containing the aggregated defect [V^2- Pb-V^2＋ o-V^2- Pb]^2-exhibit two absorption bands peaking at 1.90eV （65Onto） and 3.02eV （41Onto）. It is predicted that the 420 and fiSOnm absorption bands are related to the existence of the aggregated defect [V^2- Pb-V^2＋ o-V^2- Pb]^2-in the PWO crystal.     

软X射线多层膜反射镜反射率测量

 采用线状激光等离子体作为软X光源,用具有空间分辨的掠入射光栅谱仪对正入射多层膜反射镜进行了反射率测量。谱仪测谱范围20~40nm,谱分辨0.05nm,测得50层C/Al反射镜在中心波长28.6nm处反射率为22%,带宽约为2.5nm。