BeF2分子基态势能函数研究

利用密度泛函理论（DFT）B3LYP/aug-cc-PVTZ方法对BeF和BeF2分子进行计算, BeF分子的基态电子态为X2Σ+,平衡核间距Re=0.1367 nm,BeF2分子最稳定构型为D∞h构型,基态电子态为X1Σg+,离解能De=13.4 eV。利用最小二乘法拟合了BeF分子基态的Murrell-Sorbie势能函数,并得到其光谱数据与力常数。结合全局多体项展式方法,导出了基态BeF2分子基态势能函数的解析表达式,该函数准确反映了BeF2分子的结构以及静态反应特征,这些结果为进一步探索BeF2的微观分子反应动力学提供了基础。     

稀土三氟醋酸盐晶体的光谱特性

本文合成了系列稀土三氟醋酸盐晶体[Re(CF3COO)3·3H2O](Re=Eu,Gd,Tb,Dy)和[TbxY1-x(CF3COO)3·3H2O]2(x=0.05,0.10,0.15,0.20,0.25mol),测定其晶体结构属单斜晶系,空间群为P21/c;较详细地讨论了Eu3+,Gd3+,Tb3+,Dy3+在这些化学计量化合物中的光谱特性,以及在[TbxY1-x(CF5COO)3·3H2O]中Tb3+的发光强度随其浓度的变化规律。     

ZBLAN玻璃中Nd~(3+),Tm~(3+),Yb~(3+)的上转换发光特性

采用高温固相法制备了Nd,Tm和Yb掺杂的ZBLAN玻璃上转换材料.Tm3+,Yb3+的摩尔浓度分别固定为0.01%,0.3%,Nd3+摩尔浓度变化范围为0.1%～2%.在室温下,测试了样品在300～1 000nm间的吸收光谱.在798 nm近红外光激发下,测试了样品的上转换光谱.实验发现,样品在798 nm红外光激发下发出了较强的多波段(红,蓝和绿)的可见光.由上转换可见光各波段的发射谱线,给出了能级跃迁机制.蓝光主要来源于Tm3+的激发态1G4到基态3H6的跃迁,绿光来源于Nd3+的2H7/2到基态4I9/2的跃迁,红光来源于Nd3+的2H11/2到基态4i9/2的跃迁.研究发现,在Nd3+,Tm3+,Yb3+:ZBLAN玻璃样品中存在激发态吸收,能最转移和交叉弛豫等上转换过程.其发光机理是Nd3+,TM3+和Yb3+离子之间的能量转移.根据Nd3+摩尔浓度不同其上转换发光强度不同,分析了掺入稀土的浓度对上转换发光效率的影响.当Nd3+浓度为1.5%(摩尔分数)时上转换发光最强,大于1.5%后发光开始减弱.     

PuN基态和低激发态的分子结构与相对论有效原子实势

用Pu的三种不同相对论有效原子实势 (RECP)和密度泛函(B3LYP)方法对PuN基态和低激发态(4Σ+、6Σ+、8Σ+、10Σ+)的分子结构进行了计算,得到了相应的平衡几何构型和谐振频率.采用最小二乘法拟合得到了PuN分子的Murell-sorbie势能函数,在此基础上推导出完整的力常数和光谱数据,并与实验值作对比.结果表明:PuN的基态为X6Σ+,其余为低激发态;在三种RECP中,对于ωe的计算,60个中心电子的SDDRECP/B3LYP给出的结果与实验值符合得比较好(如X6Σ+:ωe=840.77 cm-1,ωeχe=5.73·"cm-1,De=5.880 6 eV,Re=0.176 3 nm,Be=0.408 4 cm-1,αe=3.3E-03 cm-1).计算还给出了相应的电荷布居、自旋密度、电偶极矩和能量特征等系列分子的性质.     

室温下Yb3+和Er3+掺杂的NaYS2粉末材料的Stocks和Anti-Stocks发光

合成了NaYS2:0.20Yb3+,0.03Er3+和NaYS2:0.03Er3+粉末材料,通过材料的Stocks和Anti-Stocks光谱,研究了Er3+和Yb3+跃迁几率对激发方式的依赖特征,以及局域环境对S2-Re3+(Re3+=Yb3+或Er3+)电荷迁移态的影响,探讨了在共掺杂和单掺杂状态下Yb3+和Er3+间的能量传递和Er3+的Stocks和Anti-Stocks辐射跃迁机制。     

用MRCI方法研究CS+同位素离子X2Σ+和A2∏态的光谱常数与分子常数

利用内收缩多参考组态相互作用方法和价态范围内的最大相关一致基aug-cc-pV6Z,在0.05-0.60 nm的核间距范围内计算了CS+离子X2Σ+和A2∏态的势能曲线.利用CS+离子的势能曲线并在同位素质量修正的基础上,拟合出了X2Σ+和A2∏态的同位素离子12C32S+,12C34S+和12C33S+等的光谱常数.对于X2Σ+态的主要同位素离子12C32S+,其光谱常数D0,De,Re,ωe,ωeχe,αe,和Be分别为6.4694,6.5542 eV,0.14975 nm,1371.89,7.5746,0.006481和0.8616 cm-1;对于A2∏态的主要同位素离子12C32S+其D0,De,Re,ωe,ωxχe,αe和Be分别为4.8460 eV,4.9084 eV,0.16449 nm,l009.31和6.4970 cm-1,0.006110和O.7134 cm-1.这些数据与已有的实验结果均符合很好.通过求解核运动的径向薛定谔方程,找到了J=0时CS+(X2Σ+)的全部68个振动态、CS+(A2∏)的全部80个振动态.对于每一振动态,还分别计算了它的振动能级、经典转折点、转动惯量及离心畸变常数,并进行了同位素质量修正.这些结果与已有的实验值也十分一致.这里,12C32S+和12C32S+的光谱常数以及12C32S+高振动态的分子常数属首次报道.     

N2-Ar��Ƶ�ŵ���浪���ĵ�����������ģ��

N2-Ar射频放电等离子体广泛应用于微电子工业的刻蚀、氮化物薄膜的制备及金属表面氮化等技术领域。开发了N2-Ar混合气体容性耦合射频放电PIC/MC自洽模型,模型主要描述了e-,N2+,N+,Ar+等主要带电粒子的行为分布。等离子体的碰撞过程分别考虑了带电粒子(e-,N2+,N+,Ar+)与基态中性N2分子和Ar原子的21种碰撞反应过程。模拟结果表明,在纯N2及N2-Ar混合气体容性耦合射频放电中,各种带电粒子的数密度都在等离子体区达到最大值,且氮分子离子为主要粒子;在N2容性耦合射频放电中,加入10%氩气时,N+平均能量有所增加,在射频电极处两种氮离子(N2+,N+)高能粒子所占比例增加。本研究对认识N2-Ar射频放电等离子体过程微观机理具重要意义。     

VH_2~+分子离子的结构与势能函数

本文从VH2+分子离子基态的电子状态及其离解极限出发,采用B3PW91的方法,对V原子采用SVP基组,对H原子采用6-311 ++G基组优化出VH2+(X3A2)分子离子稳定构型的平衡核间距Re=0 .1631 nm,∠HVH =112 .3858°,同时计算出振动频率,并使用多体项展式理论方法,导出了基态VH2+分子离子的分析势能函数,该势能表面准确地再现了VH2+(C2v)平衡结构,然后根据势能函数等值图讨论了反应势能面的静态特征,并利用杂化轨道理论解释了VH2+分子离子的结构.     

NiCO分子结构与解析势能函数

用密度泛函理论的B3P86方法,对镍原子采用LANL2DZ收缩价基,碳原子和氧原子采用6-311+G~*基组,对NiC、NiO和NiCO体系的结构进行优化,计算表明:NiC分子基态为~1∑~+态,键长为R_e=0.16070 nm,离解能为3.62948 eV.NiO分子基态的平衡核间距为0.16784 nm,其电子态为~3∑~-,离解能为3.45119 eV,拟合得到Murrell-Sorbie势能函数;NiCO分子有两个线性稳定构型,其中一个构型为Ni—C≡O(C_(∞υ)),电子态为~1∑~+,平衡核间距为R_(NiC)=0.16621 nm,R_(co)=0.11519 nm,离解能为12.80476 eV,另一个为Ni—O≡C(C_(∞υ)),电子态是~1∑~+,平衡核间距为R_(co)=0.11470 nm,R_(NiO)=0.17636 nm,离解能为11.24679 eV.由微观过程的可逆性原理分析了分子的可能的离解极限,并用多体展式理论导出基态NiCO分子的势能函数,其等势面图准确地再现了NiCO分子的结构特征和离解能,由此讨论了Ni+CO,NiC+O,NiO+C分子反应的势能面静态特征.     

两种药物与金属离子的作用

研究了磺胺间甲氧嘧啶、诺氟沙星与Ce3+,La3+,Tb3+,Co2+,Fe3+作用体系的荧光和紫外特性。结果表明,La3+和Tb3+对磺胺间甲氧嘧啶的荧光起增敏作用,而Fe3+,Co2+,Ce3+使磺胺间甲氧嘧啶的荧光猝灭;Ce3+,La3+,Tb3+,Co2+,Fe3+对诺氟沙星的荧光均起猝灭作用。紫外的测定结果与荧光基本相同。     

Ti：Al2O3晶体的电子自旋共振谱研究

Ｔｉ：Ａｌ２Ｏ３晶体中的顺磁中心Ｔｉ＾３＋由于强烈的晶格自旋耦合而使其电子自旋共振吸收只有在液拟温度附近才能看到，本实验在液氮温度附近记录到由许多强的的吸收峰迭加于Ｔｉ＾３＋宽吸收线所组成的电子自旋共振谱，这些吸吸收峰被认为是Ａｌ２Ｏ３基质中的Ｆｅ＾３＋，Ｍｎ＾２＋，Ｃｒ＾３＋，Ｍｏ＾３＋，Ｆｅ＾２＋，Ｃｏ＾２＋等杂质的共振吸收及Ｔｉ＾２＋３Ａ２ｇ基态的双量子跃迁造成的。     

Dynamic nuclear polarization with single electron spins

We polarize nuclear spins in a GaAs double quantum dot by controlling two-electron spin states near the anticrossing of the singlet (S) and m(S)= +1 triplet (T+) using pulsed gates. An initialized S state is cyclically brought into resonance with the T+ state, where hyperfine fields drive rapid rotations between S and T+, "flipping" an electron spin and "flopping" a nuclear spin. The resulting Overhauser field approaches 80 mT, in agreement with a simple rate-equation model. A self-limiting pulse sequence is developed that allows the steady-state nuclear polarization to be set using a gate voltage.     

The microwave spectrum of cyanoformamide

The spectrum of cyanoformamide, NCCONH₂, has been measured between 18 and 40 GHz using a Hewlett-Packard spectrometer with Stark modulation. The molecule is somewhat unstable and could most conveniently be measured in a flow system. The quadrupole hyperfine structure due to the two nitrogen nuclei has been analyzed for the ground state, and quadrupole coupling constants, rotational constants, and centrifugal distortion constants have been determined for the ground state. A rough determination of the components of the electric dipole moment was possible from the Stark shifts of suitable transitions.     

Self-energy correction to the hyperfine splitting of the 1 s and 2 s states in hydrogenlike ions

The one-loop self-energy correction to the hyperfine splitting of the 1 s and 2 s states of hydrogenlike ions is calculated for both point and finite nuclei. The results of the calculation are combined with other corrections to find the ground state hyperfine splitting in lithiumlike ²⁰⁹Bi⁸⁰⁺ and ¹⁶⁵Ho⁶⁴⁺. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 1, 19–22 (10 July 1997) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Optical pumping and population transfer of nuclear-spin states of caesium atoms in high magnetic fields

Nuclear-spin states of gaseous-state Cs atoms in the ground state are optically manipulated using a Ti:sapphire laser in a magnetic field of 1.516T, in which optical coupling of the nuclear-spin states is achieved through hyperfine interactions between electrons and nuclei. The steady-state population distribution in the hyperfine Zeeman sublevels of the ground state is detected by using a tunable diode laser. Furthermore, the state population transfer among the hyperfine Zeeman sublevels, which results from the collision-induced modification \delta a(\bm S \cdot \bm I) of the hyperfine interaction of Cs in the ground state due to stochastic collisions between Cs atoms and buffer-gas molecules, is studied at different buffer-gas pressures. The experimental results show that high-field optical pumping and the small change \delta a(\bm S \cdot \bm I) of the hyperfine interaction can strongly cause the state population transfer and spin-state interchange among the hyperfine Zeeman sublevels. The calculated results maybe explain the steady-state population in hyperfine Zeeman sublevels in terms of rates of optical-pumping, electron-spin flip, nuclear spin flip, and electron-nuclear spin flip-flop transitions among the hyperfine Zeeman sublevels of the ground state of Cs atoms. This method may be applied to the nuclear-spin-based solid-state quantum computation.     

A new probe for local structure: Paramagnetic hyperfine structure in Nd3+ Mössbauer spectra

The⁴I_9/2 ground state of Nd³⁺ (4f³) is split by a crystal field of lower than cubic symmetry into five Kramer doublets. The magnetic hyperfine interactions can be calculated by using an effective magnetic hyperfine tensor Ã, which is obtained from the linear combination coefficients of the ground state doublet eigenvector. The hyperfine tensor à and the line shape depend strongly on the local structure of the system. Nondiagonal magnetic hyperfine interactions produce nonadiabatic relaxation. Corresponding lineshapes are calculated by means of the Clauser-Blume model and the eigenvalue treatment of superoperators. We found for Nd³⁺ in the investigated laser phosphate glass a network-forming function consistent with aC _3h orD _3h point symmetry.     

Analysis of hyperfine structure of Rare‐Earth Ions in Single Crystals by Electron Paramagnetic Resonance Spectroscopy

Electron paramagnetic spectroscopy of rare‐earth ions in single crystals is an interesting tool to analyze the hyperfine structure of the ground state of the rare‐earth. This can be useful for coherent spectroscopy and quantum information applications where the hyperfine structure of the electronic levels is used. Moreover, in some cases, the electron paramagnetic resonance hyperfine structure of interacting rare‐earth ions allows us to retrieve the isotropic exchange interaction between the two interacting ions. We illustrate these points with the hyperfine structure of Yb³⁺ ions in vanadate crystals, the hyperfine structure of Er³⁺ ions in Y₂SiO₅, and the hyperfine structure of Yb³⁺ pairs in CsCdBr₃.     

射频驱动精细结构能级跃迁引起的非线性效应

研究了射频驱动精细结构能级跃迁引起的电磁诱导透明（EIT）和电磁诱导吸收（EIA）的转化。通过采用射频场同时驱动激发态和基态精细结构能级跃迁,使系统中出现EIT和EIA。研究结果表明,调谐射频场频率从与基态精细结构能级共振到与激发态精细结构能级共振的过程中,EIT和EIA相互转化,而且射频场的拉比频率取值不同,EIT和EIA的变化规律也不同。     

调谐耦合场作用下的无反转光放大

 讨论了调谐耦合场作用下的Λ型三能级系统中的无反转光放大（AWI）现象,调谐耦合场同时激励两个基态精细结构能级与激发态能级之间的跃迁,使系统同时呈现电磁诱导透明（EIT）和自发诱导相干凹陷两种特性,而且当调节这个耦合场的频率失谐量在某一特定范围时,系统会在EIT信号上叠加出现AWI现象。研究结果表明：该系统中EIT和自发诱导相干凹陷之间存在能量转移现象,当EIT上出现AWI现象时,虽然激发态能级与基态能级之间没有出现粒子数反转,但是两个基态精细结构能级之间出现了粒子数反转。     

Calculation of the hyperfine structure of heavy H and Li like ions

The present status of calculations of the hyperfine splitting and the transition probability between the hyperfine splitting components in hydrogen and lithium like ions is discussed. The results of the calculations are compared with recent experimental data. A special attention is focused on the hyperfine splitting in hydrogen like lead and lithium like bismuth. It is shown that the theoretical prediction for the ground state hyperfine splitting in lead based on the single particle nuclear model for the Bohr-Weisskopf effect is in fair agreement with experiment. The theoretical prediction for the ground state hyperfine splitting in lithium like bismuth is improved due to more accurate calculations of the interelectronic interaction, QED, and nuclear corrections. This revised version was published online in August 2006 with corrections to the Cover Date.