YNbO4：Tm3+/Yb3+上转换发光特性研究

按照50Nb₂O₅-（46-x）Y₂O₃-4Yb₂O₃-xTm₂O₃（x=0.1,0.2,0.5,1,2）的配比方式,采用高温固相法制备出了掺杂Tm³⁺/Yb³⁺的YNbO₄晶体粉末。在980 nm红外光激发下,观测到波长为478,645,707 nm的上转换荧光,分别对应于Tm³⁺离子的¹G₄→³H₆、¹G₄→³F₄、³F₃→³H₆能级跃迁过程。利用上转换发射功率与980 nm激光器工作电流关系估算出跃迁过程吸收光子数目为2.72,2.69,2.01,从而确定出前两者为三光子吸收过程,最后一个对应于双光子吸收过程。运用Judd-Ofelt理论研究样品光谱特性,根据样品的吸收谱得到样品的谱线强度参数Ω_t（t=2,4,6）,进而得出理论振子强度及实验振子强度,二者均方根偏差δ_rms=1.299×10^-7。计算了Tm³⁺离子向下能级跃迁的跃迁几率、跃迁分支比等参数。最后得出结论：（1）³F₄能级寿命较长,适合作为上转换中间能级;（2）³H₅能级寿命较长,且³H₅→³H₆跃迁分支比（96.46%）接近100%,可用于产生1 216 nm激光。     

ON CALCULATION OF THE HYDROGEN NEGATIVE ION BETA SPECTRUM

The wavefunctions of the gxound states of negative hydrogen ion and the 10 first lowest ¹S states of helium atom are calculated by using a general wavefunction expansion form.The beta spectrum of the negative tritium ion is given by calculating a few most important transitions and including the remainder in terms of the closure approximation. Besides,the transition to ¹S(2S²) state is also studied.The result showed that the transition to a double-electron excited state of the helium atom may be very important. It indicates that there probably exists a resonance in the continuous spectrum.     

FPT-CNDO/INDO化学屏蔽常数计算方法及其在Mo和Co化合物中的应用

Semi -empirical molecular orbital methods within the framework of the finite perturbation theory , the FPT-CNDO/INDO methods , which consist of the FPT-CNDO/2 and FPT-INDO methods, are set up for the study of chemical shielding in transition metal compounds, and a corresponding computational program is developed on VAX 11/785 computer to establish a theoretical study of the transition metal chemical shielding by quantum chemistry methods. Application of the methods has been carried out in the calculation of 95Mo chemical shielding constants of mononuclear precursors [MoOnS4-n]2-(n=0-4). With the standard CNDO/INDO parameters a linear regression was obtained between the calculated results and the corresponding experimental data:δcal=(0.8345 δexp-43.83)ppm, with a correlation coefficient of 0.999. Investigation on the calculated electronic configuration confirms that in [MoOnS4_n]2- (n=0-4)95Mo chemical shifts are dominated by the d-orbital paramagnetic contribution arising from the d-d transition. Appl     

STUDIES OF P-MESCN DECAY BY THE TRANSITION POTENTIAL Vq-qqq OF A QUARK-ANTIQUARK PAIR CREATIOR MODEL

Decay rate of p-meson into two n-mesons was calculated by using the transition potential of a quark-antiguark pair creation model.The theoretical result is in good agreement with the experimental data .Also, the difference of decay widths for processes ρ^±π^±π⁰ and ρ⁰π⁺π^- was discussed.     

Analysis of 14C(π+, π-) 14O Reaction at 50 MeV

The ground states of ¹⁴C and ¹⁴O are described by a cluster wavefunction and the ¹⁴C_gs(π⁺, π^-) ¹⁴O_gs DIAS transition at 50 MeV is calculated in the Glauber theory. The results are in agreement with experimental data qualitatively and indicate that the effect of the l2 C core on the reaction is important.     

激光冷却OH分子的理论研究

采用高精度的多参考组态相互作用方法计算OH分子基态和第一激发态的势能曲线.为获得更精确的计算结果,在计算过程中考虑Davidson修正、标量相对论效应、核价相关效应和自旋轨道耦合效应.基于计算的Λ-S和?态的势能曲线,对一维径向薛定谔方程进行数值求解,得到各个电子态的光谱数据,与已报道的实验值和理论值相符合.获得OH分子的永久偶极矩、跃迁偶极矩、振动能级、Franck-Condon因子及辐射寿命,结果表明,A~2Σ~+→X~2Π跃迁具有高度对角化的Franck-Condon因子(0.9053)和短的辐射寿命(5.8363×10~(-7)s),符合激光冷却分子的条件.制定了激光冷却OH分子的具体方案,计算得到激光冷却跃迁A~2Σ~+→X~2Π所需的三束激光波长,主光束波长为307.1532 nm,两束重抽运激光波长为344.9163和349.7659 nm.计算结果为超冷OH分子的实验制备提供重要的理论依据.     

类氖CaⅪ和MnXVI2P53L或4L-2P54L1跃迁波长和能级的多组态Dirac-Fock计算

本文用MCDF-EAL计算模式,计算了可能成为超真空紫外区的类氖等离子体激光工作物质的CaⅪ与MnXVI类氖离子的1s²2s²2p⁵3l与1s²2s²2p⁵4l组态的多重态能级的能量值及3l-4l¹和4l-4l¹组态的各多重态能级间的可能的跃迁波长位,3l-4l¹跃迁波长的计算值与实验数据比较符合得很好。文中还预言了4l-4l¹的可能的跃迁波长,     

Low-lying electronic states of CuN calculated by MRCI method

The high accuracy ab initio calculation method of multi-reference configuration interaction(MRCI) is used to compute the low-lying eight electronic states of CuN.The potential energy curves(PECs) of the X~3∑~-,1~3Π,2~3∑~-,1~3△,1~1△,1~1∑~-,1~1Π,and ~5∑~- in a range of R=0.1 nm-0.5 nm are obtained and they are goodly asymptotes to the Cu(~2S_g) + N(~4S_u) and Cu(~2S_g)+N(~2D_u) dissociation limits.All the possible vibrational levels,rotational constants,and spectral constants for the six bound states of X~3∑~-,1~3Π,2~3∑~-,1~1△,1~1∑~-,and 1~1 Π are obtained by solving the radial Schrdinger equation of nuclear motion with the Le Roy provided Level 8.0 program.Also the transition dipole moments from the ground state X~3∑~- to the excited states 1~3Π and 2~3∑~- are calculated and the result indicates that the 2~3∑-X~3∑ transition has a much higher transition dipole moment than the 1~3Π-X~3∑~- transition even though the l~3Π state is much lower in energy than the 2~3∑~- state.     

QUANTUM EFFICIENCY AND MULTIPHONON NONRADIATIVE TRANSITION OF Er3+ IONS IN FLUORIDE GLASS

Optical absorption, emission and excitation spectra, lifetimes of ⁴S_3/2 state and ⁴F_9/2 state from 10K to 500K, and Raman spectra were measured for Er³⁺ ions in fluoride glass. The radiative transition probabilities were calculated on the basis of Judd-Ofelt theory. The nonradiative transition probabilities and the quantum efficiencies were determined by calculating the difference between the measured lifetimes and the calculated radiative transition probabilities. The temperature dependence of nonradiative transition provavility was investigated using the Huang-Rhys theory of multiphonon relaxation , in which two kinds of phonons as well as the parameter s were taken into consideration. A fairly good agreement of the theoretical calculation with the experimental results has been obtained. The value of s is estimated and the effect of s is discussed.     

取代基效应(SCS)与乙烯-α-烯烃共聚物的序列结构——7.氢化丁苯共聚物(HBS)

测定了两个氢化丁苯共聚物样品的¹H、¹³C NMR谱。通过处理文献中的¹³C NMR谱数据得到了-C₂H₅和-C₆H₅的SCS参数。利用乙烯-α-烯烃共聚物的SCS方法结合DEPT NMR实验技术重新归属了该共聚物的¹³C NMR谱。明确指出,氢化丁苯共聚物分子链中主链任何一个乙烯单元的两个CH₂在序列分布上分属于二元组和三元组。CH则用三元组来表征。最后,对HBS共聚物的序列分布进行了计算。     

Fission of Th and U in the interaction with negative muons

Muon-induced fission of ²³²Th and ²³⁸U was studied, measuring the time correlation between stopping muons, fission events and electrons.

The measured muon lifetimes are τ_μ(²³²Th) = 77.3±0.3 ns and τ_μ(²³⁸U) = 77.1±0.2 ns. After prompt fission the muon was found to be attached predominantly to the heavy fragment with a lifetime for ²³²Th of 132±7 ns and for ²³⁸U of 134±4 ns. The probability for muon conversion was found to be a few percent per fission event.

Indications were found that the muonic shape isomer is populated in ²³⁸U when the nucleus is excited in a radiationless muonic transition.     

The transition probability of DJ-F0 and hole-burning quantum efficiency in the SryBa1−yFCl0.5Br0.5:Sm system

We report the changes of the ⁵D_J-⁷F₀(J = 2, 1, 0) transition probability with composition y and its effect on the hole burning quantum efficiency in the Sr_yBa_1−yFCl_0.5Br_0.5:Sm²⁺ system. We observed that the ⁵D_J-⁷F₀ transition probability increases with the increase of Sr concentration. This result is attributed to the reduction of the energy separation between the ⁵D_J level and the 4f5d bands, which makes the electron wave functions of ⁵D_J states mix further with that of the 4f5d states. The dependence of the hole-burning quantum efficiency on the 5D_J-⁷F₀ transition probability was derived by the dynamical equations of the spectral hole burning of divalent samarium. Furthermore, the hole-burning experiments in SrFCl_0.5Br_0.5:Sm²⁺ and BaFCl_0.5:Sm²⁺ were performed under the same conditions. The experimental results present that the hole-burning quantum efficiency of SrFCl_0.5Br_0.5:Sm²⁺ is higher than that of BaFCl_0.5Br_0.5:Sm²⁺.     

Identification of Bandhead Spin and Identical Bands for Odd-A Nuclei in $A\sim190$ Superdeformed Mass Region

The dynamical moment of inertia is estimated with its even-power expansion of the rotational frequency and in accordance we determine the intermediate spins of the superdeformed (SD) rotational bands. Using Marquardt method of nonlinear least-squares routines, we determine the expansion coefficients by fitting the proposed dynamical moment of inertia with its recent experimental data of the SD nuclei in the A=190 mass region. The comparison between our theoretical and available experimental data for the dynamic moment of inertia and spin shows good agreements. Also, we have calculated the static moment of inertia at three alternative values of spin. The value of spin at which the two moments of inertia are nearly equals is to be regarded as a bandhead spin of the corresponding band. These studies are carried out for eighteen bands of odd-A nuclei of the superdeformed region 190, namely ¹⁸⁹Hg(b1), ¹⁹¹Hg(b1, b2, b3, b4), ¹⁹³Hg(b2, b3, b5), ¹⁹⁵Hg(b1, b2, b3, b4), ¹⁹³Tl(b1, b2, b3, b5), ¹⁸⁹Tl(b1), and ¹⁹⁷Bi(b1). We also notice the occurrence of identical SD bands with near identical transition energies among the considered SD bands.     

The probability of non-radiative decay of the 3d level in muonic Np

The X-ray spectrum of muonic ²³⁷Np has been investigated with stopped muons in a NpO₂ target, containing about 10 g of ²³⁷Np. The probability of the radiationless muonic 3d→1s transition in ²³⁷Np, (9±4)%, was obtained by comparing the relative intensities of the main muonic X-ray transitions in singles and coincidence spectra. The coincidences were gated by the 2p→1s transitions.     

硼原(离)子内壳激发高自旋态能级和辐射跃迁

采用Rayleigh-Ritz变分方法计算了B原子(离子)内壳层激发高自旋态(~(4,5,6)L,L=S,P)里德伯系列的能量和精细结构劈裂,利用截断变分方法改进非相对论能量,并利用一阶微扰理论计算了相对论能量修正和质量极化效应修正,利用屏蔽的类氢公式计算了量子电动力学效应和高阶相对论效应,从而得到了高精度的组态能量.利用精确计算的波函数,计算了这些高自旋态的电偶极辐射跃迁波长、振子强度和辐射跃迁概率.通过长度规范和速度规范计算的振子强度的一致性证明了本文计算的波函数是精确的.相比其他理论计算结果,本文计算的高自旋态的能级及跃迁波长数据与实验数据符合得更好.对于一些高位的内壳层激发高自旋态,相关的能级和跃迁数据为首次报道,本文的计算结果对相关实验光谱谱线标定具有重要意义.     

Configuration interaction study on low-lying states of AlCl molecule

High-level ab initio calculations of the Λ–S states for aluminum monoiodide(Al Cl) molecule are performed by utilizing the explicitly correlated multireference configuration interaction(MRCI-F12) method. The Davidson correction and scalar relativistic correction are investigated in the calculations. Based on the calculation by the MRCI-F12 method, the spin–orbit coupling(SOC) effect is investigated with the state-interacting technique. The adiabatic potential energy curves(PECs) of the 13 Λ–S states and 24 Ω states are calculated. The spectroscopic constants of bound states are determined,which are in accordance with the results of the available experimental and theoretical studies. Finally, the transition properties of 0~+(2)–X0~+, 1(1)–X0~+, and 1(2)–X0~+ transitions are predicted, including the transition dipole moments(TDMs),Franck–Condon factors(FCFs), and the spontaneous radiative lifetimes.     

THE EXCITATION OF 9.5 MeV LEVEL OF 13C IN QUASI-Δ33 DOORWAY STATE MODEL

We have studied the excitation mechanism of 9.5 MeV Level of ¹³C in ¹³C(π^±,π^1±)¹³C (9.5 MeV) inelastic scattering in the framework of Quasi-X33 Doorway State. Model .Assuming. the transition to 9.5 MeV state is of a pure neutron has received satisfactory agreement with experiment. The results strongly suggest that the spin and parity assignment of state,9.5 MeV of ¹³C should be Jπ=9/2⁺.     

基于ab initio的BD~+离子激光冷却理论研究

基于相关一致基组aug-cc-pV5Z,采用内收缩多参考组态相互作用方法计算了BD~+离子两个最低解离极限B~+(~1Sg)+D(~2Sg)和B+(~3Pu)+D(~2Sg)对应的5个Λ—S态(X~2Σ~+,A~2Π,B~2Σ+,a~4Π和b~4Σ~+)的势能曲线和跃迁偶极矩.根据计算结果,求解核运动的径向薛定谔方程得到相应电子态的振-转光谱常数、Franck-Condon(F-C)因子和振动能级辐射寿命.其中A~2Π—X~2Σ~+的F-C因子(f_(00)=0.923)、辐射寿命(τ=235 ns)满足激光直接冷却的条件.因此,我们基于分子转动跃迁提出了一个可实现Doppler激光冷却的光循环方案:A~2Π_(1/2)(υ′=0)—X~2Σ+(υ′′=0,1),其中υ′=0中包含2个转动能级,υ′′=0和υ′′=1中分别包含6个和4个转动能级.根据方案,模拟了激光冷却过程中的分子布居数动力学变化过程,并计算了初速度为100 m/s的BD~+,历经5.4 ms散射1150个光子可减速到4.6 m/s、温度为13 mK.     

Nb XIII离子3d94s2, 3d94s4p, 3d94p2 组态能级结构与跃迁的理论研究

用准相对论Hartree-Fock方法对Nb XIII离子二电子激发组态3d⁹4s², 3d⁹4s4p, 3d⁹4p² 的能级结构做了全面系统的理论计算研究.在对已有研究结果分析的基础上, 运用最小二乘方法对径向积分参数进行了优化计算, 得到了与这些组态有关的电偶极允许跃迁的谱线波长和跃迁概率.计算结果与最新的实验值做了对比分析, 表明本文计算结果是准确的. 研究发现, 波长40.92 nm的谱线, 属于3d⁹4s(¹D)4p²F_7/2–3d⁹ (²D)4s^{2 2}D_5/2 的跃迁谱线, 而不属于3d⁹4s (¹D)4p⁴D_7/2–3d⁹(²D)4s^{2 2}D_5/2 的跃迁谱线, 即上谱项能级为²F_7/2, 而不是⁴D_7/2. 关键词： Nb XIII离子 二电子激发组态 谱线波长 跃迁概率