镉原子J=1偶宇称能谱的MQDT分析

在多通道量子数亏损理论(MQDT)的基础上,对镉原子J=1偶宇称的MQDT模型进行了分析,并利用MQDT波函数给出了计算高激发态寿命的一般方法,计算并预言了5sns12125snd21321(6≤n≤23)这两个Rydberg系列的寿命,拟合出了它们的寿命计算公式:5sns21211系列为τ=0.8980v2n.755;5snd12231系列为τ=0.3628v2n.829.     

V+20离子的能量和偶极振子强度

用全实加关联方法计算了类锂V+20离子 1s2nl(l=s,p, d;n≤9) 态的电离势和精细结构.依据单通道量子亏损理论, 确定了这三个Rydberg系列的量子数亏损.用这些作为能量的缓变函数的量子亏损,可以实现对任意高激发态(n≥10)的能量的可靠预言.用在计算能量过程中确定的波函数,计算了V+20离子1s22s-1s2np及1s22p-1s2nd (n≤9)跃迁的振子强度.将这些分立态振子强度与单通道量子亏损理论相结合,得到在电离域附近束缚态间的偶极跃迁振子强度以及束缚态-连续态跃迁的振子强度密度,从而将V+20离子的这一重要光谱特性的理论预言外推到整个能域.     

汞原子6sns 3S1,6snd 3D1 Rydberg系列的寿命

利用多通道量子数亏损理论计算了汞原子6sns^3S1(n=11～25),6snd^3D1(n=12～24)两个Rydberg系列的能级和寿命,给出了这两个系列寿命所遵循的公式,6sns^3S。系列为r=0．814v^2.835(ns),6snd^3D1系列为r=0．302v^2.926ns),其中v为有效量子数。     

Ti19+离子1s23d-1s2nf的跃迁能和振子强度

用全实加关联方法计算了类锂Ti19+离子1s23d～1s2nf(4≤n≤9)的跃迁能、振子强度及1s2nf(n≤9)态的精细结构劈裂.通过确定该Rydberg系列的量子数亏损,进而实现对任意高激发态(n≥10)的能量的可靠预言.将上述分立态振子强度与单通道量子亏损理论相结合,得到在电离阈附近束缚态间的跃迁振子强度与束缚态-连续态跃迁的振子强度密度,从而实现了Ti19+离子量子跃迁特性的全能域理论预言.     

Zn27+离子的精细结构和偶极振子强度

用全实加关联(FEPC)方法计算了类锂Zn27 离子1s2np(n≤9)态的精细结构.依据单通道量子亏损理论,确定了1s2nl(l=s,p)Rydberg系列的量子数亏损.用这些作为能量的缓变函数的量子亏损,可以实现对任意高激发态(n≤10)的能量的可靠预言.用在计算能量过程中确定的波函数,计算了Zn27 离子1s2 ns-1s2np(n≤9)跃迁的振子强度,三种规范下的计算结果符合的很好.将分立态的振子强度结果与单通道量子亏损理论相结合,计算在电离阈附近分立态间的束缚态.束缚态跃迁振子强度与束缚态-连续态跃迁的振子强度密度,实现了具有较大核电荷数的类锂离子量子跃迁特性的全能域理论预言.     

Ti19+离子1s23d-1s2nf的跃迁能和振子强度

用全实加关联方法计算了类锂Ti19 离子1s23d-1s2nf(4≤n≤9)的跃迁能、振子强度及1s2nf(n≤9)态的精细结构劈裂.依据单通道量子亏损理论,确定了该Rydberg系列的量子数亏损.用这些作为能量的缓变函数的量子亏损,可以实现对任意高激发态(n≥10)的能量的可靠预言.将这些分立态振子强度与单通道量子亏损理论相结合,得到在电离阈附近束缚态间的偶极跃迁振子强度以及束缚态-连续态跃迁的振子强度密度,从而实现了Ti19 离子量子跃迁特性的全能域理论预言.     

Fe23+离子1s22s-1s2np的跃迁能和偶极振子强度

用全实加关联方法计算了类锂Fe23 离子1s22s-1s2np(2≤n≤9)的跃迁能和1s2np(n≤9)态的精细结构.依据单通道量子亏损理论,确定了Rydberg系列1s2np的量子数亏损.用这些作为能量的缓变函数的量子亏损,可以实现对任意高激发态(n≥10)的能量的可靠预言.用在计算能量过程中确定的波函数,计算了Fe23 离子1s22s-1s2np(2≤n≤9)跃迁的振子强度.将这些分立态振子强度与单通道量子亏损理论相结合,得到该离子从基态到电离阈附近高激发束缚态间的偶极跃迁振子强度以及束缚态-连续态跃迁的振子强度密度,从而将Fe23 离子的这一重要光谱特性的理论预言外推到整个能域.     

Mn22+离子1s22s-1s2np的偶极跃迁能和振子强度

用全实加关联方法计算了类锂Mn22 离子1s22s-1s2np(2≤n≤9)的偶极跃迁能和振子强度.1s2np(2≤n≤9)态的精细结构通过计算自旋-轨道与自旋-其他轨道相互作用算符的期待值确定.依据单通道量子亏损理论,确定了Rydberg系列1s2np的量子数亏损.从而可以用这些作为能量的缓变函数的量子亏损,实现对任意高激发态(n≥10)的能量的可靠预言.将这些分立态振子强度与单通道量子亏损理论相结合,得到在电离阈附近束缚态-束缚态跃迁振子强度以及束缚态-连续态跃迁的振子强度密度,从而将Mn22 离子的这一重要光谱特性的理论预言外推到整个能域.     

铅原子奇宇称Rydberg系列寿命的研究

在多通道量子数亏损理论(MQDT)的基础上,利用已给出的用MQDT波函数统一计算高激发态寿命的方法,计算并预言了J=1奇宇称两个Rydberg系列的寿命,在利用MQDT计算时,确定了6p6d3/2[3/2]₁⁰的能级位置.     

弯曲振动对CS_2分子~1B_2(~1Σ_u~+)态预解离寿命的影响

在209.5～216nm,采用光解碎片激发(PHOFEX)谱技术,对CS2分子1B2(1Σ+u)态预解离寿命进行了 考察.测量在超声射流中进行.信号来自解离碎片CS(A1Π,v′=0←X1Σ+,v″=0)Q支带头的激光诱导荧光 (LIF).预解离寿命是通过对谱带进行拟合来提取的.拟合中假定基态转动布居为Boltzmann分布,寿命加宽的转 动谱线为Lorentz线形.通过拟合共获得1B2(1Σ+u)态13个跃迁所对应的预解离寿命,其中6个数据是新得到的. 结果表明,基态振动角动量量子数l或激发态转动角量子数K(K=l)对预解离寿命有明显的影响.对于激发态的 同一振动能级,较大的K对应于较短的预解离寿命.实验中采用可加热的射流喷嘴,用以提高热带激发的强度, 以改善对较大转动角量子数K的影响的考察.     

Perturbation of the excited states of the hydrogen atom and hydrogen-like ions by a neutral atom

Owing to the degeneracy of the energy levels, the wavefunction of the electron in the excited states of the hydrogen atom and hydrogen-like ions perturbed by a neutral atom B is significantly different from the wavefunction of the unperturbed state. The perturbed function has a wide high maximum in the region of atom B, which is explained by multiple collisions of the electron with atom B, because the classical trajectories in the Coulomb field are closed and the size of atom B is much smaller than the size of the excited-state orbit. The radiative lifetimes of the excited states are much larger than those of unperturbed states. The orbital angular momentum L of the excited electron is strongly changed in collisions with atom B owing to the quantum interference or mixing of the temporal phases of adiabatic wavefunctions. The cross sections for such a change in the orbital angular momentum are several orders of magnitude larger than the cross sections found in early investigations in the approximation of the single collision of the electron with atom B.     

The progress towards terahertz quantum cascade lasers on silicon substrates

A review is presented of work over the last 10 years which has been aimed at trying to produce a Si‐based THz quantum cascade laser. Potential THz applications and present THz sources will be briefly discussed before the materials issues with the Si/SiGe system is discussed. Waveguide designs and waveguide losses will be presented. Experimental measurements of the non‐radiative lifetimes for intersubband transitions in Si_1‐xGe_x quantum wells will be presented along with theory explaining the important scattering mechanisms which determine the lifetimes. Examples of p‐type Si/SiGe quantum cascade designs with the experimental electroluminescence will be reviewed and examples of n‐type Si‐based designs will be presented. In the conclusion designs and structures will be discussed with the greatest potential to achieve an electrically pumped Si‐based THz laser.     

Theoretical study of quantum-confined band-edge shifts and radiative lifetimes in oxidized Si(001) quantum films: comparison with experiment for Si/SiO2 quantum wells

The electronic structure and radiative lifetimes of Si(001) quantum films terminated by SiO₄ tetrahedra, which simulate Si/SiO₂ quantum wells (QWs), are calculated by the extended Hückel-type non-orthogonal tight-binding method. It is found that calculated band-gap widenings and radiative lifetimes account for band-edge shifts and photoluminescence (PL) peak shifts and lifetimes measured in amorphous-Si/SiO₂ QWs, suggesting that quantum confinement effects on the extended band-edge states in the amorphous-Si layer are responsible for the observed results. However, it is shown that band-edge shifts and PL energies and lifetimes observed in crystalline-Si/SiO₂ QWs cannot be reproduced properly by the interface model proposed in this study, implying that further studies are needed on the atomic structure of the crystalline-Si/SiO₂ interface.     

Lifetimes of Rydberg states of Eu atoms

The radiative lifetimes of the Eu 4f76snp(8PJ or10PJ)Rydberg states with J=5/2 and 11/2 are investigated with a combination of multi-step laser excitation and pulsed electric field ionization,from which their dependence on the effective principal quantum number is observed.The lifetimes of 21 states are reported along with an evaluation of their experimental uncertainty.The influence of blackbody radiation,due to the oven temperature,on the lifetime of the higher-n states is detected.The non-hydrogen behavior of the investigated states is also observed.     

Ionization Potentials and Quantum Defects of 1s2np2P Rydberg States of Lithium Atom

In this work, ionization potentials and quantum effects of 1s²np²P Rydberg states of lithium are calculated based on the calibrated quantum defect function. Energy levels and quantum defects for 1s²np²P bound states and their adjacent continuum states are calculated with the R-matrix theory, and then the quantum defect function of the 1s²np (n≥7) channel is obtained, which varies smoothly with the energy based on the quantum defect theory. The accurate quantum defect of the 1s²7p²P state derived from the experimental data is used to calibrate the original quantum defect function. The new function is used to calculate ionization potentials and quantum effects of 1s²np²P (n≥7) Rydberg states. Present calculations are in agreement with recent experimental data in whole.     

Radiative transfer over small distances from a heated metal

Published works have predicted that the radiative transfer from a heated metal to a lossless dielectric a short distance away is many orders of magnitude times the free-space Planck density. It is shown analytically that the radiative transfer from a heated metal to a lossless dielectric of index n(3) is n(3)(2)e(13) times the free-space Planck density, where e(13) is the emissivity of the metal radiating into the lossless dielectric. This radiative transfer is never larger than n(3)(2) (approximately one order of magnitude for semiconductors in the infrared) times the free=space Planck density. The expressions presented show that the maximum radiative transfer from a lossy metallic heat source with a dielectric function of imaginary part ?(I) must be proportional to n(3)(3)/ radical?(I), of which a factor of n(3)(2) arises from the power density within a dielectric and a factor of n(3)/ radical?(I) arises from the emissivity of a metal radiating directly into a dielectric.     

Artificial Rydberg atom

We analyze bound states of an electron in the field of a positively charged nanoshell. We find that the binding and excitation energies of the system decrease when the radius of the nanoshell increases. We also show that the ground and the first excited states of this system have remarkably the same properties of the highly excited Rydberg states of a hydrogen-like atom, i.e., a high sensitivity to the external perturbations and long radiative lifetimes.     

Theoretical calculation of energy levels and radiative lifetimes of Tl I

Considering the perturbation, the results of theoretical calculation of five Rydberg series energy levels 6s2ns^2S1/2 （n = 7 - 20）, 6s^2nd^2D3/2 （n = 6 - 20）, 6s^2nd^2D5/2 （n = 6 - 20）, 6s^2np^2P1/2^0 （n = 7- 20）, and 6s^2np^2P3/2^0 （n = 7-20） for Tl I are presented using the weakest bound electron potential model （WBEPM） theory. Furthermore, the radiative lifetimes of this five series are also calculated. The calculated values of energy levels and lifetimes are in good agreement with the experimental results.     

Semiclassical theory of the radiative-collisional cascade in a Rydberg atom

We have developed a two-dimensional semiclassical model of the radiative-collisional cascade for hydrogen-like systems. We describe the collisions with electrons and ions by classical diffusion in the space of principal and orbital quantum numbers and use an iterative procedure that consistently takes into account the quantum nature of the radiative cascade for radiative transitions. The model establishes the correspondence between the quantum and classical approaches and indicates that the latter cannot be directly used to calculate the population kinetics of highly excited atomic states. Our calculations of the two-dimensional populations of highly excited atomic hydrogen states for selective, three-body, and photorecombination sources of population allow the data of one-dimensional kinetic models to be refined. The calculated intensities of recombination lines demonstrate the degree of nonequilibrium of the Rydberg state populations under typical astrophysical plasma conditions.