基于量子干涉效应的多能级系统自发辐射研究

本文了一个多能级系统的量子干涉效应,该能级中三个相邻分离能级通过一相干驱动场与一个低能级耦合,同时通过真空模与另一低能级耦合。     

多能级原子的量子跳跃与连续量子测量

研究了多能级原子的量子跳跃行为,构造出多能级原子系统光学Block方程的形式解．证明了Mollow的纯态描述理论不适用于多能级原子,为此,发展了混合态描述理论,得出了多能级原子的重置密度矩阵为混合态的结论．最后,讨论了多能级原子的量子跳跃与连续量子测量的联系． 关键词：     

非破坏性研究半导体材料特性参数

测量了元素和化合物半导体单晶材料的常温、低温下的表面光电压,推导了有关计算公式,计算得出材料的少子扩散长度、深能级和表面能级位置,禁带宽度和化合物组分;由双能级复合理论,研究了少子扩散长度与深能级的关系,计算了深能级浓度和参数;计算结果与其他方法的测量实验值基本一致. 关键词：     

在WBEPM理论中受扰里德堡能级研究

在最弱受约束电子势模型理论下,研究了外来微扰能级对里德堡能级系列的影响,给出了确定外来微扰能级位置的方法.依此计算了钡原子6snp(n≥15).P1和6snd(n≥9)3D3两个里德堡能级系列的量子数亏损和能级.计算结果和实验值的绝对误差在1 cm-1以内,达到了较高的精度.     

对称强双色共振场中弛豫效应对二能级系统斯塔克分裂的影响

本文应用半径典理论、密度矩阵方法和探索场中二能级系统的能级斯塔克(Stark)分裂。指出与无弛豫效应相比较,弛予效应不仅改变了由光学斯塔克效应所产生的分裂能级的权重、展宽了这些能级,而且还出现新的分裂能级。     

同向电场磁场中氢原子的能级分裂

用通用软件Mathematica和简并微扰论计算了氢原子n=3~7能态在一对同方向电磁场中的能级分裂(不考虑自旋).数值结果表明:在许多情况下,一级修正可以使能级简并完全解除,这时总体能级分裂不是等间距的;但在一定条件下,总体能级分裂是等间距的,此时能级简并不能完全解除,只分裂为3n-2个不同能级.现有文章的结论是欠周全的.     

简并四波混频中的能级交叉效应

我们用微扰方法计算了近简并准二能级系统的三阶非线性极化率x⁽³⁾(-ω;ω,ω,-ω)。研究了简并四波混频的能级交叉效应,并与共振荧光的能级交叉效应比较。指出简并四波混频的能级交叉效应可用来测量上能级及下能级的弛豫速率。 关键词：     

Ce:BaTiO3晶体中两个深陷阱能级引起的光折变光栅暗衰减特性

对Ce:BaTiO3晶体中光折变光栅的暗衰减特性进行了实验研究，观测到了晶体禁带中的Fe离子和Ce离子两个深陷阱能级同时参与了光折变过程。在单深能级模型和浅－深能级模型的基础上，提出了简化的双深能级模型，并根据该模型定量地分析了Fe离子和Ce离子每个深陷阱能级在不同光栅波矢、不同光栅写入光强时对总空间电场以及光折变光栅的贡献。     

锡原子奇宇称5pnd和5pns J = 1, 2 Rydberg系列的多通道量子亏损理论研究

利用多通道量子亏损理论（MQDT）,对锡原子奇宇称5pnd和5pns组态的J = 1,2简并受扰Rydberg系列能级进行了理论分析研究. 通过拟合实验能级,得到了MQDT优化参数,所得理论能级值与文献报道的实验结果符合得很好. 由算得的通道混合系数,分析讨论了通道相互作用特性,确定了所有能级的原子态命名. 本文结果有助于人们更好地了解锡原子高激发态的能级结构和组态相互作用特性.     

磁通量对二维谐振子的量子能级密度的影响

利用周期轨道理论,我们计算了在不同情况下,一个粒子在二维谐振子势中存在和不存在磁通量时的量子能级密度.重点讨论了磁通量对量子能级密度的影响.计算结果表明:当二维谐振子势的频率比值是有理数时,量子能级是分立的,能级密度中的每一条峰正好对应一个量子能级.然而,当频率比是无理数时,能级密度发生振荡,当加上磁通量后,振荡减小.这可以看作是Aharonov-Bohm效应的结果.     

Radiative lifetimes of some excited states of neutral xenon

The radiative lifetimes of ten levels belonging to the nf (n=4-7) and three levels belonging to the ns (n=8,9) configuration of XeI have been measured using the high frequency deflection technique together with a delayed coincidence single-photon counting arrangement. Lifetimes of some of the levels have been measured for the first time. The results have been compared with other experimental and theoretical values.     

DLTS studies of deep levels in semiconducting N-CdTe single crystals

Deep levels created by annealing of Al-doped n-CdTe single crystals have been studied by the Deep Level Transient Spectroscopy (DLTS) technique. Eight levels have been detected in the energy range from 0.04 to 0.07 eV below the conduction band edge. The thermal ionization energies and the capture cross sections for electrons in these levels have been obtained. The dependence of concentrations of the levels on the Cd vapor pressure during annealing and on the cooling process after annealing has been determined.     

Energy levels and spectral lines of Ne VII

All experimental data on Ne VII, including previously unpublished beam-foil spectroscopy data, have been compiled and critically evaluated. More than a hundred spectral lines have been newly identified. For 40 transitions, the previous identifications have been revised. These revisions resolved all existing contradictions between previously published interpretations of the spectrum. An optimized level scheme has been derived from the total list of observed lines. About a hundred new energy levels have been found, including several highly excited hydrogenic levels. Based on these newly determined levels, as well as on the analysis of theoretical data, the ionization potential has been newly determined with improved confidence. Electronic supplementary material Online Material     

Two colour multiphoton ionization spectroscopy of uranium from a metastable state

Using two pulsed tunable dye lasers, a two colour multiphoton ionization process has been utilised to explore the higher energy levels of uranium. One hundred and thirty eight new UI levels have been observed in the 37540–38420 cm^–1 region. J assignments of these levels have been suggested on the basis of their excitation from intermediate levels with known and contiguous J values. In eight cases the J assignments are unique.     

A study of the 75As(n,n'γ)75As reaction

The de-excitation gammas following the inelastic scattering of neutrons from ⁷⁵As have been studied for incident neutron energies from 1300 to 2800 keV in steps of 100 keV. The energy levels and the branching ratios of their decays have been deduced from excitation function measurements: 58 energy levels have been found in the excitation energy region below 2.8 MeV, twelve of which are reported for the first time in this work. The experimental excitation functions and angular distributions have been compared with the theoretical predictions based on the statistical theory of the compound nucleus. Spin and parity assignments for the levels and multipolarities for the decays are proposed for excitation energies of levels up to 2300 keV.     

Study of (d, α) reactions on 94Zr and 96Zr

The nuclear structure of ⁹²Y and ⁹⁴Y has been investigated by the (d, α) reaction on ⁹⁴Zr and ⁹⁶Zr with 11.5 MeV deuterons. Some new levels have been seen in ⁹²Y and ⁹⁴Y. The angular distributions for these levels have been measured. A zero-range DWBA analysis has been carried out for these distributions and spin-parity assignments have been made for the new levels.     

Lifetime measurement of some excited states belonging to the 3p<Superscript>4</Superscript>nd (n=4–6) configuration of ArII

The radiative lifetimes of eight levels belonging to the 3p⁴nd (n=4–6) configuration of ArII have been measured using high frequency deflection technique together with a delayed coincidence single photon counting arrangement. Lifetimes of some of the levels have been measured for the first time. The results have been compared with other experimental and theoretical values.      

Hyperfine-structure measurements and new levels evaluation in singly ionized praseodymium

Results of systematic studies of the hyperfine structure of singly ionized praseodymium are presented. For many of the known energy levels the hyperfine constants A and B have been measured more precisely and found consistent with previous literature data. Identification of some new energy levels has also been performed. The hyperfine structure of some unclassified lines has been recorded by the method of laser induced fluorescence in a hollow cathode discharge. J quantum numbers and A-values for upper and lower levels have been determined. Identification has been achieved through comparison of the obtained results with those for known levels. Three new low-lying levels in singly ionized praseodymium have been discovered. Some of the recorded unclassified lines involve two new levels and their identification requires further investigations. Received 28 February 2001 and Received in final form 3 July 2001     

Electronic characteristics of InAs self-assembled quantum dots

Deep-level transient spectroscopy and photoluminescence studies have been carried out on structures containing self-assembled InAs quantum dots formed in GaAs matrices. The use of n- and p-type GaAs matrices allows us to study separately electron and hole levels in the quantum dots by the deep-level transient spectroscopy technique. From analysis of deep-level transient spectroscopy measurements it follows that the quantum dots have electron levels 130 meV below the bottom of the GaAs conduction band and heavy-hole levels at 90 meV above the top of the GaAs valence band. Combining with the photoluminescence results, the band structures of InAs and GaAs have been determined.     

Nuclear orientation of171Lu and173Lu

The decays of¹⁷¹Lu and¹⁷³Lu have been studied by means of nuclear orientation. External perturbations of two¹⁷¹Yb levels have been observed. Unambiguous spin assignments have been made for several levels in¹⁷¹Yb and mixing ratios of the transitions in¹⁷¹Yb and¹⁷³Yb have been deduced. The properties of the¹⁷¹Yb and¹⁷³Yb rotational bands have been studied using the quasiparticle-phonon model including a Coriolis interaction.