用超跃迁阵模型分析金等离子体光谱)

在局域热动平衡条件下,采用超跃迁阵模型分析热密金等离子体的光谱.阐述了束缚束缚跃迁下的超跃迁阵理论模型,给出了在温度T=0.5 KeV,密度ρ=10.0 g/cm3时,金等离子体中4d→5f的部分光谱.     

Au激光等离子体M带5f-3d跃迁的光谱参数

用超组态碰撞辐射模型模拟非局域热动力学平衡中Au的M带谱5f-3d跃迁的离子电离态特性，激光等离子体的光谱跃迂参数是必不可少的。利用多组态Dirac-Fock广义扩展平均能级方法，用GRASP^2系统地计算了激光Au等离子体中类铁金离子-类锗金离子的M带谱5f-3d的光谱跃迁波长．跃迁几率和振子强度，计算中考虑了重要的核的有限体积效应、Breit修正和QED修正，所得结果和最近的实验数据及理论计算值进行了比较。此结果可应用于对激光等离子体的模拟和诊断。     

金激光等离子体X射线精细结构谱研究

在“星光-Ⅱ”钕玻璃激光装置上,聚焦三倍频激光束于真空室内Au微点靶表面,形成高剥离 态热等离子体光源.用Pentaerythritol(PET)(2d=0.8742nm)平晶谱仪,摄录了Au离子在0.3 —0.4nm范围内的X射线发射谱.基于相对论性多组态Dirac-Fock程序包,建立了相对论性次 组态平均能计算程序,结合自旋-轨道劈裂跃迁系(SOSA)理论,计算了Au离子类Cu至类Ge离 子细致带结构谱孤立峰的中心波长和半高全宽.26条3d—nf(n=5,6,7)类Ni至类As离子子组态 跃迁形成的 关键词： 金 精细结构 自旋-轨道劈裂跃迁系 不可分辨跃迁系 X射线     

Au等离子体M带5f-3d跃迁透射谱的理论模拟

基于细致组态(DCA)方法和跃迁系列群 (UTA) 模型,采用全相对论处理并结合量子亏损理论,计算了金Au激光等离子体的M带5f-3d跃迁的透射谱, 给出了金等离子体在不同电子温度和电子密度的时空电离态特性,平均电离度,离子丰度和离子内各能级的布居数,并模拟出Au等离子体的M 带5f-3d跃迁的细致谱线,其计算结果可对激光等离子体透射谱的电子温度和电子密度进行精密诊断.     

金激光等离子体带谱的精细结构分析

在自旋轨道劈裂阵(spin-orbit-split Array )模型下,计算得出激光金等离子体的Co-like、Ni-like、Cu-like、Zn-like 、Ga-like的5f-3d、5p-3d、5s-3p、4f-3d、4d-3p、4p-3d的波长和半宽度(FWHM),并与实验测得的光谱数据相比较,结果比较一致.     

激光金等离子体中Au47+、Au53+的离子结构和光谱分析

根据扩展的相对论多组态狄拉克-福克（Dirac-Fock）理论,采用“多功能相对论原子结构程序（GRASP^2）”,考虑量子电动力学（QED）效应和布雷特（Breit）修正,选用二参量费米有限核电荷分布和扩展平均能级模型,并考虑组态问的相互作用和电偶极跃迁,计算了类锗Au^47＋、类铁Au^53＋的跃迁波长,跃迁几率和振子强度,计算的波长与实验值符合较好。研究表明,在类锗^47＋、类铁Au^53＋的跃迁中,3d-4f是一条较强的跃迁通道。计算所得的波长值对金等离子体的能级寿命、电荷态分布和平均电离度研究有一定的参考价值。     

金激光等离子体带谱的精细结构分析

在自旋轨道劈裂阵(spin—orbit—split Array)模型下，计算得出激光金等离子体的Co-like、Ni—like、Culike、Zn—like、Ga—like的5f-3d、5p-3d、5s-3p、4f-3d、4d-3p、4p-3d的波长和半宽度(FWHM)，并与实验测得的光谱数据相比较，结果比较一致。     

单层丝阵负载Z箍缩内爆辐射特性研究

在电流3—4MA的Angara-5-1脉冲装置上进行了单层钨丝阵Z箍缩实验,利用具有坪响应的X射线功率谱仪获得X射线功率,利用X射线纳秒分幅相机获得等离子体内爆辐射区图像.在丝阵直径相同时,实验得到较细的丝直径使得内爆较早,收缩比较大;较大的丝间隙使得内爆早期丝间等离子体不能有效的融合,而是较孤立的等离子体簇向内箍缩;较大的丝直径和丝间隙导致不稳定性波长较大.在丝阵直径不同,丝直径相当时,实验得到较大的丝阵直径内爆启动较早,具有较大的内爆速度,但等离子体在内爆过程中较分散.另外,较大的丝直径和丝阵直径使X射线辐射脉冲时间较宽.     

CoⅩⅧ离子2s~22p~53l2s2p~63l、2s~22p~54l组态的能级及跃迁波长计算

本文用相对论多组态Dirac-Fock广义平均能级(MCDF-EAL)模型,计算了可能形成超真空紫外区相干辐射的类氖等离子体激光工作物质的CoXVⅢ离子2s~22p~53l、2s2p~63l、2s~22p~54l组态精细结构能级的能量值,以及3l、4l-2p~6(~1S_0)、3l-3l＇、3l-4l＇、4l-4l＇多重态之间的跃迁波长值。3l、4l-2p~6(~1S_0)跃迁波长计算值与已知观测值符合相当好。     

类锂硅离子能级结构及软X射线激光光谱理论计算

本文采用Hartree-Fock自洽场方法,从理论上计算出类锂硅离子1s~2nl(n=2～7,l=0～5)各能级能量,并给出在极紫外(波长小于400(?))范围内各跃迁谱线的光谱性质、波长、振子强度和跃迁几率.对实验中已实现软X射线激光的跃迁(5d-3p,5f-3d,6d-3p,6f-3d),计算所得的跃迁波长与实验值完全相符.与现有文献的波长比较,相对误差不超过1%.     

Photoelectron branching ratio in the 5d subshell of Pt,Au and Pb measured with synchrotron radiation

The ratio in photoelectron intensity from the spin orbit split components in the 5d subshell has been measured for the metals Pt, Au and Pb using synchrotron radiation. For the core like Pb 5d states the ratio is found to deviate from the statistical value and exhibit an energy dependence that can be explained by atomic cross section models. For Pt and Au where the 5d electrons constitute valence band electrons a strong modulation of the branching ratio is observed, between about 80–200 eV, that we ascribe to “band structure effects”.     

Thermoelectric transport and spin density of graphene nanoribbons with Rashba spin–orbit interaction

In the present paper, we have theoretically investigated thermoelectric transport properties of armchair and zigzag graphene nanoribbons with Rashba spin–orbit interaction, as well as dephasing scattering processes by applying the nonequilibrium Green function method. Behaviors of electronic and thermal currents, as well as thermoelectric coefficients are studied. It is found that both electronic and thermal currents decrease, and thermoelectric properties been suppressed, with increasing strength of Rashba spin–orbit interaction. We have also studied spin split and spin density induced by Rashba spin–orbit interaction in the graphene nanoribbons.     

Measurement of a pauli and orbital paramagnetic state in bulk gold using x-ray magnetic circular dichroism spectroscopy

We show that bulk gold (Au) exhibits temperature-independent paramagnetism in an external magnetic field by x-ray magnetic circular dichroism spectroscopy at the Au L(2) and L(3) edges. Using the sum-rule analysis, we obtained a magnetic moment of 1.3 × 10(-4) μB/atom in an external magnetic field of 10 T and a paramagnetic susceptibility of 8.9 × 10(-6) for the 5d orbit. The induced paramagnetism in bulk Au is characterized by a large (≈ 30%) orbital contribution. This orbital component was retained even when Au atoms formed nanoparticles, playing an important role in stabilizing the spontaneous spin polarization in the Au nanoparticles.     

Spin–orbit scattering effect on electron–electron interactions in disordered metals

We have measured the low-temperature resistivities of a series of bulk crystalline disordered Ti_73−xAl₂₇Sn_x alloys (x≲5) as well as the sheet resistances of a number of thin ferromagnetic Ni films (≈120 Å thick) sandwiching an ultrathin Ag or Au (≲5 Å) layer. The level of impurities (concentration of Sn in the former case, and thickness of Ag or Au in the latter case) is progressively increased in order to enhance the spin–orbit scattering in a controllable manner. The influence of the spin–orbit scattering on the electron–electron interaction effects is studied from the temperature dependence of resistivities (sheet resistance) at low temperatures. We find that the electron–electron interaction contribution to the resistivities (sheet resistances) increases slightly with increasing spin–orbit scattering. Our observation is discussed in terms of the current theoretical concept for the electron–electron interactions in disordered metals.     

Spin–orbit coupling in low‐dimensional gold

We present experimental and theoretical evidence of the role played by the spin–orbit coupling in the electronic structure of a pseudomorphic Au monolayer on Nb(001) substrate. The bands found with the help of the angle‐resolved ultraviolet photoelectron spectroscopy (ARUPS) are compared with those obtained from ab initio self‐consistent calculations by the VASP and WIEN2k codes. The slab calculations are performed including geometric relaxation and using both the generalized‐gradient (GGA) and local‐density (LDA) approximations for the exchange–correlation energy. The dispersions and energy positions of the calculated bands agree with the experimentally determined band structure only if the LDA is used and the spin–orbit coupling is included. Therefore, both the structure relaxation and spin–orbit coupling are essential in understanding the electronic structure of the Au/Nb(001) system.

     

The 5f localization/delocalization in square and hexagonal americium monolayers: a FP-LAPW electronic structure study

The electronic and geometrical properties of bulk americium and square and hexagonal americium monolayers have been studied with the full-potential linearized augmented plane wave (FP-LAPW) method. The effects of several common approximations are examined: (1) non-spin polarization (NSP) vs. spin polarization (SP); (2) scalar-relativity (no spin-orbit coupling (NSO)) vs. full-relativity (i.e., with spin-orbit (SO) coupling included); (3) local-density approximation (LDA) vs. generalized-gradient approximation (GGA). Our results indicate that both spin polarization and spin orbit coupling play important roles in determining the geometrical and electronic properties of americium bulk and monolayers. A compression of both americium square and hexagonal monolayers compared to the americium bulk is also observed. In general, the LDA is found to underestimate the equilibrium lattice constant and give a larger total energy compared to the GGA calculations. While spin orbit coupling shows a similar effect on both square and hexagonal monolayer calculations regardless of the model, GGA versus LDA, an unusual spin polarization effect on both square and hexagonal monolayers is found in the LDA results as compared with the GGA results. The 5f delocalization transition of americium is employed to explain our observed unusual spin polarization effect. In addition, our results at the LDA level of theory indicate a possible 5f delocalization could happen in the americium surface within the same Am II (fcc crystal structure) phase, unlike the usually reported americium 5f delocalization which is associated with crystal structure change. The similarities and dissimilarities between the properties of an Am monolayer and a Pu monolayer are discussed in detail.     

Control of electron spin–orbit anisotropy in pyramidal InAs quantum dots

We investigate the electron spin–orbit interaction anisotropy of pyramidal InAs quantum dots using a fully three-dimensional Hamiltonian. The dependence of the spin–orbit interaction strength on the orientation of externally applied in-plane magnetic fields is consistent with recent experiments, and it can be explained from the interplay between Rashba and Dresselhaus spin–orbit terms in dots with asymmetric confinement. Based on this, we propose manipulating the dot composition and height as efficient means for controlling the spin–orbit anisotropy.     

Virtual bound states of Pd in Cu,Ag and Au and of Pt in Ag

The positions and widths of the virtual bound states of 5 and 10% Pd in Cu, Ag and Au and of 5 and 10% Pt in Ag have been measured by XPS. The spin—orbit splitting of the Pt state in Ag is reduced from the theoretical value, but comparable to the spectroscopic atomic value. The host lattice d-band structure is perturbed in the alloys.     

Dynamics and formation of vortices collapsed from ring dark solitons in a two-dimensional spin–orbit coupled Bose–Einstein condensate

We consider the dynamics and formation of vortices from ring dark solitons in a two-dimensional Bose–Einstein condensate with the Rashba spin–orbit coupling based on the time-dependent coupled Gross–Pitaevskii equation. Compared with previous results, the system exhibits complex dynamical behaviors in the presence of the spin–orbit coupling. With the modulation of the spin–orbit coupling, not only the lifetime of ring dark solitons is greatly prolonged, but also their attenuation kinetics is significantly affected. For two shallow ring dark solitons with the equal strength of the spin–orbit coupling, the radius of ring dark solitons increases to a maximum value over time and then shrinks into a minimum value. Due to the effect of the snake instability, ring dark solitons split into a series of ring-like clusters of vortex pairs, which perform complex oscillations. This indicates that the system is strongly dependent on the presence of the spin–orbit coupling. Furthermore, the effect of different initial modulation depths on the dynamics of ring dark solitons is investigated.     

Rapid collapse of spin waves in nonuniform phases of the second Landau level

The spin degree of freedom in quantum phases of the second Landau level is probed by resonant light scattering. The long wavelength spin wave, which monitors the degree of spin polarization, is at the Zeeman energy in the fully spin-polarized state at ν = 3. At lower filling factors, the intensity of the Zeeman mode collapses, indicating loss of polarization. A novel continuum of low-lying excitations emerges that dominates near ν = 8/3 and ν = 5/2. Resonant Rayleigh scattering reveals that quantum fluids for ν < 3 break up into robust domain structures. While the state at ν = 5/2 is considered to be fully polarized, these results reveal unprecedented roles for spin degrees of freedom.