Collisional excitation among the seven lowest states of TiXII

Collision strengths have been calculated for electron impact excitation of sodium-like TiXII for all 21 transitions amongst its lowest seven states. Configuration interaction wave functions have been used to represent the target states. The standard and no-exchangeR-matrix codes have been used to calculate the contribution of partial waves withL⩽8 andL>8 respectively. Collision strengths are tabulated at selected energies in the range 26 to 50 Ryd. Effective collision strengths are tabulated for electron temperatures in the range logT _e=4.0 to logT _e=6.0, withT _e in K. This is the first detailed calculation on this ion in which the effects of exchange, channel couplings and short-range correlation are taken into account.     

类氢He+、Li2+离子的电子碰撞强度的R矩阵计算

利用R矩阵方法计算了电子与He+离子碰撞的1s-2s和1s-2p跃迁的碰撞强度,结果表明包括10个靶态的计算可以得到精确的类氢离子的n=1→n=2各能级跃迁的碰撞强度,并首次利用R矩阵方法计算了电子与Li2+离子碰撞的1s-2s和1s-2p跃迁的碰撞强度.     

Spectroscopy and scattering matrices with nitrogen atom: Rydberg states and optical oscillator strengths

The scattering matrices of ${rm e}+ {rm N}^{+}$ with $J^pi=1.5^{+}$ in discrete energy regions are calculated using the eigenchannel R-matrix method. We obtain good parameters of multichannel quantum defect theory (MQDT) that vary smoothly as the function of the energy resulting from the analytical continuation property of the scattering matrices. By employing the MQDT, all discrete energy levels for N could be calculated accurately without missing anyone. The MQDT parameters (i.e., scattering matrices) can be calibrated with the available precise spectroscopy values. In this work, the optical oscillator strengths for the transition between the ground state and Rydberg series are obtained, which provide rich data for the diagnostic analysis of plasma.     

Observation of bands among the four lowest pseudorotational states of 1,3-dioxolane

The rotational transitions belonging to the pseudorotational bands n=0→1, n=2→3, and n=0→3 have been experimentally observed for 1,3-dioxolane in the spectral region of 153-364 GHz in a supersonic jet environment using the FASSST absorption spectrometer. Based on these observations, the symmetry ordering and the energy spacings of the four lowest states, n=0,1,2,3, have been established. The totality of the available data on this molecule, including those available from previously reported microwave studies has been analyzed, and a set of molecular constants has been obtained. Using the newly determined frequencies of the pseudorotational bands, along with the frequencies of the previously reported pseudorotational bands in the IR spectrum region, an empirical potential surface of 1,3-dioxolane has been obtained. The results of this analysis are compared to the potential surface and rotational constants obtained from quantum chemistry calculations.     

类铍离子N3+激发态的能量、振子强度和跃迁几率

利用多组态相互作用方法及Rayleigh-Ritz变分法,计算了类铍N3+ 基态(1s22s21S)和三个激发态(1s22s2p1P0, 1s22s2p3 P0, 1s22p23P)的能量,运用截断变分方法得到能量的改进量,包括了相对论能量和质量极化效应.计算了相关态的振子强度和辐射跃迁率.计算结果与其它理论和实验结果符合得很好.     

Non-Markovianity in the presence of multiple thermal environments via collision model

By means of the collision model, we study the non-Markovianity of an open quantum system S being coupled to M thermal reservoirs. In our model, each reservoir is modeled as a chain of ancillas whose intracollisions account for the occurrence of non-Markovian dynamics. We show that by incorporating M reservoir ancillas into the system, the non-Markovian dynamics of S can be embedded in the extended system that experiences a completely Markovian dynamics. The number M of involved reservoirs can thus be identified as the memory depth and determines the degree of the non-Markovianity. In the equilibrium case with identical temperatures for all the reservoirs, we show that though the non-Markovianity is proportional to M in the zero and relatively low temperature regimes, in the relatively high temperature regime such proportional relation holds only for the weak intracollisions of the reservoir ancillas. In the nonequilibrium situation, we examine the effect of temperature difference of reservoirs on the non-Markovianity. Focusing on a simple situation with two reservoirs, we observe that the nonzero temperature difference has a significant impact on the non-Markovianity.     

Theoretical study of the transition probabilities among the three lowest electronic states of the SeS molecule

Spin-perturbed CI wavefunctions are reported for the X ³Σ^? electronic states of the SeS molecule. The Breit-Pauli approach is employed using the one- and two-electron spin-orbit operator as the perturbing hamiltonian and a zeroeth-order basis of CI eigenfunctions generated by the standard multireference single- and double-excitation (MRD-CI) formalism. Transition moments are reported between each of the above states for electric and magnetic dipole and electric quadrupole radiative processes, and these results are compared with recent experimental high resolution data obtained by Fink, Kruse, Ramsay and Wang. Generally good agreement is found between computed and observed ratios of such quantities, but the absolute values of the computed transition moments are uniformly found to be only somewhat less than half as large as the corresponding observed results. A simple formula is presented which relates the magnetic moments of the b ¹Σ⁺-X ³Σ1? transitions to twice the square root of the ratio of two observable energy differences and this result promises to be useful in future experimental studies attempting to estimate line strengths for this type of band system. On this basis arguments are also presented supporting the view that the computed absolute intensities may be more accurate than would appear from the original experimental assessment of the SeS spectroscopic data.     

Non-equilibrium steady-states of memoryless quantum collision models

We investigate the steady state properties arising from the open system dynamics described by a memoryless (Markovian) quantum collision model, corresponding to a master equation in the ultra-strong coupling regime. By carefully assessing the work cost of switching on and off the system-environment interaction, we show that only a coupling Hamiltonian in the energy-preserving form drives the system to thermal equilibrium, while any other interaction leads to non-equilibrium steady states that are supported by steady-state currents. These currents provide a neat exemplification of the housekeeping work and heat. Furthermore, we characterize the specific form of system-environment interaction that drives the system to a steady-state exhibiting coherence in the energy eigenbasis, thus, giving rise to families of states that are non-passive.     

里德堡钠原子抗磁谱的模型势计算

用B样条基组展开方法结合模型势计算了里德堡钠原子抗磁谱和相应的振子强度谱.径向和角向均采用高阶B样条基组.计算结果与已有的R-矩阵和多通道量子亏损理论相结合(R-matrix MQDT)法及其他理论计算结果作了比较,几种理论结果在我们所研究的能区内符合得非常好.本文方法较R-ma-trix MQDT法简单,易于推广到交叉电磁场中里德堡原子的精确谱的计算中.     

Photoionization of the ground1 S e and twenty lowest excited states of the Ne-like Fe16+

TheR-matrix method is used to calculate cross-sections for the photoionization of Ne-like Fe¹⁶⁺ from ground 2s ²2p ⁶¹ S ^e and excited states belonging to 2s2p ⁶ 3l and 2s ²2p ⁵ 3l configurations. Configuration interaction wavefunctions are used to represent two target states of Fe¹⁷⁺ ion retained in theR-matrix expansion. The cross-sections are obtained as a function of kinetic energy (ε _k) of the ejected electron from 10 to 24 Ry. For low kinetic energy the cross-sections show series of Rydberg states which converge onto² S ^e threshold Fe¹⁷⁺. The calculations are carried out in the LS coupling.     

Graphite dislocations induced by collision of neutral mercury droplets

High speed neutral clusters and mercury droplets from a gas jet impactor are allowed to collide with graphite surfaces. These collisions produce a variety of dislocations. One of the dislocations is a narrow dislocation band with atomic resolution. This band has two partial dislocations on the sides of a central region of abc structure.     

Relativistic RRR-matrix studies of photoionization processes of Ar~(5+)

The 3s–np photoionization processes of the ground state 2P1/2 and the metastable state 2P3/2 of Ar5+ are investigated using our recently developed relativistic R-matrix code, where the interactions between the bound states and the continuum states are included. Both resonance positions and the oscillator strengths are in much better agreement with the absolute experimental measurements by Wang et al. [Wang J C, Lu M, Esteves D, Habibi M, Alna'washi G and Phaneuf R A 2007 Phys. Rev. A 75 062712] with a resolution of 80 meV than their theoretical results. The contributions of the two experimental unresolved transitions are distinguished in our calculations, which show that the transitions from the ground state also make significant contributions to some resonances. Our theoretical results are also in good agreement with the measurements for the first resonance with a higher resolution of 20 meV.     

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采用流体动力学模型研究了离子与中性粒子的电荷交换碰撞效应对直流偏压鞘层厚度的影响。对于平板鞘层,结果表明随着碰撞参数的增大,鞘层厚度明显地变小。根据数值结果,给出了碰撞情况下的Child-Lang-muir定律的拟合式。研究了柱形和球形靶的靶半径对鞘层厚度的影响。     

Electron impact excitation of Ni XIX using theR-matrix method

Collision strengths for all the transitions between the 15 lowest states of neon-like Ni XIX have been calculated for electron impact in the 80–140 Ry energy range. Configuration-interaction wavefunctions have been used to represent the target states. The standardR-matrix code has been used to calculate the lower scattering partial waves (L≤9), while a no-exchange version of the same code has been used to compute efficiently the higher partial waves (L≥10). Effective collision strengths for 105 excitation transitions between the ground state 2s ²2p ^{6 1} S ^e and the 142s ²2p ⁵3l Rydberg states are tabulated for electron temperatures in the range logT=5.40 to logT=7.00, withT expressed in °K.     

Non-Fermi-liquid behavior of compressible electron states on the lowest Landau level

Experiments show that at even denominator fractions (EDF) (7p = 1=2;3=4;3=2,...) the two-dimensional electron gas (2DEG) in a strong magnetic field becomes compressible, has no energy gap, and demonstrates the presence of an ostensible Fermi surface (FS). Since this phenomenon results from a minimization of the interaction, rather than the kinetic energy, the EDF states might well exhibit deviations from a conventional Fermi liquid (FL). We show that impurity scattering and its interference with electronelectron and electron-phonon interactions provide examples of intrinsically non-Fermi-liquid (NFL) transport at EDFs.     

Fast elliptic solvers in cylindrical coordinates and the Coulomb collision operator

In this paper, we describe a new class of fast solvers for separable elliptic partial differential equations in cylindrical coordinates (r, θ, z) with free-space radiation conditions. By combining integral equation methods in the radial variable r with Fourier methods in θ and z, we show that high-order accuracy can be achieved in both the governing potential and its derivatives. A weak singularity arises in the Fourier transform with respect to z that is handled with special purpose quadratures. We show how these solvers can be applied to the evaluation of the Coulomb collision operator in kinetic models of ionized gases.