The beginning of the application of the method of interacting configurations in the complex number representation to the compound atomic systems has been presented. The spectroscopic characteristics of the Be atom in the problem of the electron-impact ionization of this atom are investigated. The energies and the widths of the lowest autoionizing states of Be atom are calculated.
Using TRIUMF's off-line laser ion source test stand with a system of tunable titanium sapphire lasers, the polarization dependence of laser resonance ionization has been investigated using beryllium. A significant polarization dependence was observed for the excitation path $^1$S$_0$$\rightarrow$$^1$P$^{\circ}_1$$\rightarrow$$^1$S$_0$, which are typical transitions for alkaline and alkaline-like elements. This polarization dependence was further verified on Be radioactive isotopes at TRIUMF's isotope separator and accelerator facility (ISAC). Laser polarization was proven to be an important pa…
Calculations for electron-impact ionization of magnesium and calcium atoms in the method of interacting configurations in the complex number representation
The experimental thermonuclear reactor, ITER, is currently being constructed in Cadarache, France. The reactor vessel will be constructred with a beryllium coated wall, and a tungsten coated divertor. As a plasma-facing component, the divertor will be under conditions of extreme temperature, resulting in the sputtering of tungsten impurities into the main body plasma. Modelling and understanding the potential cooling effects of these impurities requires detailed collisional-radiative modelling. These models require a wealth of atomic data for the various atomic species in the plasma. In partic…
Interplay between relativistic energy corrections and resonant excitations in x-ray multiphoton ionization dynamics of Xe atoms
本文从理论上研究了重原子的X射线多光子电离动力学。当原子暴露于由X射线自由电子激光（XFEL）产生的强X射线脉冲时，它通过一系列单光子电离和伴随的弛豫过程电离成高电荷离子，并且其最终电荷状态受到可以通过单光子电离电离的最后离子状态的限制。如果X射线多光子电离涉及重原子中的深内壳层电子，则相对论效应引起的能量移动在电离动力学中起重要作用，如[Phys.\修订版本\ Lett. \textbf{110}，173005（2013）]。另一方面，如果X射线束具有宽的能量带宽，则高强度X射线脉冲可以驱动宽范围的离子状态的共振光激发，并且甚至超过直接单光子电离极限，如在[Nature\ Photon.]中首次提出的。\textbf{6}，858（2012）]。为了研究相对论和共振效应，我们扩展了\textsc{xatom}工具包，将相对论能量校正和共振激发在X射线多光子电离动力学计算。计算了光子能量分别为1.5keV和5.5keV的强流XFEL脉冲与双原子相互作用系统的电荷态分布。对于这两种光子能量，我们证明了共振激发的电离动力学的作用是改变由于轨道能级的相对论效应的显着移位。因此，要准确模拟高X射线强度下的多光子多重电离动力学，必须考虑这两种效应。
A practical theoretical formalism for atomic multielectron processes: direct multiple ionization by a single Auger decay or by impact of a single electron or photon
We study a novel regime of the Rydberg excitation blockade using highly Stark-shifted, yet long-living, states of Rb atoms subject to electric fields above the classical ionization limit. Such states allow tuning the dipole-dipole interaction strength while their ionization rate can be changed over two orders of magnitude by small variations of the electric field. We demonstrate laser excitation of the interacting Rydberg states followed by their detection using controlled ionization and magnified imaging with high spatial and temporal resolution. Our work reveals the hitherto unexplored possi…
A minority relativistic electron component can arise in both laboratory and naturally-occurring plasmas. In the presence of high-atomic-number ion species, the ion charge state distribution at low bulk electron temperature can be dominated by relativistic electrons, even though their density is orders of magnitude lower. This is due to the relativistic enhancement of the collisional excitation and ionization cross sections. The resulting charge state effect can dramatically impact the radiative power loss rate and the related Bethe stopping power of relativistic electrons in a dilute plasma.
Strong field processes in the non-relativistic regime are insensitive to the electron spin, i.e. the observables appear to be independent of this electron property. This does not have to be the case for several active electrons where Pauli principle may affect the their dynamics. We exemplify this statement studying model atoms with three active electrons interacting with strong pulsed radiation, using an ab-initio time-dependent Schrödinger equation on a grid. In our restricted dimensionality model we are able, for the first time, to analyse momenta correlations of the three outgoing electron…
Ionization of atoms by slow heavy particles, including dark matter
在慢重粒子与束缚电子的散射过程中，原子和分子会发生电离，这种涉及亲轻子的大质量弱相互作用粒子（WIMPs）的相互作用是DAMA暗物质直接探测实验中异常的9 σ年调制现象的一个有希望的可能解释[R. Bernabei等人，EUR. J. C 73，2648（2013）]。我们证明了这种相互作用的玻恩近似的适用性，通过显示其等效的半经典绝热处理慢移动的WIMPs的原子电离。传统观点认为，这样一个过程的电离概率应该是指数级的小。然而，我们发现，由于非解析，尖状行为的库仑函数靠近核这种抑制被删除，导致有效的原子结构增强。至关重要的是，我们还表明电子相对论效应实际上对这样的过程做出了主要贡献，将微分截面增强了1000倍。
We develop and test a method that integrates many-electron weak-field asymptotic theory (ME-WFAT) [Phys. Rev. A 89, 013421 (2014)] in the integral representation (IR) into the density functional theory (DFT) framework. In particular, we present modifications of the integral formula in the IR ME-WFAT to incorporate the potential terms unique to DFT. By solving an adiabatic rate equation for the angle-resolved ionization yield in our DFT-based ME-WFAT method, we show that the results are in excellent agreement with those of real-time time-dependent density functional theory (RT-TDDFT) simulation…
The dipole blockade effect at laser excitation of mesoscopic ensembles of Rydberg atoms lies in the fact that the excitation of one atom to a Rydberg state blocks the excitation of other atoms due to the shift in the collective energy levels of interacting Rydberg atoms. It is used to obtain the entangled qubit states based on single neutral atoms in optical traps. In this paper, we present our experimental results on the observation of the dipole blockade for mesoscopic ensembles of 1-5 atoms when they are detected by the selective field ionization method. We investigated the spectra of the t…
An Efficient and Accurate Grid Method for Solving the Time-Dependent Schroedinger Equation: Application of Coulomb Wave Function DVR to Atomic Systems in Strong Laser Fields
RMT is a program which solves the time-dependent Schrodinger equation for general, multielectron atoms, ions and molecules interacting with laser light. As such it can be used to model ionization (single-photon, multi-photon and strong-field), recollision (high-harmonic generation, strong-field rescattering), and more generally absorption or scattering processes with a full account of the multielectron correlation effects in a time-dependent manner. Calculations can be performed for targets interacting with ultrashort, intense laser pulses of long-wavelength and arbitrary polarization. Calcula…
