超快强激光驱动的原子分子电离

强场电离是超快强激光与物质相互作用时发生的基本物理过程。强场驱动原子分子的电离电子动力学过程发生在一个光学振荡周期以内,是在阿秒时间尺度上研究电子超快动力学的典范。不仅如此,强场驱动下的超短电子束还为探测原子分子的结构及其超快动力学提供了重要的技术手段。文章首先简要阐述了超快强光场中原子分子电离的基本物理图像,在此基础上,介绍了近年来基于强场电离电子开展的超快过程研究的几个例子,最后简要讨论了强场电离研究的未来可能发展方向。     

Scaled-energy spectroscopy of a ｜M｜= 1 Rydberg barium atom in an electric field

We observe strong energy-dependent quantum defects in the scaled-energy Stark spectra for |M| = 1 Rydberg states of barium atoms at three scaled energies: ε = 2.000,ε = 2.500 and ε = 3.000.In an attempt to explain the observations,theoretical calculations of closed orbit theory based on a model potential including core effect are performed for non-hydrogenic atoms.While such a potential has been uniformly successful for alkali atoms with a single valence electron,it fails to match experimental results for barium atoms in the 6snp Rydberg states with two valence electrons.Our study points out that this discrepancy is due to the strong perturbation from the 5d8p state,which voids the simple approximation for constant quantum defects of principle quantum number n.     

Sr原子|M|=1电场标度能谱

通过同步改变激光扫描波长和外加电场大小,保持标度能为常量,将Sr原子从基态激发到|M|=1的激发态,得到了标度能ε=-3.00,-2.50,-1.88时的常数标度能谱.实验傅里叶变换回归谱与氢原子闭合轨道理论计算进行了比较,峰值位置符合较好,峰值强度则受Sr原子实效应影响较大.     

The Coulomb effect on a low-energy structure in above-threshold ionization spectra induced by mid-infrared laser pulses

We investigate the low-energy structure(LES)in the above-threshold ionization spectrum at a mid-infrared laser wavelength with a semiclassical model.Using a softened Coulomb potential(CP)and changing the softening parameter,we show that though the very low-energy structure(VLES)and high low-energy structure(HLES)are both due to the interaction between the ionic CP and the electron,the two structures have different physical mechanisms:the VLES can be attributed to the electron–ion Coulomb interaction at a rather small distance and the HLES is more likely to be ascribed to the electron–ion Coulomb interaction at a large distance.     

Stability of Complex-Rotation Method on a Simple Resonant Scattering Problem

The stability of the complex-rotation method in B-spline basis for a simple atomic resonant scattering problem in free field is investigated. The numerical calculation shows that this method has a feature that the solution will not change in a wide range of rotation angle θ. Our determined scattering resonant energies and widths exactly coincide with the popularly accepted values. A new resonance is identified numerically although it is very broad. The norm of the complex eigenvalue, ｜E｜, is proposed to investigate and to evaluate the stability of the obtained complex eigenvalues.     

Extreme Ultraviolet Frequency Comb with More than 100μW Average Power below 100nm

Extreme ultraviolet(XUV) frequency comb is a powerful tool in precision measurement.It also brings many new opportunities to the field of strong field physics since high harmonic generation related phenomena can be studied with high repetition rate.We demonstrate the generation of an XUV frequency comb with the aid of intra-cavity high harmonic generation process.The setup is driven by a high power infrared frequency comb, and an average power of 4.5 kW is reached in the femtosecond enhancement ...     

Photodetachment of H- near an elastic surface in a magnetic field

This paper investigates the photodetachment of the negative hydrogen ion H near an elastic wall in a magnetic field.The magnetic field confines the perpendicular motion of the electron,which results in a real three-dimensional well for the detached electron.The analytical formulas for the cross section of the photodetachment in the threedimensional quantum well are derived based on both the quantum approach and closed-orbit theory.The magnetic field and the elastic surface lead to two completely different modulations to the cross section of the photodetachment.The oscillation amplitude depends on the strength of the magnetic field,the ion-wall distance and the photon polarization as well.Specially,for the circularly polarized photon-induced photodetachment,the cross sections display a suppressed(E E th) 1/2 threshold law with energy E in the vicinity above Landau energy E th,contrasting with the(E E th) 1/2 threshold law in the presence of only the magnetic field.The semiclassical calculation fits the quantum result quite well,although there are still small deviations.The difference is attributed to the failure of semiclassical mechanics.     

非共振相互作用系统中密度算符间距的演化

考虑到失谐量和原子初始相干性,给出了任意初态分布的二能级原子与任意单模场相互作用的密度算符间距的一般表达式.着重讨论了一个任意态分布的二能级原子与相干态光场相互作用时失谐量对密度算符间距演化的影响.结果表明：密度算符间距明显地依赖于失谐量的取值. 关键词：     

Sr原子|M|=1电场标度能谱

通过同步改变激光扫描波长和外加电场大小,保持标度能为常量,将Sr原子从基态激发到|M|=1的激发态,得到了标度能ε=-3.00,-2.50,-1.88时的常数标度能谱.实验傅里叶变换回归谱与氢原子闭合轨道理论计算进行了比较,峰值位置符合较好,峰值强度则受Sr原子实效应影响较大.     

Universality of the Dynamic Characteristic Relationship of Electron Correlation in the Two-Photon Double Ionization Process of a Helium-Like System

Universality of the dynamic characteristic relationship between the characteristic time t_c and the two-electron Coulomb interaction energy ■ of the ground state in the two-photon double ionization process is investigated via changing the parameters of the two-electron atomic system and the corresponding laser conditions.The numerical results show that the product ■ keeps constant around 4.1 in the cases of changing the nucleus charge,the electron charge,the electron mass,and changing ...