报告题目：Two-electron angular patterns in sequential double ionization of neon
报告人：Lampros Nikolopoulos，Dublin City University
报告时间：2014年7月3日（星期四）10:15
报告地点：理学院会议室（理-352）
报告内容：
Recently, the angular correlations of the two-electrons in sequential two-photon double ioniza-tion of noble gases by a linearly polarized field, has attracted considerable theoretical and exper-imental attention. More specifically, the photoionization of neutral neon｜1s22s22p6;1S0〉by an UV field, promotes, predominantly, one bound electron from the valence shell (2p) to a continuum state with the residual ion (Ne1+) left in one of the spin-orbit doublet〡1s22s22p5;2P3/2,1/2〉states. The production of singly-charged ions may be followed by further ionization leading to the ejection of yet another electron from the same valence shell. The dominant ionization pathways are determined by simple energy and angular conservation arguments and consist of the four ionic states ｜1s22s22p4;1S0〉, ｜1s22s22p4;1D0〉,｜1s22s22p4;3P0,1,2〉plus the two ejected electrons.
In this talk, I'll present a time-dependent density matrix approach to calculate the alignment dependence of the intermediate Ne1+ states on the pulse properties such as duration and intensity. We have found that considerable dynamic ion alignment is present when the field duration is comparable with the precession time of the spin-orbit doublet Ne+(2P1/2)-Ne+(2P3/2) which is around 41 fs. The magnitude of the dynamic alignment becomes larger as the field becomes stronger. Accordingly, the pulse duration affects the angular patterns of the ejected electrons in double ionization events. The change of the two-electron angular distributions with the pulse duration is particularly evident for the Ne2+(3P) residual ion.
报告人简介
Dr Lampros Nikolopoulo's research area of interest is the Theoretical Atomic and Optical Physics with emphasis in ab-initio computation of strong laser-atom/molecules interactions. Dr Nikolopoulos got his PhD in Univ. of Crete (Physics), Greece and his research carreer include posts in Max-Planck Institute for Quantum Optics (MPQ), Univ of Aarhus Denmark and Queen's Univ. of Belfast, UK, while since 2009 holds a Lecturer position in Dublin City University (Ireland) at the School of Physical Sciences. A particular feature of his research in atomic/molecular physics is in developing and implementing high-performance computational algorithms for the calculation of complex atomic and molecular structures and the direct solution of the time-dependent Schrodinger Equation (TDSE) of complex structures in strong laser fields. Most recently Dr Nikolopoulos has also focused on the development of computational codes using general-purpose graphics processing cards (GPGPU). His collaborations over the year include theoretical and experimental groups worldwide on areas such as ultrafast multiphoton processes, atomic structure calculations, time-dependent R-matrix methods, stochastic differential equations as well as the metrology and characterization of attosecond pulses and free-electron laser studies).
