Regular series of doubly excited states inside two-electron continua: Application to2s2-hole states in neon above the Ne2+ 

Abstract

We report results of many-electron calculations that predict the presence of a regular series of autoionizing doubly excited states (DESs) of 1 P o symmetry embedded inside one-as well as two-electron continua of neon, in the range of excitation 105.9-121.9 eV above the ground state. The limit of 121.9 eV represents the two-electron ionization threshold (TEIT) labeled by Ne 2+ 1s 2 2p 6 1 S. The wave functions of these unstable states and their properties are computed according to the theoretical framework, which is explained and justified in the text. Their formal structure is (ψ core ) 1 S ⊗ ( r 1 , r 2 ) 1 P o , where both ψ core and ( r 1 , r 2 ) are correlated wave functions, the latter being represented reasonably accurately by a self-consistently obtained superposition of nsnp and np(n + 1)d configurations n = 3-7. By fitting the calculated lowest energies at each value of n, (five states), an effective hydrogenic formula is obtained, which gives the whole energy spectrum up to the TEIT. The autoionization widths are small and decrease with excitation energy. Oscillator strengths for the excitation of these narrow resonance states by absorption of one photon are also small. Because of their electronic structure, these states are compared to 1 P o DESs in He, which were found in the 1980s to constitute a regular ladder with wave-function characteristics that tend to those of the so-called Wannier state at threshold. In the present case, the presence of the core and the concomitant interactions do not permit the emergence of such geometrical features.

Time delays for attosecond streaking in photoionization of neon

“…The second model included pseudostates to account for the polarization of the residual ion by the outgoing photoelectron. We note that the model with 38 target states also accurately represents the series of 2s 2 -hole doubly excited states that have been previously discussed by Komninos et al [31]. These resonances are long-lived (> 100 fs) and thus narrow, and have small dipole transition probabilities from the ground state.…”

Attosecond-Resolved Electron Dynamics in Many-Electron Atoms: Quantitative Theory and Comparison with Measurements

“…Only a description of the essentials is given here. The main purpose is to point out that the experimental findings on helium [7,8] and neon [10,11] are in agreement with our theoretical results of 2007 [16] and 2010 [11] (see also the conclusion of [17]). Complete information can be found in the original publications [7,8,10,11,16], including the supporting online material of [11].…”

“…In recent publications by Kaldun and Blättermann et al [7,8], by Krausz [9], and by Isinger et al [10], there is discussion and presentation of results of new experiments on time-resolved hyperfast electron dynamics in many-electron systems, made possible through the application of modern techniques of spectroscopy with attosecond resolution. These measurements and the corresponding implications are directly related to, and in harmony with, our proposals and theoretical results that were produced in the '00s, based on time-dependent formalisms that allow the practical use of many-electron wavefunctions [1][2][3][4][5][6][11][12][13][14][15][16][17]. In the following paragraphs, I recall how these compare with the results and discussions in [7][8][9][10][11].…”

“…The second part, Sections 4-6, points to experimental findings and corresponding discussions concerning prototypical ultrafast electronic processes and phenomena in N-electron atoms [7][8][9][10][11] and compares them to results and discussions by the Athens team published from 1996 to 2011 [1][2][3][4][11][12][13][14][15][16][17]. Papers [7][8][9][10][11][12][13][14][15][16][17] have to do with the quantitative understanding and the possibility of credible prediction of the time-dependent many-electron physics of attosecond-resolved electron rearrangements in many-electron systems.…”

Attosecond photoionization dynamics in neon

“…In particular, the experimental measurement of the timedelay in Ne between the photoemission of electrons from the 2s and 2p shells [18] has provoked a lot of interest due to a disagreement in the magnitude of the measured and calculated time-delays, see, e.g., Refs. [26][27][28][29][30][31][32][33][34][35]. Note that very recently, analysis of interferometric measurements [36] suggests that a shake-up process, not resolved and accounted for in the streaking experiment of Ref.…”