Nonsequential double ionization below laser-intensity threshold: Anticorrelation of electrons without excitation of parent ion

Abstract

Two-electron correlated spectra of non-sequential double ionization below laser-intensity threshold are known to exhibit back-to-back scattering of the electrons, viz., the anticorrelation of the electrons. Currently, the widely accepted interpretation of the anticorrelation is recollision-induced excitation of the ion plus subsequent field ionization of the second electron. We argue that another mechanism, namely simultaneous electron emission, when the time of return of the rescattered electron is equal to the time of liberation of the bounded electron (the ion has no time for excitation), can also explain the anticorrelation of the electrons in the deep below laser-intensity threshold regime. Our conclusion is based on the results of the numerical solution of the time-dependent Schrödinger equation for a model system of two one-dimensional electrons as well as an adiabatic analytic model that allows for a closed-form solution.

Strong-field nonsequential double ionization of Ar and Ne

“…The ejection of two low-energy electrons in opposite directions was viewed as analogous to the Wannier threshold phenomenon in electron-impact ionization [31]. Meanwhile, Bondar et al [32] have addressed model atoms where the two electrons can emerge with two anticorrelated momenta, but its relevance to NSDI is less clear since they model the target atom by using a short-range potential supporting only one bound state.…”

Role of high ponderomotive energy in laser-induced nonsequential double ionization

“…This especially relates to RESI. Several theoretical models have been proposed to explain the general features of RESI [13,[15][16][17][18][19], however, no clear conclusion exists about the role of Coulomb effects, depletion of the excited state, and on excitation channels. When considering results obtained using ultrashort pulses, the pattern is largely defined by depletion effects [20][21][22], contributions of doubly excited states [23], soft recollisions [24], and quantum interferences of different excitation channels [25].…”

Slingshot Nonsequential Double Ionization as a Gate to Anticorrelated Two-Electron Escape

“…This pattern was found to prevail, but not substantially, over correlated two-electron escape. It was observed in NSDI of several atoms driven by intense (strongly-driven) long duration pulses [24][25][26][27][28][29][30][31]. Multiple re-collisions, in the context of RESI, were put forth to explain anti-correlated two-electron escape [24][25][26][27][28].…”

“…Multiple re-collisions, in the context of RESI, were put forth to explain anti-correlated two-electron escape [24][25][26][27][28]. Electron-electron repulsion was also suggested as a possible explanation [30,31].…”