Electron rescattering in strong-field photodetachment ofF−

Abstract

We present ab initio studies of photoelectron spectra for above threshold detachment (ATD) of F − anions in short, 1300 nm and 1800 nm laser pulses. We identify and assess the importance of electron rescattering in strong-field photodetachment of a negative ion through comparison with an analytic, Keldysh-type approach, demonstrating the capability of ab-initio computation in the challenging near-IR regime. We further assess the influence of the strong electron correlation on the photodetachment.PACS numbers: 32.80.Gc 31.15.VElectron rescattering is one of the fundamental processes occuring in the interaction between matter and intense light fields [1]. The mechanism is a critical part of the well known three-step or recollision model for high harmonic generation (HHG) or strong field double ionisation. According to the model an electron is first ionised, then driven by a strong laser field, before recolliding with the parent ion, either recombining, leading to HHG [2,3], or rescattering, leading to high-energy electron emission [4,5], or non-sequential double ionisation [6].Electron rescattering also encodes structural information about the residual ion into the wavepacket of the ejected electron and can thus be exploited as an experimental probe of the structure of the parent ion [1]. The technique is especially sensitive as the current density of a recolliding electron wavepacket exceeds that of conventional electron sources by several orders of magnitude [7]. Furthermore, the inherently subcycle and phase-locked nature of the recollision process gives access to electron dynamics on the attosecond scale, via information embedded in the photoelectron spectrum [8,9].One of the open questions in strong-field science concerns the importance of electron rescattering for negative ions. Significant progress has been made in understanding and controlling the equivalent process in neutral atoms and positive ions [10], but above-threshold detachment (ATD) presents a different challenge. The small binding energy allows detachment at low intensities. Hence to reach significant recollision energies, nearinfrared (NIR) laser fields are required. In addition, the absence of the Coulomb potential makes it easier for the electron wavepacket to spread out, reducing the effect of rescattering [4,5]. While evidence for rescattering from negative ions has been found experimentally [11], no verification has yet been provided from ab initio theory. A theoretical approach, based on first order correction to the strong field approximation, was able to reproduce experimental results from Br − and F − , [12] but a more recent study, using a numerical solution of the time-dependent Schrödinger equation (TDSE), found "no qualitative evidence of rescattering" for H − [13]. In this report we demonstrate that ab-initio theory can be used to investigate rescattering in the NIR regime.An additional complication in the description of negative ions is the much larger influence of dielectronicrepulsion. Several approximate methods have been empl...

Electron rotational asymmetry in strong-field photodetachment from F− by circularly polarized laser pulses

“…The RMT method has been used to analyze strong-field dynamics of a variety of atoms and ions [45][46][47], and has recently been extended to handle light fields of arbitrary polarization [48]. A recent RMT study [49], investigated above-threshold detachment and electron rescattering in the F − negative ion, driven by long-wavelength (1300 nm and 1800 nm), ultrashort laser pulses. Comparison with a Keldysh-type approach [50] highlighted the role of short-range multielectron correlations, and underlined the need for manybody, quantum-dynamic simulations to obtain reliable photoelectron spectra.…”

“…More generally, electron detachment from negative ions is of considerable interest, since their structure, and laserdriven dynamics, are significantly influenced by multielectron correlations. Various techniques have been used to treat photodetachment from negative ions [49][50][51][52][53][54][55][56][57], where electron repulsion is handled approximately. Negative ions are particularly amenable to investigation by methods based on the strong-field approximation (SFA) [55], since their neutral core dictates that the detachment dynamics is influenced by short-range interactions alone.…”

Time-dependent restricted-active-space self-consistent-field theory with space partition

“…Soon after, the R-matrix theory including time dependence (RMT) [25][26][27][28] was proposed based on the same SP concept with the Bloch operator [29] formalism but directly treating the wave function without the R matrix. The Arnoldi Lanczos scheme [30,31] is exploited in RMT to execute the time propagation more efficiently than in TDRM, and has successfully led to various applications [32][33][34][35][36][37][38]. The TD restricted-and generalized-active-space configurationinteraction [TD-(RAS/GAS)CI] approach [39][40][41] follows the same SP strategy, and is similar to RMT but based on the finite-element discrete-variable-representation (FEDVR) functions (see, e.g., Ref.…”

Multielectron effects in strong-field ionization of CO2 : Impact on differential photoelectron spectra

“…The application of these methods to computation of photoelectron spectra in the long wavelength regime has however been minimal so far. Spectra for atoms, using a multielectron theory, have only been recently reported using the R-matrix method [22] and the hybrid anti-symmetrized coupled channels (haCC) method [13]. In the case of molecules, the increased cost of computations resulting from reduced symmetry, have rendered such computations infeasible so far.…”