Weak-field asymptotic theory of tunneling ionization: benchmark analytical results for two-electron atoms

Abstract

The recently developed many-electron weak-field asymptotic theory of tunneling ionization of atoms and molecules in an external static electric field (Tolstikhin et al 2014, Phys. Rev. A 89, 013421) is extended to the first-order terms in the asymptotic expansion in field. To highlight the results, here we present a simple analytical formula giving the rate of tunneling ionization of two-electron atoms H− and He. Comparison with fully-correlated ab initio calculations available for these systems shows that the first-order theory works quantitatively in a wide range of fields up to the onset of over-the-barrier ionization and hence is expected to find numerous applications in strong-field physics.

Transverse electron momentum distribution in tunneling and over the barrier ionization by laser pulses with varying ellipticity

“…We also note that the Keldysh theory [5] and its subsequent developments and generalizations [10][11][12][13] describe the quasistatic limit of small laser pulse frequencies. In strict terms, the Keldysh approach provides a leading-order term in the asymptotic expansion of the ionization rate, a systematic way to obtain higher order terms is described in [14,15].…”

First-order correction terms in the weak-field asymptotic theory of tunneling ionization in many-electron systems

“…In this case, accurate electronic structure calculations are feasible and the theory can be implemented as prescribed, without any additional approximations. In [18], we have considered tunneling ionization processes H − (1s 2 1 S)  H 0, 0, 0 ( ), He(1s 2 1 S)  + He 0, 0, 0 ( ), He(1s 2 1 S)  + He 1, 0, 0 ( ), and He(1s 2 1 S)  + He 0, 1, 0 ( ). In all the cases, the initial twoelectron system is in the ground state and the final state of the parent one-electron subsystem is identified by parabolic quantum numbers n n m , ,…”

“…Here we make the next step, namely, we combine the achievements of [15] and [17] by deriving the first-order terms within the ME-WFAT. The resulting theory was highlighted in [18] by demonstrating its performance for two-electron atoms, in which case accurate ab initio results are available for comparison. In the present paper we document the derivation omitted in [18] and provide additional numerical illustrations.…”

Static-field ionization model of He-like ions for diagnostics of light-field intensity

“…When the field intensity is sufficiently weak, the weak-field asymptotic theory (WFAT) [20] provides a rigorous expansion of the pre-exponential factor in the tunneling rate in powers of the field strength. The WFAT has been extended to many-electron systems [21][22][23][24] and has been applied to molecular ionization [25,26]. In [24], the WFAT was applied to He-like ions for an arbitrary value of the nuclear charge number Z.…”