Near-threshold photoelectron holography beyond the strong-field approximation

Abstract

We study photoelectron angular distributions (PADs) near the ionization threshold with a newly developed Coulomb quantum-orbit strong-field approximation (CQSFA) theory. The CQSFA simulations exhibit an excellent agreement with the result from the time-dependent Schrödinger equation. We show that the low-energy fan-shaped pattern in the PADs corresponds to a subcycle time-resolved holographic structure and stems from the significant influence of the Coulomb potential on the phase of the forward-scattered electron trajectories, which affects different momenta and scattering angles unequally. Our work provides a direct explanation of how the fan-shaped structure is formed, based on the quantum interference of direct and forward-scattered orbits. Moreover, our work shows that the fan-shaped pattern can be used to extract information on the target structure, as the number of fringes in the PADs depends strongly on the symmetry of the electronic bound state.

Coulomb-corrected quantum interference in above-threshold ionization: Working towards multitrajectory electron holography

“…The same spider-like pattern is seen in [55,57], in which the quantum-trajectory Monte Carlo (QTMC) model is applied to mid-IR fields, and experimentally in [32,56], and it is attributed to these forward scattered trajectories. The on-axis contribution of orbit 3 to the overall PADs improves the agreement with the time-dependent Schrödinger equation (TDSE) [26,32,36] and with experiments [13,14,35,56], and can be seen in Coulomb-corrected computations in which orbit 3 has been included implicitly [52,55]. It is also worth noting that classical soft forward-scattered trajectories associated with the low-energy structure (LES) [6] are the same type of trajectories as orbit 3.…”

“…In previous studies [26,36] this orbit has been neglected, possibly because the corresponding prefactor strongly reduces the overall signal. Our studies show that, outside the p f z axis, this counteracts the fact that ionization probability along this orbit is quite high.…”

“…We provide direct evidence of how these patterns form, and show that they may be viewed as holographic type structures arising from different types of interfering trajectories. We follow the notation in [26,27,36,37], which classifies the trajectories that reach the detector directly as type 1 orbits, and those that leave from the opposite side and are deflected by the core without undergoing hard collisions as type 2 and 3 orbits. Previously overlooked holographic patterns that have been studied in this work include finer structures that arise from the intra-cycle interference of events separated by more than half a cycle, nearly horizontal, broad interference fringes stemming from the interference of type 2 and 3 trajectories, and a converging structure caused by the interference of type 1 and 3 trajectories.…”

“…In a previous publication [26], we have performed a direct analysis of how this pattern forms using the Coulomb Quantum Orbit Strong-Field Approximation (CQSFA) [27]. We have shown that the fan-shaped structure may be viewed as a holographic feature caused by the interference of the trajectories that reach the detector directly, with those that are deflected by the binding potential, but do not undergo hard collisions.…”

The plateau in above-threshold ionization: the keystone of rescattering physics

“…Reprinted figure with permission from [28], copyright (2008) by the American Physical Society. different attempts have been made to include the Coulomb field into the phases of the quantum orbits or, starting from a completely classical description, to augment the classical orbits by suitable phases [66,67,[107][108][109][110][111][112][113][114][115][116]. The exact relation of these approaches to the ISFA is not known.…”