Rescattering of Ultralow-Energy Electrons for Single Ionization of Ne in the Tunneling Regime

Abstract

Electron emission for single ionization of Ne by 25 fs, 1.0 PW/cm 2 laser pulses at 800 nm has been investigated in a kinematically complete experiment using a "reaction-microscope". Mapping the complete final state momentum space with high resolution a distinct minimum along the longitudinal momentum direction P e|| is observed at P e|| = 0 with respect to the laser polarization direction. Whereas tunneling theory predicts a maximum at the singularity our findings are in good agreement with recent semiclassical predictions which were interpreted to be due to "recollision".

Scaling of the Low-Energy Structure in Above-Threshold Ionization in the Tunneling Regime: Theory and Experiment

“…One finding deviating from the SFA prediction is the observed low-energy momentum distribution [12,13] of the recoiling ions. Several explanations have been proposed and are still under debate, tracing the effect to the long-range Coulomb potential [14][15][16], Freeman resonances [17,18], or the persistence of ATI peaks in the tunneling regime [19,20].…”

Momentum distributions of sequential ionization generated by an intense laser pulse

“…Due to the capabilities of modern experiments (especially since the advent of cold-target recoil-ion-momentum spectroscopy), both the total yield and the ion-momentum distributions can be measured [12][13][14][15][16][17][18]. It was found that, at high laser intensities, momentum distributions of multiply charged ions along the polarization direction have a Gaussiantype shape with the maximum at zero momentum [14,15,19].…”

Unexpected breakdown of the simple man's model for strong-field photoionization in the high-energy recollision region

“…The significance and simplicity within this simple man's model lie in that, after being pumped into the continuum state, the interaction of the electron with the core is much weaker than that with the laser field and, thus, safely can be neglected. However, recent experimental observations have provided strong evidence of the breakdown of the simple man's model, which is based on strong-field approximation (SFA) in both ATI [4][5][6] and HHG [7] processes. These investigations, focused on the low-energy regions of ATI and HHG spectra, have revealed a significant role of the Coulomb interaction of the electron with the ion, which, however, may not be a surprise because, for the slow electrons, their motions can easily be influenced by the Coulomb field [8].…”

“…Actually, the signature of the Coulomb influence in the high-energy recollision region can be retrieved from the low-energy structure (LES) recently observed in ATI [4,5,9]. The LES is formed due to the transverse momentum concentration of the ATI electrons as evidenced by the energyresolved angular distribution (AD) of the ATI electrons in Fig.…”