Effect of the Coulomb potential on phase-of- phase attoclock spectroscopy: the hydrogen atom as an example

The phase-of-phase (POP) attoclock is a recently proposed approach to investigate the electron dynamics during a strong-field ionization process. This innovative approach has been utilized to accurately resolve the ionization time of photoelectrons with any momentum and extract the electron dynamics under the barrier. However, the impact of the Coulomb potential on the POP attoclock spectroscopy of neutral atoms remains an important issue largely unexplored. Here, we scrutinize the influence of the Coulomb potential on the contrast and POP spectra, taking the hydrogen atom as an example. By computing the POP spectroscopy using the three-dimensional time-dependent Schrödinger equation (3D-TDSE) with long-range and short-range potentials, we demonstrate that the Coulomb potential affects the contrast and POP spectra. Moreover, the differences for the POP spectra dramatically weaken as the electron energy increases, especially when the electron ejects along the principal axis of the laser polarization plane. Based on the strong-field approximation and Coulomb–Volkov approximation models, it is found that the dependence of the POP spectroscopy on the Coulomb effect is qualitatively consistent with the TDSE calculations. This work underscores the profound influence of the Coulomb potential on the measurement accuracy of the POP attoclock and holds great significance for advancing the POP attoclock spectroscopy.