Since Keldysh's pioneering work fifty years ago, the theory of strong-fieldapproximation has achieved great success in providing a solid foundation tostrong-field atomic ionization. However, the neglect of Coulomb interactionremains a long-standing gap between the well-established optical-tunnelingpicture and the experimental observations, which has been highlighted in thepast decade by a series of striking disagreements extending from the low energyregime near the ionization threshold to the intermediate energy around twicethe ponderomotive energy, not only in longitudinal direction but alsotransverse direction. Here we report that the gap can be largely bridged withthe aid of an effect named as glory, which is associated with a specific typeof singularity concealed in Coulomb forward rescattering. We reveal that thetrajectory lying exactly on the singular point dominates both the photoelectronlongitudinal and transverse momentum distribution, which directly connectstunneling theory with photoelectron distribution after post-tunnelingpropagation.
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