Fig. 4: Schematic diagram of the electron tunnelling via neigboring atom.

a The concept of the angular streaking protocol driven by a clockwise rotating elliptically polarized near-IR femtosecond laser pulse. The yellow surfaces show the laser-field dressed Coulomb potential well of Ar⁺-Kr⁺ after the electron removal from Ar, where the gradually varied blue area between two nuclei indicates the tunnelling exit. The other insets show the final momentum vector correlation between molecular orientation, electron momentum and the instantaneous laser vector. b The tunnelling site resolved final photoelectron momentum distribution in the polarization plane, where the red contour curves with pz_e > 0 corresponds to the electrons freed by laser field pointing from Kr⁺ to Ar, and vice versa