Direct Visualization of the Transverse Photoemission Position Within Molecules Via Strong-Field Photoelectron Holography

Laser-induced tunneling ionization triggers a broad class of strong-field phenomena in the attosecond community. The understanding and application of these ultrafast phenomena require accurate knowledge of the position information for the tunneling electron wave packet (EWP). Here, with strong-field photoelectron holography, we theoretically demonstrate a scheme to retrieve the position of the EWP emitted from molecules in the direction perpendicular to the tunnel. In our scheme, the photoelectron momentum distributions from strong-field tunneling ionization are obtained by solving the time-dependent Schrodinger equation. When the molecule is aligned with a nonzero angle to the linearly polarized laser field, a distinct shift of the holographic pattern in the photoelectron momentum distribution is observed. With the quantum-orbit model, we demonstrate that the shift of the holographic pattern is caused by a nonzero initial transverse position of the EWP immediately after tunneling. By tracing their exact correspondence and examining the shift of the holographic pattern, the transverse emission position of the tunnel-ionized EWP is probed accurately. Furthermore, we demonstrate that the complex Coulomb interaction can be safely canceled in our scheme by performing the scheme for both of the model molecules with the short-range and Coulomb potentials. The validity and accuracy of our scheme are confirmed by its application to different molecules, alignments, and laser parameters.