Multiphoton ionization with three-dimensional light fields

TL;DR

This paper demonstrates the generation and control of free-electron angular momentum wave packets via multiphoton ionization using 3D polarization-tailored ultrashort laser fields, enabling advanced imaging and spectroscopy of electronic dynamics.

Contribution

It introduces a novel method to produce and manipulate 3D light fields for controlling electron wave packets, surpassing previous planar polarization limitations.

Findings

First observation of free-electron angular momentum wave packets in 3D fields

Full 3D coherent control of electronic superposition states achieved

Imaging of spin-orbit dynamics in potassium $3d$ doublet using 3D pump-probe fields

Abstract

We report the first observation of free-electron angular momentum wave packets generated by atomic multiphoton ionization with bichromatic three-dimensional (3D) polarization-tailored ultrashort laser fields. These fields, created by the non-collinear superposition of two polarization-shaped pulses of different colors from a supercontinuum polarization pulse shaper, provide electric-field components along all spatial directions. The resulting photoelectron momentum distributions, recorded via velocity map imaging, demonstrate full 3D coherent control of electronic superposition states extending beyond the constraints of planar polarization fields by unlocking all dipole selection rules $\Delta m = 0,\pm1$. As an application, 3D pump-probe fields are used to image previously unobserved photoelectron wave packets mapping spin-orbit dynamics of the potassium $3d$ fine structure doublet. Our shaper-based approach establishes a route to fully controllable 3D light fields for chiral-sensitive light-matter interactions and ultrafast spectroscopy.