Investigating multiphoton resonances with Laser Induced Electron Diffraction

Photoionization of atoms or molecules in electromagnetic fields occurs via absorption of one or more photons. Once ionized, if the laser is linearly polarized, the photoelectron may revisit and recollide with the parent ion. This rescattering event can be elastic, inelastic or recombination. In recent years, the elastic channel has received considerable attention, as it facilitates the extraction of accurate electron-ion elastic differential cross sections from measured 3D photoelectron angular distributions, a technique called laser induced electron diffraction (LIED). Thus far, it was shown that LIED works very well in the strong field limit, when the return electron energy is exceeding 50-100 eV. Here, we report LIED measurements in the multiphoton regime in atoms and small molecules, performed at significantly lower electron return energies, and discuss the essential role of multiphoton resonances in LIED.