Resolving electron partial waves in multiphoton ionization of molecules

Resolving partial waves, including their amplitudes and phases, is crucial for understanding the intricate structure and dynamics of the photoelectron released. However, the knowledge is limited because of the complexities of the multiphoton interactions with molecules in the nonperturbative regime. Here, we address these challenges using an orthogonal two-color (OTC) scheme, which combines different photon energies and polarizations of the laser fields to produce characteristic photoelectron angular distributions (PADs) that vary with the laser phase. By analyzing the phase-dependent PADs, the partial waves, including their individual amplitudes and phases, involved in the nondissociative and dissociative single ionization of H₂ are unambiguously resolved. In addition, the interaction phases accumulated during the absorption of multiple photons of different polarizations are revealed. The OTC scheme works as a powerful tool to achieve a partial-wave decomposition of the photoelectron wave packet launched via multiphoton ionization and explore attosecond electron dynamics in strong laser fields.