Quantum control of femtosecond resonance-enhanced multiphoton-ionization photoelectron spectroscopy

We establish a theoretical model based on perturbation theory to show that the resonance-enhanced multiphoton-ionization photoelectron spectroscopy (REMPI-PS) in cesium (Cs) atom can be effectively enhanced and narrowed by appropriately shaping the femtosecond laser pulse, and the corresponding physical control processes can be well illustrated by considering the inter- and intragroup interferences involving on- and near-resonant three-photon excitation pathways. Consequently, a high-resolution REMPI-PS and fine energy-level diagram of the excited states can be obtained in spite of the broad femtosecond laser spectrum.