Fano line shape metamorphosis in resonant two-photon ionization

Two-photon atomic ionization driven by time-locked XUV and IR pulses allows to study dynamics of Fano resonances in time and energy domains. Different time evolution of the two interfering pathways leading to a Fano resonance can be exploited to turn the Fano profile of the two-photon XUV/IR ionization into a symmetric Gaussian once the directly ejected photoelectron leaves the parent ion and cannot any longer absorb an IR photon. This line shape transformation allows for the direct determination of the resonant lifetime from the spectroscopic measurements without need for an extremely fine energy resolution. Ubiquitous nature of Fano resonances makes this determination a universal tool in diverse quantum systems ranging from nuclei to nano-fabricated solids.