Probing and controlling autoionization dynamics of atoms with attosecond light pulses

The time evolution of an autoionizing atomic system is studied theoretically in the presence of a moderately intense dressing laser pulse. We first examine how an autoionizing wave packet evolves in time in the absence of an external field, and take the single 2pns(1P) resonances in beryllium as examples. Alternatively, we study the electron dynamics where an attosecond extreme ultraviolet (XUV) pulse excites two autoionizing states in the presence of a strong time-delayed coupling infrared (IR) laser pulse. The IR can be viewed as a probe to extract or a control to modify the autoionization dynamics. The photoelectron and photoabsorption spectra are calculated for various time delays between the XUV and the IR pulses, and the results are compared with the available experiments. Finally, simulation of the coupled 2s2p(1P) and 2s2(1S) resonances in helium shows substantial spectral modifications by the dressing field parameters. Its analogy to electromagnetically induced transparency in the time domain is discussed.