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Time-domain atomic dynamics with attosecond XUV pulses

The interaction of quasi-free electrons with intense laser fields gives rise to phenomena such as high harmonic generation upon rescattering with the parent ions or steering of the electron trajectories. Both effects can be utilized for the realization of time-resolved electron spectroscopy on free atoms. Extreme ultraviolet (XUV) pulses with photon energies exceeding 90 eV are sufficiently energetic to excite inner atomic electron shells and durations down to 250 as permit a time-based view of the extremely rapid relaxation processes that follow the creation of an atomic core-hole. To this end, a strong laser field serves as an ultrafast local probe for an escaping secondary electron by sampling the formation of its wave packet in real time. The capability of the technique was demonstrated in a time-domain study of the MNN Auger decay in krypton.