Femtosecond and Attosecond Spectroscopy in the XUV Regime

Attosecond-duration, fully coherent, extreme-ultraviolet (XUV) photon bursts obtained through laser high-harmonic generation have opened up new possibilities in the study of atomic and molecular dynamics. We discuss experiments elucidating some of the interesting energy redistribution mechanisms that follow the interaction of a high-energy photon with a molecule. The crucial role of synchronized, strong-field, near-IR laser pulses in XUV pump-probe spectroscopy is highlighted. We demonstrate that near-IR pulses can in fact be used to modify the atomic structure and control the electronic dynamics on attosecond timescales. Our measurements show that the Gouy phase slip in the interaction region plays a significant role in these attosecond experiments. We perform precision measurement of interferences between strong field-induced Floquet channels to extract the intensity and phase dependence of photoionization dynamics. Applications of emerging table-top ultrafast XUV sources in the study of core electron dynamics are also discussed.