Table-Top Coherent Soft X-ray Sources and Their Applications to Attosecond Spectroscopy

High-order harmonic generation (HHG) driven by strong-field femtosecond laser pulses provides a reliable way of producing coherent extreme ultraviolet (EUV) and soft X-ray pulses on table top scale. The time duration of the high-order harmonic pulses can be as short as 50 attosecond (as = 10^(-18) s), which corresponds to the time scale of electronic motion in atoms, molecules, and nano-structures. Since the HHG process itself is highly dependent on the driving laser parameters and medium characteristics, it is an extremely useful tool for studying the structure of the HHG medium. Moreover, generated EUV/soft harmonic X-ray pulses have been the only proven tool of experimental attosecond science.

Researchers at MIT, USA, and UFPE, Brazil, will establish a multi-year collaboration plan to promote the research on compact table-top coherent EUV/soft X-ray sources and their applications to ultrafast spectroscopy of gas, molecules, and nano-structures. The research collaboration under MISTI/FACEPE seed fund is expected to initiate a long-term program with three main research goals: (1) optimization of the HHG process in molecules and nano-structures towards high-flux EUV/soft X-ray generation, (2) ultrafast imaging of atomic and molecular orbital structures, and 3) ultrafast pump-probe study of molecules and graphene using soft X-ray/EUV and UV pulses on the femtosecond and attosecond time scale.