An electron that multiphoton ionizes in a gas is immediately subject to the light’s electric field that will control its short-term future. As a result of this control, we can use a gas of atoms or molecules to produce intense VUV or soft X-ray beams by forcing the electron to recollide and recombine with its parent ion. Since we can precisely control the infrared beam that creates the radiation, we can also synthesize attosecond soft X-ray pulses – pulses that are the shortest controlled events ever systematically produced (50-attoseconds). Such pulses, when applied to materials, allow us to measure electron dynamics within atoms, molecules or solids – the fastest measurements ever made.
But the attosecond pulse is not the whole story. The underlying attosecond electron is a well-timed, well-directed, collision physics-like probe. When applied to complex systems, the recollision electron will interact with the atom’s other electrons. I will describe how we can precisely measure the time delay associated with this interaction (1) and I will show that this time delay is only sensitive to multielectron dynamics (2,3). The recollision electron is the tool that is needed to measure the “ultimate time response of electronic matter”.
(1) Dong Hyuk Ko, Graham G. Brown, Chunmei Zhang and P. B. Corkum, “Near-field imaging of dipole emission modulated by an optical grating”
(2) Graham G. Brown, Dong Hyuk Ko, Chunmei Zhang and P. B. Corkum, “Characterizing Fano resonances during recollision”
(3) Graham G. Brown, Dong Hyuk Ko, Chunmei Zhang and P. B. Corkum, “Characterizing multi-electron dynamics during recollision”