Tracing attosecond bound electronic dynamics by sub-cycle electron wavepacket interferometry

X. XIE; S. ROITHER; D. KARTASHOV; D. G. ARBÓ; E. PERSSON; S. GRÄFE; M. SCHÖFFLER; A. BALTUSKA; J. BURGDÖRFER; M. KITZLER

Aarhus

Conferencia; 11th European Conference on Atoms Molecules, and Photons - ECAMP X; 2013

Organizing Commitee

We experimentally and theoretically demonstrate a self-referenced wavefunction retrieval of a valence-electron wave packet created by moderately strong-field ionization with a cycle-sculpted two-color laser pulse. We isolate sub-cycle interferences in the three-dimensional electron momentum spectra measured for helium and neon as a function of the relative phase phi between the two colors. These sub-cycle interferograms encode the quantum phase difference of pairs of electron wavepackets that are timed to each other with attosecond precision. As a result, we are able to extract the sub-cycle phase-evolution of the laser-driven complex bound-state wavefunction during strong-field ionization. We find a strong deviation from the usually assumed linear rise which we attribute to a minute (<1%) but significant transient population of excited states. Thus, our experiment characterizes the formation of a bound electronic wavepacket as it occurs