Imaging of Attosecond Electron Wave Packets

A new experimental technique for the generation of XUV continua has been recently demonstrated that is based on the polarization gating method with few-cycle phase-stabilized driving pulses. Using aluminum filters of different thicknesses, the chirp of the attosecond pulses can be compensated. The carrier-envelope phase of the IR laser and the width of the polarization gate can be adjusted to vary the number of attosecond pulses that are created upon subsequent half-cycles of the IR driving field. We have utilized velocity-map imaging (VMI) in combination with this XUV source to record the dynamics of attosecond electron wave packets in the presence of a strong IR-field. Electron wave packets were created upon XUV-ionization of helium. Using an isolated attosecond pulse, the momentum shift of the electron wave packet in the IR-field can be observed with full angular resolution.