Electron Wave Packet Interferences in Ionization with Few-Cycle Laser Pulses and the Dissociative Photoionization of D2 with Ultrashort Extreme Ultraviolet Pulses

Abstract

In this work, using a Reaction Microscope, three-dimensional (3D) electron (and ion) momentum spectra have been recorded for carrier-envelope-phase (CEP) stabilized few-cycle (<5 fs),intense (~4*10^14 W/cm^2) laser pulses (740 nm) impinging on He. Preferential emission of low energy electrons (Ee < 15 eV) to either hemisphere is observed as a function of the CEP. Clear interference patterns emerge in momentum-space at CEPs with maximum asymmetry, interpreted as attosecond interferences of rescattered and directly emitted electron wave packets by means of a simple model. These measurements provide an opportunity to potentially image the time-dependent potentials in atoms and molecules. In the second part of this work, a Reaction Microscope was designed, constructed and brought into operation to study the dissociative photoionization of D2 with ultrashort (~15 fs) XUV (~32 eV) pulses. The coupling of dissociation dynamics of D2^(+) to the ionized electron through the autoionization channels results in breaking of the symmetry of the dissociation process, in qualitative agreement with theory and earlier measurements and observed here for the first time with ultrashort pulses. With control over the duration of the XUV pulses in future experiments, temporal evolution of the autoionization in simple diatomic molecules can eventually be studied.