Molecular dissociative ionization and wave packet dynamics studies using two-colour XUV+IR pump-probe spectroscopy

We present a combined theoretical and experimental study of ultrafast wave-packet dynamics in the dissociative ionization of H2 molecules as a result of irradiation with an extreme-ultraviolet (XUV) pulse followed by an infrared (IR) pulse. In experiments where the duration of both the XUVand IR pulses are shorter than the vibrational period of H2+, dephasing and rephasing of the vibrational wave packet that is formed in H2+ upon ionization of the neutral molecule by the XUV pulse is observed. In experiments where the duration of the IR pulse exceeds the vibrational period of H2+ (15 fs), a pronounced dependence of the Hþ kinetic energy distribution on XUV-IR delay is observed that can be explained in terms of the adiabatic propagation of the H2+ wave packet on field-dressed potential energy curves.