Tracing nuclear wave-packet dynamics in diatomic molecules with XUV pump- and probe- pulses*

We traced the femtosecond nuclear wave-packet dynamics in ionic states of oxygen and nitrogen diatomic molecules employing 38 eV XUV pump and probe at the \underline {F}ree Electron \underline {Las}er in \underline {H}amburg (FLASH).\footnote{Y. H. Jiang \textit{et al.}, PRA \textbf{82}, 041403(R) (2010).} The nuclear dynamics is monitored via the detection of coincident ionic fragments using a reaction microscope and a split-mirror setup to generate the pump and probe pulses. By comparing measured kinetic-energy-release (KER) spectra with classical and quantum-mechanical simulations,\footnote{I. A. Bocharova \textit{et al.}, PRA \textbf{83}, 013417 (2011)} we identified electronic states of the molecular ions that are populated by ionization of the neutral molecule. The comparison of measured KER spectra for specific fragment-charge states allows assessing the relevance of specific dissociation paths.