Ultra-Short Lived Non-Rydberg Doubly Excited Resonances Observed in Molecular Photoionization of CO and N$\text{}_{2}$ Molecules

Our group has recently carried out measurements of dispersed fluorescence from photo-excited N$\text{}_{2}$ and CO molecules in 19-34 eV excitation energy range using the Swedish synchrotron radiation facility MAX in Lund. The experimental results show that relative intensities of the fluorescence from different vibrational levels of the excited N$\text{}_{2}^{+}$ and CO$\text{}^{+}$ vary with the excitation energy. We associate this phenomenon with the existence of doubly excited states in N$\text{}_{2}$ and CO in the corresponding energy regions. Our results show that the widths of the newly revealed states correspond to their lifetimes of the order of few femtoseconds.