EN
Our group has recently carried out measurements of dispersed fluorescence from photo-excited N_{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_{2}^{+} and CO^{+} vary with the excitation energy. We associate this phenomenon with the existence of doubly excited states in N_{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.