Lifetime effects on the dissociation of core-excited N2 and CO molecules

Vibrational-resolved ion and ion-pair yield spectra of N-2 and CO taken at their 1s --> pi* resonance excitations reveal decay-channel-dependent core hole lifetimes. The linewidths of the yield spectra tend to be shortened when the number of electrons ejected in the deexcitation process increases, finally becoming narrower than the total ion yield or absorption natural lifetime width of the core-excited states of N-2 and CO, respectively. In contrast to this, the linewidths of the yield spectra for the singly charged molecular ions, N-2(+) and CO+, are shown to be broader than their corresponding natural linewidths. This linewidth shortening and broadening observed in the ion yield spectra are explained by the effect of different internuclear distances on the lifetime of an excited molecular state.