Geometrical information on core-excited states obtained from interference quenching of vibrational states in resonant x-ray photoemission

The determination of the core-excited state geometry is an important issue in x-ray spectroscopy. Such information is valuable in different scientific applications. It is demonstrated that the cross section of the resonant photoemission for the one-phonon final state can be almost completely quenched for negative detuning. From the theoretical point of view this condition means that the real part of the scattering amplitude equals zero. A simplified model of this effect is presented in order extract the main physics and in order to give a simple relation between the detuning value Ω_cs, for which the one-phonon line is passing through a total minimum, and the molecular geometry.