Impact of narrow-band excitation on resonant decay spectra

The influence of narrow-band excitation on the decay spectra of dissociativ e core-excited molecular states is investigated in detail. Surprising inter ference phenomena have been reported previously in the resonant Auger spect rum of HF of Pahl et al. [Phys. Rev. Lett. 80, 1865 (1998)]. Apart from a g eneral quenching of the "atomic'' contribution by detuning, pronounced inte rference patterns are found for small detuning above the resonance of the c ore-excited state. Utilizing the time resolution gained within the theory o f wave-packer dynamics, the underlying interference mechanisms are analyzed thoroughly. Special attention is paid to the selection process of intermed iate-state eigenfunctions accompanying narrow-band excitation. We present a method that enables the assignment of different contributions in the decay spectrum to the internuclear distances at which the corresponding transiti ons take place. In particular, information about the origin of the atomic t ransitions is obtained. [S1050-2947(99)00208-5].