Impact of narrow-band excitation on resonant decay spectra

The influence of narrow-band excitation on the decay spectra of dissociative core-excited molecular states is investigated in detail. Surprising interference phenomena have been reported previously in the resonant Auger spectrum of HF of Pahl et al. [Phys. Rev. Lett. 80, 1865 (1998)]. Apart from a general quenching of the “atomic” contribution by detuning, pronounced interference patterns are found for small detuning above the resonance of the core-excited state. Utilizing the time resolution gained within the theory of wave-packet dynamics, the underlying interference mechanisms are analyzed thoroughly. Special attention is paid to the selection process of intermediate-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 transitions take place. In particular, information about the origin of the atomic transitions is obtained.