Is there interference in the resonant Auger electron spectra of N 1s and O 1s → 2π core excited NO?

High-resolution, angle-resolved resonant Auger electron spectra of the NO molecule in the regions of both N and O 1s --> 2pi core electron excitations are presented. A large number of vibrational final states are resolved due to high energy resolution. Calculations based on lifetime vibrational interference (LVI) theory neglecting interference between different electronic intermediate states and between direct and resonant channels have been performed. A comparison between theoretical and experimental spectra shows that LVI theory describes the major spectroscopic features quite well. The same holds for the evolution of the angular averaged partial cross sections with the change of excitation energy. The angular distribution of particular vibrational final states are, however, not described successfully with LVI calculations at the present level of sophistication. A theoretical analysis supports that one reason for this deviation is electronic state interference. (C) 2002 Elsevier Science B.V. All rights reserved.