Coexistence of interfering and noninterfering channels in resonant photoemission spectra across the Cu 2p -> 3d threshold

The interplay between the resonant Raman and the Auger-like regime across the Cu 2p-->3d absorption threshold was investigated. The resonant photoemission experiment performed on CuGeO3 unambiguously shows that a fraction of primary electrons is contributing to the interfering resonant Raman emission even when the noninterfering Cu L3M4,5M4,5 Auger emission is clearly detectable. At the 2p-->3d resonance the autoionization channel prevails over the direct photoemission channel and, in agreement with the Fano theory, a high q value (9+/-2) was extracted from the data by properly tracking the weak resonant emission above the absorption threshold.