Interference effects in the Auger decay of the resonantly excited 2p(3/2)(-1)3d state of argon

High resolution resonant Auger spectra have been measured at the VUV beam line at ELETTRA, Sincrotrone Trieste, while tuning the photon energy across the 2p(3/2)(-1)3d resonance of argon. A large variation of the branching ratio for decay into the spectator 3p(-2)3d and shakeup 3p(-2)4d channels is observed. The effect has not been seen previously in resonant inner-shell excitation and is attributed to the interference between the direct photoionization process and resonant Auger decay leading to the same final state.