Coherence of L2,3 − M22,3 Auger decay paths by energy selected photoionization of argon

L2,3 − M22,3 Auger decay in argon is an extremely well studied subject from the experimental, as well as the theoretical side. We add an additional insight by observing the process at photon excitation energy that introduces quantum coherence among different pairs of reaction paths or induces an essential exchange uncertainty along the same path. Coincidence measurements of ejected electron pairs are performed with ten independent electron analysers in plane perpendicular to the incoming photon beam.