High resolution photoelectron-Auger-electron coincidence study for the L_23m_23M_23 transitions in argon

We report a high-resolution coincident experiment between the Ar 2p1/2 and 2p3/2 photoelectrons and subsequently emitted L23-M23M23 Auger electrons, where the 2p photoelectrons were ionized far above the threshold. We demonstrate the applicability of the coincidence method when separating the different ionization and decay channels even in the case of strongly overlapping peaks. The measurement was carried out with a new high-energy-resolution electrostatic analyzer that is capable of recording the single and coincidence spectra at large range of emission angles simultaneously. An anomalous value was found for the 2P3/2-(3P012/1D2) intensity ratio in the 2p3/2 coincidence spectrum, while all the other relative intensities are in good agreement with the previously published data. The possible reasons for the difference are discussed.