Observation and resonant x-ray optical interpretation of multi-atom resonant photoemission effects in O1semission from NiO

Abstract

ABST RACTWe present experimental and theoretical results for the variation of the O 1s intensity from a NiO(001) surface as the excitation energy is varied through the Ni 2p 1/2,3/2 absorption resonances, and as the incidence angle of the radiation is varied from grazing to larger values. For grazing incidence, a strong multi-atom resonant photoemission (MARPE) effect is seen on the O 1s intensity as the Ni 2p resonances are crossed, but its magnitude decreases rapidly as the incidence angle is increased. Resonant x-ray optical (RXRO) calculations are found to predict these effects very well, although the experimental effects are found to decrease at higher incidence angles faster than those in theory. The potential influence of photoelectron diffraction effects on such measurements are also considered, including experimental data with azimuthal-angle variation and corresponding multiple-scatteringdiffraction calculations, but we conclude that they do not vary beyond what is expected on the basis of the change in photoelectron kinetic energy. Varying from linear polarization to circular polarization is found to enhance these effects in NiO considerably, although the reasons are not clear. We also discuss the relationship of these measurements to other related interatomic resonance experiments and theoretical developments, and make some suggestions for future studies in this area.2

X-ray absorption intensity at high-energy region

“…In contrast to the high-energy region, different many-body effects play some important roles in addition to one-electron effects such as XANES in near edge region. Radiation field screening can contribute to the branching ratio of L 2 /L 3 for transition metals which deviates from the simple statistical ratio [17], multi-atom resonant photoemission (MARPE) [18,19], and core-hole moving effects after the core excitation [20] .…”

Resonant Interatomic Auger Transition in Chalcopyrite CuInSe2

“…The photoionized Cu2p hole (binding energy 933 eV, labeled as c) is filled by an electron from the overlying Cu3p state (75 eV, A1) due to the Coulomb interaction, and the energy released in this process is spent on the ejection of an electron located on the neighboring indium atom In4d (17 eV, B2) into free state f. The detector measures the intensity of the outgoing electrons versus their kinetic energy or Auger spectrum of CuL3M2,3InN4,5. Usually the intensity of the interatomic transition is vanishingly small in comparison with the intra-atomic transition, say СuL3M2,3V (V denotes a valence state), since the distance determining the energy of the Coulomb interaction 2 1 2…”

“…The study of interatomic Auger transitions is of fundamental importance for understanding the evolution of excited states in matter. It was stated that the photoemission associated with a certain electronic level of the given atom “A” can be significantly changed in intensity as the photon energy passes through the absorption edge of the core level of the neighboring atom “B.” This effect was called a multiatomic resonant photoemission (MARPE). Its macroscopic analogue can be the so‐called resonant X‐ray optical dielectric model, which considers the change in the complex dielectric constant of the substance as it passes through the corresponding resonance .…”

“…The study of interatomic Auger transitions is of fundamental importance for understanding the evolution of excited states in matter. It was stated [1][2] that the photoemission associated with a certain electronic level of the given atom "A" can be significantly changed in intensity as the photon energy passes through the absorption edge of the core level of the neighboring atom "B". This effect was called a multiatomic resonant photoemission (MARPE).…”

Interatomic resonant Auger effects in core-level photoemission from NO and CS2molecules

“…In several recent studies of solids, it has been pointed out that photoelectron emission from a given core level in a multiatom system can be significantly influenced by scanning the photon energy through a resonant absorption edge of 3 Present address: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan. some neighbouring atom in the systems [1][2][3][4][5][6]. For example, it was originally observed in a crystal of MnO that O 1s photoemission intensities are enhanced for photon energies matching the resonance of Mn 2p → 3d [1][2][3].…”