Hideo Sambe

An Interpretation of the O2 Auger Electron Spectrum.

Abstract The Auger electron spectrum of O 2 is interpreted by comparing with other spectra, such as the photoelectron spectrum, the electron impact mass spectrum, and the double charge transfer spectrum. Each of these four spectra obeys its own selection rule; the difference in the selection rules plays a key role in our interpretation. Auger decays following a core shake-up excitation are identified in the O 2 spectrum for the first time. Many of the previous assignments are revised.

The σ− selection rule in electron attachment and autoionization of diatomic molecules

Abstract It is shown theoretically that Σ + ⇐ Σ − transitions in electron attachment and autionization of diatomic molecules are forbidden. For the verification of this selection rule, two experimental examples are given.

Identification of resonantly excited auger electron spectra for N2

Abstract The Auger electron spectra (AES) of N2 excited with 5 keV electrons, 401 eV photons, and 418 eV photons are compared. This comparison implies that features in the 350–355 eV region of the electron-excited AES arise from the resonantly excited IsN−1lπg state. For the first time, Auger transitions initiating from the lsN−1lπu−11πg 5p Rydberg state, excited resonantly with 418 eV photons, are identified in the AES.

Rydberg states converging to the N2+2 ionized states

Abstract The binding energy of a given Rydberg electron, nl , bound by a doubly ionized atomic core, is compared with the binding energy of the same Rydberg electron, nl , bound by a singly ionized atomic core. It is shown that the ratio between these two binding energies is nearly independent of the nature of the atomic cores. Assuming that this independence extends to diatomic molecules, we have estimated the binding energies of the Rydberg electrons bound by the N 2+ 2 ion. Using these binding energies and the equilibrium internuclear distances of N 2+ 2 , we have identified, for the first time, Rydberg states converging to the N 2+ 2 ionized states in the core-level and the valence-level photoelectron spectra. Good agreement between the estimated and the observed Rydberg-state energies indicates that the assumption used above is valid.

Dissociative electron attachment in NO

Previously reported experimental data on dissociative electron attachment (DEA) in NO are reinterpreted. The negative‐ion yield resulting from DEA in NO has peak intensities at electron energies around 8 and 9 eV. It is demonstrated that the 8 and 9 eV peaks are due to O− ions and long‐lived N− ions, respectively. It is also shown that the O− ions are produced via the single repulsive state, NO−(1π−12π2)1Δ. The possibility that two or more NO− repulsive states might be involved is ruled out. It is further argued that the long‐lived N− ions are produced via electron attachment to an excited state of NO, rather than to the ground state. The responsible excited state is believed to be the metastable NO(1π−12π)4Π state.

Dissociative electron attachment of O2: a solid-state effect on potential curve crossing

Abstract Previously published data on electron stimulated desorption (ESD) from condensed O 2 or O 2 in solid matrices are reanalyzed. In the gas phase, the O 2 − ( 2 Σ g + ) resonant state at 8.5 eV is known to dissociate predominantly into the second lowest limit. In this paper we point out that this dissociation requires a non-adiabatic curve crossing. In the condensed phase or in solid matrices, this resonant state is found to dissociate adiabatically into the lowest limit as well as non-adiabatically into the second limit. Furthermore, we find that the branching ratio strongly depends on the kinetic energy of the dissociating atoms. The singlet excited oxygen atom, O ∗ ( 1 D), formed upon dissociation into the second limit, is found to participate in an anion complex formation via in-cage recombination.

The 3σu* resonance of O2 chemisorbed on Pd(111) and Pt(111)

Abstract The ν = 0 → 1 vibrational excitation function for O 2 chemisorbed on a Pt(111) surface is reported for the incidence election energies 1–9 eV. This measurement, combined with experimental results for chemisorbed O 2 /Pd(111) previously reported in the literature, shows the presence of the 3σ u * resonance just above the vacuum level.

Comparison of autoionization and photoelectron spectra for CO

Abstract Photoelectron spectra and the autoionization portion of the Auger spectra are compared for CO. Eight final states of the photoelectron spectra coincide with those of the autoionization spectra: three of them are the well-known one-hole states and the other five are two-hole—one-electron states. A photoelectron band at 27.4 eV is identified for the first time by its exact match to the strongest band of the autoionization spectra. The symmetries of these and other two-hole—one-electron states are induced by comparing the intensifies of X-ray and UV photoelectron spectra.

An interpretation of the N2 photoelectron spectrum

Abstract The inner-valence (20–36 eV) photoelectron spectrum of N 2 is interpreted by comparing with various spectra (such as absorption, N + yield, fluorescence-yield, and core-level photoelectron spectra). This comparative study confirms the previous assignments on the bands at 25.3 and 29.0 eV and clarifies the controversial assignments on the bands at 32.6 and 35 eV (weak). Also, this study identifies for the first time a weak but sharp band at 33.3 eV.

AFM study of topographical changes on aluminum surfaces in sulfuric acid under low current anodic dissolution

Abstract A study of the anodic dissolution of polycrystalline aluminum utilizing in-situ atomic force microscopy (AFM) is reported. Terraced pyramidal walls with a constant characteristic width of 300–400 nm running relatively parallel to each other appear within a few minutes of dissolution. Upon further dissolution, these pyramidal walls are reduced to square terraced pyramids or ziggurats of constant width. AFM contour and profile plots reveal the extremely square and flat surfaces of the square plateaus on top of the ziggurats, all of them having the same size. Under the dissolution conditions utilized, nucleation occurs at dislocation sites with primarily layer-by-layer dissolution. A long-range interaction between approaching dissolution fronts decreases the dissolution rate leaving the terraced pyramidal walls. This interaction is interpreted to arise from band bending in the oxidic layer existing on the surface. These features suggest that a strong role in the dissolution kinetics is played by the non-local potentials caused by the electronic charge and band bending on the oxide layer. The terracing of the walls is believed to result from a short-range or chemical dissolution effect. Possible applications of these prepared surfaces are also discussed.