The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform

Ronald E. Olson - One of the best experts on this subject based on the ideXlab platform.

  • AutoIonizatIon of He Atoms by Partially Stripped Ion Impact
    Physical Review A, 2005
    Co-Authors: S. Otranto, Ronald E. Olson
    Abstract:

    A study of the autoIonizatIon process induced by partially stripped Ion Impact is performed. Electron spectra in momentum space are predicted within a classical model for partially stripped Ions. The results are compared with those obtained for pure Coulomb-like projectiles. A quantum-mechanical extensIon of the Barrachina-Macek model is proposed for partially stripped projectiles. Structure on the electron angular distributIon arising in quantum and classical treatments is identified and compared. The presence of rainbow scattering interference is observed in the binary ring profile of the outgoing autoIonized electrons for positive-Ion Impact.

S. Otranto - One of the best experts on this subject based on the ideXlab platform.

  • AutoIonizatIon of He atoms induced by partially stripped Ion Impact
    Brazilian Journal of Physics, 2010
    Co-Authors: C.f. Martínez, S. Otranto
    Abstract:

    A study of the autoIonizatIon process induced by partially stripped Ion Impact is performed. The Barrachina-Macek model is extended to the case in which the projectile-emitted electron interactIon is represented by means of a non-Coulombic central potential at all times. Electron spectra in momentum space are predicted and compared to the Barrachina-Macek model and a recent model in which an asymptotically correct wave functIon was employed to treat this problem. The presence of rainbow scattering interference in the binary ring profile of the outgoing autoIonized electrons for positive Ion Impact is discussed based on the different models.

  • AutoIonizatIon of He Atoms by Partially Stripped Ion Impact
    Physical Review A, 2005
    Co-Authors: S. Otranto, Ronald E. Olson
    Abstract:

    A study of the autoIonizatIon process induced by partially stripped Ion Impact is performed. Electron spectra in momentum space are predicted within a classical model for partially stripped Ions. The results are compared with those obtained for pure Coulomb-like projectiles. A quantum-mechanical extensIon of the Barrachina-Macek model is proposed for partially stripped projectiles. Structure on the electron angular distributIon arising in quantum and classical treatments is identified and compared. The presence of rainbow scattering interference is observed in the binary ring profile of the outgoing autoIonized electrons for positive-Ion Impact.

Pablo D. Fainstein - One of the best experts on this subject based on the ideXlab platform.

  • Multicenter character in single-electron emissIon from H{sub 2} molecules by Ion Impact
    Physical Review A, 2004
    Co-Authors: Mariel E. Galassi, Roberto D. Rivarola, Pablo D. Fainstein
    Abstract:

    Single IonizatIon cross sectIons for heavy-Ion Impact on H{sub 2} are calculated by applying the continuum-distorted-wave-eikonal-initial-state model. We have used a representatIon of the bound-state initial wave functIon which takes into account the molecular character of the target. To describe the final continuum state we have used the two-effective-center approximatIon, previously employed with success to study electron capture from H{sub 2} by Ion Impact. Interference effects are also analyzed and the dependence of the oscillatIon frequency with the projectile velocity and ejectIon angle is presented. The importance of adequately describing the target as a molecule is emphasized.

  • CDW-EIS theory of IonizatIon by Ion Impact with Hartree-Fock descriptIon of the target
    Journal of Physics B: Atomic Molecular and Optical Physics, 1995
    Co-Authors: László Gulyás, Pablo D. Fainstein, A Salin
    Abstract:

    We have carried out a generalizatIon of the continuum-distorted-wave-eikonal-initial-state (CDW-EIS) approximatIon for Ion-Impact single IonizatIon where the interactIon of the active electron with the target is represented by a Hartree-Fock potential. We apply this model to the IonizatIon of He, Ne and Ar by proton and multiply-charged bare-Ion Impact. Doubly differential and total cross sectIons are calculated from each subshell. These cross sectIons summed over all subshells show a much better agreement with experimental data than those obtained from the previous formulatIons of the CDW-EIS approximatIon which use hydrogenic wavefunctIons with effective charges.

  • Two-centre effects in IonizatIon by Ion Impact
    Journal of Physics B: Atomic Molecular and Optical Physics, 1991
    Co-Authors: Pablo D. Fainstein, V H Ponce, Roberto D. Rivarola
    Abstract:

    When an atom is Ionized by Ion Impact, the electron is ejected into a final continuum state of a two-centre potential due to the Coulomb fields of the projectile and Ionized atom. The related effects on the electron yield or energy and angular distributIons are referred to as two-centre electron emissIon (TCEE). The present report is devoted to a discussIon of experimental and theoretical evidence of this TCEE. The use of heavy Ions or antiprotons as projectiles allows to unravel these effects by monitoring the two centre potential. On the theoretical side, the continuum distorted wave-eikonal initial state theory (CDW-EIS) accounts for the TCEE thus allowing a detailed interpretatIon of the experimental findings.

S. Radelaar - One of the best experts on this subject based on the ideXlab platform.

  • Measurement of Ion Impact energy and Ion flux at the rf electrode of a parallel plate reactive Ion etcher
    Journal of Applied Physics, 1991
    Co-Authors: A. Manenschijn, G. C. A. M. Janssen, E. Van Der Drift, S. Radelaar
    Abstract:

    An experimental study on the Ion Impact energy distributIon and the total Ion flux at the driven electrode of a parallel plate reactive Ion etcher is presented. Results are shown for 13.56 MHz discharges in Ar, Ar/H2, N2, O2, Cl2, and SF6/He over a pressure range of 0.3–40 Pa. The Ion Impact energy distributIon consists of a collisIon‐free part and a collisIon‐induced part. It is observed that in Ar, N2, O2, and Cl2 the collisIon‐induced part contains single and double peaks at regular energy intervals. This peaked structure is attributed to charge exchange processes in the sheath. Both the collisIon‐free part and the collisIon‐induced part of the Ion Impact energy distributIon are well described by a model based on a constant sheath width, a sinusoidal sheath voltage, and a power law for the electric field in the sheath. The only adjustable parameter in the model is the sheath thickness. The sheath thickness has also been determined independently from the total Ion current density using the Child–Langmuir law. The obtained values are in good quantitative agreement with each other and with the observed optical sheath thickness, demonstrating the overall consistency of the present approach.

Roberto D. Rivarola - One of the best experts on this subject based on the ideXlab platform.

  • Multicenter character in single-electron emissIon from H{sub 2} molecules by Ion Impact
    Physical Review A, 2004
    Co-Authors: Mariel E. Galassi, Roberto D. Rivarola, Pablo D. Fainstein
    Abstract:

    Single IonizatIon cross sectIons for heavy-Ion Impact on H{sub 2} are calculated by applying the continuum-distorted-wave-eikonal-initial-state model. We have used a representatIon of the bound-state initial wave functIon which takes into account the molecular character of the target. To describe the final continuum state we have used the two-effective-center approximatIon, previously employed with success to study electron capture from H{sub 2} by Ion Impact. Interference effects are also analyzed and the dependence of the oscillatIon frequency with the projectile velocity and ejectIon angle is presented. The importance of adequately describing the target as a molecule is emphasized.

  • Helium excitatIon by protons and highly-charged-Ion Impact
    Physical Review A, 1997
    Co-Authors: V D Rodríguez, C. A. Ramírez, Roberto D. Rivarola, J. E. Miraglia
    Abstract:

    The symmetric eikonal distorted wave method is extended to account for two-electron atom excitatIon by Ion Impact. In this formulatIon (SE2), the interactIon between the projectile and each one of the two target electrons is taken into account in the initial and final wave functIons by using the eikonal approximatIon. The active electron notIon is not employed as both electrons are treated the same. When single configuratIon target wave functIons are used, the SE2 transitIon matrix element can be expressed as a convolutIon of one-electron transitIon matrix elements. The theory is applied to the study of helium excitatIon by proton and highly-charged-Ion Impact. Experimental total and differential cross sectIon data are well reproduced. {copyright} {ital 1997} {ital The American Physical Society}

  • Two-centre effects in IonizatIon by Ion Impact
    Journal of Physics B: Atomic Molecular and Optical Physics, 1991
    Co-Authors: Pablo D. Fainstein, V H Ponce, Roberto D. Rivarola
    Abstract:

    When an atom is Ionized by Ion Impact, the electron is ejected into a final continuum state of a two-centre potential due to the Coulomb fields of the projectile and Ionized atom. The related effects on the electron yield or energy and angular distributIons are referred to as two-centre electron emissIon (TCEE). The present report is devoted to a discussIon of experimental and theoretical evidence of this TCEE. The use of heavy Ions or antiprotons as projectiles allows to unravel these effects by monitoring the two centre potential. On the theoretical side, the continuum distorted wave-eikonal initial state theory (CDW-EIS) accounts for the TCEE thus allowing a detailed interpretatIon of the experimental findings.