1,721,172 research outputs found
Coplanar symmetric (e,2e) cross sections for krypton 4s ionization
No full textCopyright © Institute of Physics and IOP Publishing Limited 2003The triple-differential cross section for electron impact ionization of the 4s orbital of krypton (binding energy 27.5 eV) has been measured in coplanar symmetric kinematics. The experimental results are presented for outgoing electron energies of 85, 50, 20, 10 and 4 eV. The results are compared with two distorted wave Born approximation calculations; the influence of post-collision interaction (PCI) on the cross sections is investigated by incorporating correct final state boundary conditions in one of the calculations. The influence of PCI is found to be very important at the lower energies. Inclusion of the three-body final state boundary conditions improves the agreement between theory and experiment, but there are still significant discrepancies, indicating that additional physical effects (such as higher-order interactions) are important at lower energies.Matthew A Haynes, Birgit Lohmann, A Prideaux and D H Madiso
Coplanar symmetric (e, 2e) cross sections for argon 3s ionization
No full textCopyright © Institute of Physics and IOP Publishing Limited 2001The triple differential cross section for electron impact ionization of the 3s orbital in argon (binding energy 29.3 eV) has been measured in the coplanar symmetric geometry. The measurements have been performed at incident energies of 129.3, 69.3, 49.3 and 37.3 eV. This corresponds to detecting two equal outgoing electrons with energies of 50, 20, 10 and 4 eV. Comparisons with previous measurements for ionization of the 3p orbital of argon under the same kinematic conditions show significant orbital-dependent effects.Matthew A Haynes and Birgit Lohman
Dynamics in electron-impact ionization of H(2)O
Get PDFWe present multiply differential cross sections for electron-impact ionization of the water molecule. The experimental results are compared with theoretical cross sections calculated using a recently developed distorted-wave Born approach for molecules. The experimental cross sections exhibit a very large recoil scattering, which is not predicted by the theory. This has implications for applications of this theoretical approach in areas such as modeling of ionization in biological systems.D. S. Milne-Brownlie, S. J. Cavanagh, Birgit Lohmann, C. Champion, P. A. Hervieux, and J. Hansse
Recent theoretical progress in treating electron impact ionization of molecules
Get PDF(e,2e) ionization differential cross sections are presented for several molecules. We will compare experimental results with theoretical calculations using the molecular three body distorted wave (M3DW) approximations for H2, N2, H2O and Formic Acid (FA) using better wave-function for the molecules than we had in previous works. Generally, good agreement is found between the M3DW approach and experiments.Ola Al-Hagan, Chuangang Ning, Kate Nixon, Andrew Murray, Christopher Colyer, Mark Stevenson, Birgit Lohmann and Don Madiso
Gender and European Integration
Get PDFThe paper assesses the contribution of gender approaches to understanding Europeanintegration. It offers a conceptualization of such approaches as including a distinctontology, epistemology and methodology. While feminist literature on the EuropeanUnion is diverse, all such literature sheds light on the gendered process of Europeanintegration. The authors identify two distinct contributions of this literature: (a) itillustrates the relevance of movement actors and other advocates in shaping EU policies;(b) it shows that economic integration entails the creation of new gender regimes. Thepaper illustrates these contentions presenting case studies of the EU’s response to sextrafficking, the reform of the common agricultural policy, and of enlargement.
Elastic scattering of intermediate-energy electrons from C-60 molecules
Get PDFExperimental and calculated differential cross sections for elastic scattering of electrons by C60 molecules at collision energies of 100 to 500 eV are reported. The elastic differential cross sections were measured in a standard crossed-beam apparatus, while the calculations were performed employing the Schwinger multichannel technique at the static-exchange level. Diffraction effects, some due to the overall spherical-cage structure and some to scattering by individual C atoms, are observed in both the measured and calculated cross sections.L. R. Hargreaves, B. Lohmann, C. Winstead, and V. McKo
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Low-energy cathodoluminescence experiment with polarized electrons and a negative-electron-affinity GaAs target
Get PDFGöckel D, Baum G, Fromme B, Lehmann V, Lohmann B, Raith W. Low-energy cathodoluminescence experiment with polarized electrons and a negative-electron-affinity GaAs target. Physical Review B. 1990;42(11):7242-7244.We report new measurements of circularly polarized recombination radiation from highly doped p-type GaAs emitted under impact of longitudinally polarized electrons with an initial kinetic energy varied between 2 and 10 eV. The work function of the target crystal is lowered by cesiation and oxidation of the surface. The results are discussed and compared with our earlier measurements on a clean GaAs crystal surface and with photoluminescence data
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