1,720,977 research outputs found
Spin polarization of photoelectrons from zinc atoms in the 3d(9)4s(2)4p autoionization region
No full textKuntze R, Bowering N, Salzmann M, Heinzmann U, Martin NLS. Spin polarization of photoelectrons from zinc atoms in the 3d(9)4s(2)4p autoionization region. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. 1996;29(5):1025-1033.We have measured the energy dependence of the dynamical spin-polarization parameters for photoelectrons from zinc atoms in the wavelength region from 100 nm to 115 nm. The pronounced structure near the Zn(3d(9)4s(2)4p)P-1(1),D-3(1),P-3(1) resonances found in previously measured absorption spectra also occurs in the spin-polarization parameters. From the experimental results the dipole transition matrix elements including the relative phase shift difference have been determined. The data are also compared with an existing R-matrix calculation and a new calculation employing semi-empirical Slater-Condon parameters
The role of molecular state and orientation in harpooning reactions: N2O on Cs/Pt(111)
No full textBrandt M, Greber T, Bowering N, Heinzmann U. The role of molecular state and orientation in harpooning reactions: N2O on Cs/Pt(111). PHYSICAL REVIEW LETTERS. 1998;81(11):2376-2379.The interaction of a beam of state selected and oriented N2O molecules with 1 ML of Cs on Pt(lll) is studied by means of exoelectron emission. While the immediate emission is absent for the impact of ground-state molecules it is present when the molecules are in the first excited n(2) = 1 vibrational bending mode. The observed orientational anisotropy agrees with a theory that includes the molecular orientation. The results can be explained in a picture where N2O approaches the surface with the O end and where-after harpooning-an exoelectron is emitted
Photoionization of an open-shell atom with open-shell final ionic state: A spin-resolved study of photoelectrons above the Tl+ (6s6p) P-3(1) limit
No full textKuntze R, Salzmann M, Bowering N, Heinzmann U, Cherepkov NA. Photoionization of an open-shell atom with open-shell final ionic state: A spin-resolved study of photoelectrons above the Tl+ (6s6p) P-3(1) limit. In: Journal of Electron Spectroscopy and Related Phenomena. JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA. Vol 79. ELSEVIER SCIENCE BV; 1996: 335-338.Spin-resolved measurements of the dynamic photoionization parameters for photoelectrons from thallium atoms are presented for the Tl+ (5d(10)6s6p) P-3(1) final ionic state in the complex spectral region from 90 to 77 nm. For a complete description of this ionization process more than three transition matrix elements are needed since neither the initial nor the final state has closed-shell configuration. An approximate determination of matrix elements and phase shift differences is carried out. In addition, it is discussed how complete information may in principle be obtained
SPECTRAL DIAGNOSIS OF A LASER-PRODUCED XUV SOURCE USING A DIGITAL CAMERA SYSTEM WITH PINHOLE TRANSMISSION GRATING
No full textBOWERING N, DOHRING T, GARNER U, Heinzmann U. SPECTRAL DIAGNOSIS OF A LASER-PRODUCED XUV SOURCE USING A DIGITAL CAMERA SYSTEM WITH PINHOLE TRANSMISSION GRATING. In: Laser and Particle Beams. LASER AND PARTICLE BEAMS. Vol 9. CAMBRIDGE UNIV PRESS; 1991: 593-601.For spectral diagnosis, a repetitive laser-produced soft-X-ray source was examined in the range 2-40 nm using a spectrometer containing a pinhole transmission grating, an image converter, and a CCD camera. Via digital recording the detection system provides fast on-line data accumulation with spectral and spatial resolution. With this detector the performance of the light source was studied with respect to spectral emission characteristics, long-term stability, and reproducibility by recording spectra for different solid targets and liquid lead
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Reaction of NO and CO on a Rh(100) surface studied with gas-phase oriented NO
No full textBrandt M, Muller H, Zagatta G, Bowering N, Heinzmann U. Reaction of NO and CO on a Rh(100) surface studied with gas-phase oriented NO. In: Surface Science. SURFACE SCIENCE. Vol 352. ELSEVIER SCIENCE BV; 1996: 290-294.The reaction of NO with CO adsorbates has been studied in a supersonic molecular beam experiment with gas-phase oriented NO molecules incident on a CO-precovered Rh(100) surface. Two quadrupole mass analyzers mounted behind the rhodium target record the yield of scattered and desorbed NO as well as the reaction product CO2 as a function of time. The CO2 signal strongly depends on the initial NO orientation, that is to say, preferential N-end or O-end collisions at normal incidence on the surface. The corresponding CO2 reaction asymmetry shows a very high value of 0.35 at the beginning of the CO2 production and cannot be explained solely by an orientation dependent trapping or sticking of the NO molecules on the CO precovered surface. This points to a transition in the reaction mechanism from a direct to an indirect surface reaction channel
Variations on the Author
Full text link“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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Photoelectron spin polarization in autoionization of NO molecules prepared by jet cooling
No full textSalzmann M, Muller M, Bowering N, Heinzmann U. Photoelectron spin polarization in autoionization of NO molecules prepared by jet cooling. JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. 1999;32(11):2517-2528.The photoionization of NO molecules is studied using angle- and spin-reserved photoelectron spectroscopy with circularly polarized synchrotron radiation. The spin-orbit splitting is resolved by preparing only the X (2)Pi(1/2) component of the ground state in a helium-seeded supersonic expansion. A pronounced spin polarization in the angular distribution is found for the cold beam when the strong autoionization resonance at 13.82 eV photon energy is excited. The polarization parameters A, xi and alpha are determined for the nu = 2 and 3 vibrational levels of the NO+ X (1)Sigma(+) final ionic state. The results lead to the conclusion that resonances with (2)Sigma(+) and (2)Delta symmetry contribute with similar intensity. The dominant contributions to the dipole transition matrix elements of the emitted electron waves can be derived approximately
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