1,720,963 research outputs found
PFI-ZEKE spectroscopy of the (2)Pi spin-orbit components of HBr+
No full textIrrgang R, Drescher M, Gierschner F, Spieweck M, Heinzmann U. PFI-ZEKE spectroscopy of the (2)Pi spin-orbit components of HBr+. In: Journal of Electron Spectroscopy and Related Phenomena. JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA. Vol 80. ELSEVIER SCIENCE BV; 1996: 5-8.The PFI-ZEKE method was applied for examination of the rotational structure of the (2) Pi spin-orbit components of HBr+ (v(+)=0). Precise absolute values for the position of rotational thresholds were obtained. Additional lines not compatible with ionization thresholds are attributed to slow electrons from autoionizing states attached to neutral molecules and field-ionized by the extraction pulse
High-resolution experimental determination of the angular distribution and spin polarization of xenon 7d ' and 9s ' photoelectrons and comparison with theoretical results
No full textSpieweck M, Drescher M, Gierschner F, Irrgang R, Heinzmann U. High-resolution experimental determination of the angular distribution and spin polarization of xenon 7d ' and 9s ' photoelectrons and comparison with theoretical results. PHYSICAL REVIEW A. 1998;58(2):1589-1591.Using narrowband tunable linearly br circularly polarized VUV radiation an examination of the dynamical parameters describing the autoionization process of atomic xenon was performed. With a resolving power of similar to 10(5) in the excitation step a fully resolved determination of the position, magnitude and shape of the angular distribution and integral spin-polarization resonances was possible for the low Rydberg orders n=7 and n=9 of the d and s series, respectively. Comparisons are drawn between the experimental data and some theoretical calculations published in recent years. [S1050-2947(98)00108-5]
A laser light source for circularly polarized VUV radiation
No full textIrrgang R, Drescher M, Gierschner F, Spieweck M, Heinzmann U. A laser light source for circularly polarized VUV radiation. MEASUREMENT SCIENCE & TECHNOLOGY. 1998;9(3):422-427.A laser-based light source for circularly polarized VUV radiation generated by nonlinear sum-frequency mixing is described. By choosing an appropriate nonlinear resonant process a light flux of up to 6 x 10(10) photons s(-1) at a bandwidth smaller than 1.2 cm(-1) is achieved. The determination of the polarization state is performed by means of using a four-mirror analyser. A degree of circular polarization greater than 0.99 was found for several mixing processes. These properties make this instrument an ideal source for high-resolution spectroscopic studies of polarization-dependent photo-ionization or photoemission at photon energies up to 14 eV
High resolution single-photon ionization of HBr in the spin-orbit autoionization region
No full textIrrgang R, Bowering N, Drescher M, Spieweck M, Heinzmann U. High resolution single-photon ionization of HBr in the spin-orbit autoionization region. JOURNAL OF CHEMICAL PHYSICS. 1996;104(22):8966-8972.The rotationally resolved photoelectron yield in the ionization of jet-cooled HBr was measured in the energy range between the spin-orbit split (2) Pi ionic thresholds. For single-photon excitation, narrow-band VUV radiation was generated by resonant frequency mixing. The spectrum is complex due to interaction of autoionizing resonances belonging to several series converging to different rotational states of the ion core. For low Rydberg orders, n less than or equal to 11, a description of angular momentum coupling according to Hund's case (c) is found to be appropriate. An assignment of higher Rydberg series in the range of 17 less than or equal to n less than or equal to 20 was made in Hund's case (e) coupling scheme by comparison with the corresponding photoionization spectra of Kr, HI, and HCl. (C) 1996 American Institute of Physics
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
Spin polarization of zero kinetic energy electrons from HBr
No full textDrescher M, Irrgang R, Spieweck M, Heinzmann U, Cherepkov NA, Lefebvre-Brion H. Spin polarization of zero kinetic energy electrons from HBr. JOURNAL OF CHEMICAL PHYSICS. 1999;111(24):10883-10886.The range of observables in zero kinetic energy (ZEKE) electron spectroscopy of molecules, previously restricted to the total electron intensity, was extended by measuring the integral spin polarization of ZEKE electrons at the HBr Omega(+)=3/2 thresholds after single-photon excitation with narrow-band circularly polarized light. A comparison with calculated values from multichannel quantum defect theory underlines the importance of autoionization for the decay dynamics. (C) 1999 American Institute of Physics. [S0021-9606(99)00548-6]
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
Experimentelle Realisierung von frequenzkonvertierter ns-VUV- und fs-EUV-Strahlung für Photoelektronenflugzeitspektroskopie
No full textSpieweck M. Experimentelle Realisierung von frequenzkonvertierter ns-VUV- und fs-EUV-Strahlung für Photoelektronenflugzeitspektroskopie. Bielefeld; 2000
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