1,720,997 research outputs found
1,1,1,2-Tetrafluoroethane (HFC-134a): results from a coupled quantum-chemical investigation and high-resolution FAR IR rovibrational analysis
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Pure rotational spectrum of 15ND and isotopic-independent Dunham-type analysis of imidogen radical
No full textHigh-resolution molecular spectroscopy of open shell molecules: isotopologues of the imidogen (15ND) and amidogen (15ND2) radicals
No full textHigh-resolution molecular spectroscopy of open shell molecules: isotopologues of the imidogen (15ND) and amidogen (15ND2) radicals
Dore Luca 1, Bizzocchi Luca 2, Degli Esposti Claudio 1, Melosso Mattia 1, Tamassia Filippo 3
1 Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via Francesco Selmi 2, I-40126 Bologna, Italy
2 Centre for Astrochemical Studies, Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße 1, D-85749 Garching bei München, Germany
3 Dipartimento di Chimica Industriale “Toso Montanari”, Università di Bologna, Via del Risorgimento 2, I-40136 Bologna, Italy
A wide number of studies have been carried out on the imidogen and amidogen radicals, which are thought to be involved in the ion-reaction scheme in which ammonia is produced from N+. The rotational spectrum of the main isotopologue of the imidogen radical NH has been investigated in the THz region as well as in the Far-Infrared-Region [1]. In addition, the less common isotopologues ND and 15NH have been studied by rotational spectroscopy [2,3,4]. The interest on this small free radical has increased, since both NH and ND have been detected is several astronomical sources [5,6]. However, no data on the rare isotopologue 15ND were available until now. In this work, 15ND radical has been produced by DC-glow discharge of 15ND3 and Ar and its pure rotational spectrum has been recorded up to 1.2 THz. The fine and hyperfine structure of the N = 1 ← 0 and N = 2 ← 1 transitions has been assigned and all the measured line frequencies have been analyzed, allowing to determine the rotational constant B, the centrifugal distortion term D and 9 fine and hyperfine parameters. A global analysis including ro-vibrational data of all the isotopologues of NH radical is in progress. While discharging ammonia, the spectrum of another radical, rapidly identified as 15ND2, appeared (Fig. 1). In fact, imidogen and amidogen radicals are usually obtained in the same conditions. Although the amidogen radical has been subjected to numerous studies [7,8,9], no spectroscopic data on 15ND2 are reported. In the second part of our work, the rotational spectrum of the 15ND2 radical has been observed in selected frequency regions between 264 GHz and 1.2 THz. A total of 164 transitions have been recorded and assigned, whose analysis allowed us to determine with high accuracy the rotational constants, some centrifugal distortion terms and 21 fine and hyperfine parameters.
References:
[1] Flores-Mijangos J. et al., J. Mol. Spectrosc., 225, 189-195 (2004).
[2] Saito S. et al., ApJ., 410, L53-L55, 1993.
[3] Dore L. et al., Mol. Phys., 109, 2191-2198 (2011).
[4] Bailleux S. et al., A&A, 538, A135 (2012).
[5] Meyer M.D. et al., ApJ., 376, L49-L52 (1991).
[6] Bacmann A. et al., A&A, 521, L42 (2010).
[7] Muller H.S.P. et al., J. Mol. Spectro., 195, 177-184 (1999).
[8] Kanada M. et al., AIP, 94, 3423 (1991).
[9] Margulès L. et al., A&A, 591, A110 (2016)
The high -resolution spectrum of DC3N recorded in the infrared and millimeter-wave regions: a global analysis
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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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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