1,721,006 research outputs found
The v1 and v3 stretching fundamental bands of PD3
No full textThe infrared (IR) spectrum of PD3 has been recorded in the 1580-1800 cm-1 range at a resolution of 0.0027 cm-1. About 2400 rovibrational transitions with J′ = K′ ≤ 22 have been measured and assigned to the v1 (A1) and v3 (E) stretching fundamentals. These include 506 "perturbation-allowed" transitions with selection rules Δ(k - 1) = ±3. Splitting of the K′′ = 3 lines have been observed. Effects of strong perturbations are evident in the spectrum. Therefore the rovibrational Hamiltonian adopted for the analysis explicity takes into account the Coriolis and k-type interactions between the v1 = 1 and v3 = 1 states, includes also several essential resonances within these states. The rotational structure in the v1 = 1 and v3 = 1 vibrational states up to J′ = K′ = 18 was reproduced by fitting simultaneously all experimental data. Thirty-four parameters reproduced 1950 transitions retained in the final cycle with a standard deviation of the fit equal to 4.9 × 10-4 cm-1 (about the precision of the experimental measurements)
The Si-H Stretching Fundamentals of H328SiD
No full textThe ν1(A1) and ν4(E) Si-H stretching fundamentals of H3SiD have been recorded at an effective resolution of 0.006 cm-1 between 2050 and 2300 cm-1. A total of about 2500 rovibrational transitions of the H328SiD isotopomer have been assigned with J′ up to 27 and K′ up to 22. A large number of "perturbation allowed" Δk = ±3 transitions have been identified in both the ν1 and ν4 bands. The assigned transitions have been analyzed using two different theoretical models, which took into account several rovibrational interactions between and within the ν1 = 1 and ν4 = 1 states, yielding a standard deviation of each fit of ca. 0.0004 cm-1, which may be compared with the experimental precision (ca. 0.0001 cm-1). Improved ground state parameters have also been obtained by means of ground state combination differences. © 1997 Academic Press
The v2 and v4 bending fundamental bands of PD3
No full textInfrared spectra of PD3 have been recorded in the 600-1160 cm-1 range at a resolution of 0.0023 cm-1. About 2500 rovibrational transitions have been measured and assigned to the v2(A1) and v4(E) bending fundamentals, including 131 "perturbation allowed" transitions with selection rules Δ(k-1) = ±3 and ±6. Splittings of the K′′ = 3, 6, and 9 lines were observed. The rotational structure in the v2 = 1 and v4 = 1 vibrational states up to J = K = 28 was reproduced by fitting simultaneously all experimental data. The adopted rovibrational Hamiltonian explicitly takes into account the Coriolis and k-type interactions between the v2 = 1 and v4 = 1 states, and includes also several essential resonances within these states. Two different reductions of the Hamiltonian were adopted in the fitting procedure. The 41 parameters in model 1 reproduced 2435 IR transitions retained in the final cycle with a standard deviation of the fit equal to 2.06 × 10-4 cm-1 (about the precision of experimental measurements); in model 2, 45 parameters reproduced 2428 transitions with the same value of standard deviation. The equivalence of the two sets of parameters has been demonstrated
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
The ground state spectroscopic parameters and equilibrium structure of PD3
No full textInfrared spectra of PD3 have been measured in the 20-320 cm-1 range and in the region of the ν2/ν4 and ν1/ν3 fundamental bands near 750 and 1690 cm-1, respectively, with a resolution of ca. 0.0025 cm-1. Furthermore, submillimeter-wave spectra covering the J = 4-3, 13-12, and 14-13 clusters in the vibrational ground state were recorded. The observed ΔJ = +1 rotational lines were augmented by about 5500 ground state combination differences formed from transitions belonging to the fundamental bands. Of these, 1300 involved perturbation-allowed lines with ΔK ≠ 0. These data and observations taken from the literature were appropriately weighted and fitted to 14 ground state molecular constants. The A and B reductions of the rotational Hamiltonian were found to be equivalent. Improved effective ground state and equilibrium structures were determined for both PH3 and PD3; the equilibrium structures, re (PH) = 141.1607(83) pm and αe (HPH) = 93.4184(95)° and re (PD) = 141.1785(57) pm and αe (DPD) = 93.4252(68)°, are in good agreement. © 2002 Elsevier Science (USA)
Mono- and di-deuterated ammonias: Far-infrared spectra and spectroscopic parameters in the ground state
No full textTransitions of NH2D and ND2H have been detected in the high resolution spectrum of 14ND3 recorded at unapodized resolution of 0.00096 cm−1 in the region 60–600 cm−1 using the Bruker IFS 125 Fourier transform spectrometer located at the synchrotron far-infrared beamline, Canadian Light Source. In this study we report on the observation and analysis of the spectrum for the ground state of NH2D and ND2H. 2153 rotation and rotation-inversion transitions, with J up to 24, were assigned for NH2D, and 3214 transitions, with J up to 28, for ND2H. The newly assigned transitions, together with those present in the literature, were fitted on the basis of a Watson-type S reduced Hamiltonian using the IIIr and IIIl representations for NH2D and ND2H, respectively. The model Hamiltonian includes terms up to the 10th power of the angular momentum and vibration–rotation interaction terms between the inversion states. Precise and extended sets of spectroscopic effective parameters were derived for both isotopologues as results of least squares weighted fit procedures that reproduce the transition wavenumbers at experimental accuracy
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