1,721,010 research outputs found
SAND IN THE LABORATORY. PRODUCTION AND INTERROGATION OF GAS PHASE SILICATES.
Get PDFGiven its technological importance, the literature abounds with models for plasma enhanced chemical vapor deposition of the SiH/O/Ar system. In a continuing effort to identify and characterize the optical spectra of Si generated in a SiH/Ar pulsed discharge sourcefootnote{The electronic spectrum of Si I: the triplet D system� Reilly, N. J.; Kokkin, D. L.; Zhuang, X.; Gupta, V.; Nagarajan, R.; Fortenberry, R. C.; Maier, J. P.; Steimle, T. C.; Stanton, J. F.; McCarthy, M. C., J. Chem. Phys. 136(19), 194307, 2012.}, we detected, via two dimensional (2D) LIF, a relatively strong electronic transition in the 570-600,nm region that is strongly enhanced by the addition of a small amount of O. The excitation spectrum shows resolved band structure at the pulsed laser resolution of 0.5,cm and exhibits a radiative lifetime of 1.97,s. The dispersed fluorescence exhibits three vibrational progressions and an unusually small splitting of approximately 50,cm. Here we report on efforts to identify the molecular carrier of these bands, with particular interest paid to species resulting from oxygen impurities in the silane discharge.Made available in DSpace on 2016-01-05T20:06:36Z (GMT). No. of bitstreams: 3
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Previous issue date: 2
Application of two dimensional flourescence spectroscopy to transition metal clusters
Get PDF\begin{wrapfigure}{r}{0pt}
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Determining the physical properties (bond lengths, angles, dipole moments, etc) of transition metal oxides and dioxides is relevant to catalysis, high temperature chemistry, materials science and astrophysics. Analysis of optical spectra is a convenient method for extraction of physical properties, but can be difficult because of the density of electronic states and in the case of the dioxides, presence of both the oxide and superoxide forms. Here we demonstrate the application of two dimensional fluorescence spectroscopy\footnote{N.J. Reilly, T.W. Schmidt, S.H. Kable, \textit{J. Phys. Chem. A.}, 110(45), 12355-12359, 2006} for aiding in the assignment and analysis. Particular attention will be paid to the spectroscopy of first row transition metal monoxides and dioxides of Nickel, NiO and NiO, and Manganese, MnO. Furthermore, the application of this technique to discovering the spectrum of other transition metal systems such as Metal-dicarbides will be outlined.Made available in DSpace on 2014-09-17T16:55:42Z (GMT). No. of bitstreams: 3
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Previous issue date: 2014-06-17Made available in DSpace on 2015-04-14T18:37:36Z (GMT). No. of bitstreams: 4
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Previous issue date: 2014-06-1
Optical stark spectroscopy of gold chloride
Get PDFThe bonding and electrostatic properties of gold containing molecules are highly influenced by relativistic effects and electron correlation \footnote{P. Pyykko; \textit {Angew Chem. Int} {\textbf{43}} 4412, 2004.}. Hence it is difficult to predict those properties via electron structure calculation, and such calculation are guided by experimental observations. Here we report on the and bands of \chem{AuCl}, which have been previously recorded at Doppler limited resolution \footnote{L. C. O’Brien, A. L. Elliott, and M. Dulick; \textit {J. Mol. Spectrosc} {\textbf{194}} 124, 1999.}. A cold molecular beam sample was generated and the bands were recorded at high resolution (FWHM =35 MHz) using laser excitation spectroscopy, both field-free and in the presence of a static electric field. An improved set of spectroscopic parameters for the and states were obtained. The Stark induced shifts were analyzed to determine the permanent electric dipole moments for the X, A, and B states. A comparison with \chem{AuF} \footnote{T. C. Steimle, R. Zhang, C. Qin and T. D. Varberg; \textit {J. Phys. Chem. A} {\textbf{117(46)}} 11739,2013.} and theory will be made.Made available in DSpace on 2014-09-17T16:55:49Z (GMT). No. of bitstreams: 3
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Previous issue date: 2014-06-17Made available in DSpace on 2015-04-14T18:43:04Z (GMT). No. of bitstreams: 4
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Previous issue date: 2014-06-1
Stark and zeeman effect in the [18.5]2∆ 3/2 - X2∆3/2 transition of thorium monofluoride
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Previous issue date: 6Made available in DSpace on 2018-12-12T22:37:38Z (GMT). No. of bitstreams: 4
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Previous issue date: 6Studies of the bonding and electronic structure of simple actinide compoundsbcde are attractive because they provide insight into the chemistry of more complex molecules associated with radioactive waste. These molecules are the most effective venues for developing a synergism between theory and experiment. The primary goal of the present study is to understand and identify different levels of covalency in a series of gas phase actinides and lanthanides containing molecules via the determination of the permanent electric dipole moment, µ, and magnetic g-factors. The electronic spectrum of ThF has been investigated using: a) medium resolution two dimensional (2D)f ; ultrahigh field free, Stark, and Zeeman spectroscopy of a supersonically cooled molecular beam sample. A strong band system near 540 nm was detected and the Stark shifts and splitting were analyzed to produce µ values of 1.426(18)D and 0.586(30)D, for the X2∆3/2 and [18.5] Ω=3/2 states, respectively. Zeeman splittings were analyzed to show that both the ground and excited [18.5] Ω=3/2 states are predominately 2∆3/2 spin-orbit components. A molecular orbital correlation diagram will be used to rationalize the observed very small µ values, the electronic state distribution, and garner insight into the bonding mechanism
STARK AND ZEEMAN EFFECT IN THE [18.5]2∆ 3/2 - X2∆3/2 TRANSITION OF THORIUM MONOFLUORIDE
No full textStudies of the bonding and electronic structure of simple actinide compounds\footnote{M. C. Heaven, B. J. Barker and I. O. Antonov, J. Phys. Chem. A, 2014, 118, 10867-10881.}\footnote{T. Steimle, D. L. Kokkin, S. Muscarella and T. Ma, J. Phys. Chem. A, 2015, 119, 9281-9285.}\footnote{C. Linton, A. G. Adam and T. C. Steimle, J. Chem. Phys., 2014, 140, 214305/214301-214305/214307.}\footnote{D. L. Kokkin, T. C. Steimle and D. DeMille, Phys. Rev. A: At., Mol., Opt. Phys., 2014, 90, 062503/062501-062503/062510.} are attractive because they provide insight into the chemistry of more complex molecules associated with radioactive waste. These molecules are the most effective venues for developing a synergism between theory and experiment. The primary goal of the present study is to understand and identify different levels of covalency in a series of gas phase actinides and lanthanides containing molecules via the determination of the permanent electric dipole moment, , and magnetic g-factors. The electronic spectrum of ThF has been investigated using: a) medium resolution two dimensional (2D)\footnote{N. J. Reilly, T. W. Schmidt and S. H. Kable, J. Phys. Chem. A, 2006, 110, 12355-12359.}; ultrahigh field free, Stark, and Zeeman spectroscopy of a supersonically cooled molecular beam sample. A strong band system near 540 nm was detected and the Stark shifts and splitting were analyzed to produce values of 1.426(18)D and 0.586(30)D, for the X and [18.5] =3/2 states, respectively. Zeeman splittings were analyzed to show that both the ground and excited [18.5] =3/2 states are predominately spin-orbit components. A molecular orbital correlation diagram will be used to rationalize the observed very small values, the electronic state distribution, and garner insight into the bonding mechanism
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
Molecular beam optical study of gold sulfide and gold oxide
Get PDFGold-sulfur and gold-oxygen bonds are key components to numerous established and emerging technologies that have applications as far ranging as medical imaging, catalysis, electronics, and material science. A major theoretical challenge for describing this bonding is correctly accounting for the large relativistic and electron correlation effects. Such effects are best studied in diatomic, AuX, molecules. Recently, the observed AuS electronic state energy ordering was measured and compared to a simple molecular orbital
diagram prediction\footnote{D. L. Kokkin, R. Zhang, T. C. Steimle, I. A. Wyse, B. W. Pearlman and T. D. Varberg, \textit {J. Phys. Chem. A.}, {\textbf{119(48)}}, 4412, 2015.}. Here we more thoroughly investigate the nature of the electronic states of both AuS and AuO from the analysis of high-resolution (FWHMMHz) optical Zeeman spectroscopy of the (0,0)\textit {B}\textit {X} bands. The determined fine and hyperfine parameters for the \textit {B} state of AuO differ from those extracted from the analysis of a hot, Doppler-limited, spectrum\footnote{L. C. O'Brien, B. A. Borchert, A. Farquhar, S. Shaji, J. J. O'Brien and R. W. Field, \textit {J. Mol. Spectrosc.}, {\textbf{252(2)}}, 136, 2008.}. It is demonstrated that the nature of the \textit {B} states of AuO and AuS are radically different. The magnetic tuning of AuO and AuS indicates that the \textit {B} states are heavily contaminated.Made available in DSpace on 2017-01-26T21:39:46Z (GMT). No. of bitstreams: 3
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Previous issue date: 2016-06-2
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
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