Atomic data for opacity calculations. XVII. Calculation of line broadening parameters and collision strengths between n=2,3 and 4 states in C IV

1992 ◽  
Vol 25 (22) ◽  
pp. 4917-4928 ◽  
Author(s):  
V M Burke
Keyword(s):  
Atomic Data ◽  
Line Broadening

scholarly journals The OPAL opacity Code

1995 ◽  
Vol 10 ◽  
pp. 573-573 ◽  
Author(s):  
F.J. Rogers ◽  
C.A. Iglesias
Keyword(s):  
Equation Of State ◽  
Cross Sections ◽  
Potential Method ◽  
Thomson Scattering ◽  
Mechanical Analysis ◽  
Atomic Data ◽  
Collective Effects ◽  
Line Broadening ◽  
On Line ◽  
Computationally Intensive

The OPAL opacity effort was undertaken in 1985 in response to speculation that the existing opacity data were not of sufficient accuracy to model observed stellar properties. We have taken the view that a completely new code with improved equation of state, atomic physics and line broadening was required. It was apparent that the most computationally intensive part of the calculations would be to obtain the vast amount of atomic data needed for the bound-bound and bound-free absorption cross-sections. To meet this challenge we developed a parametric potential method, that was fast enough to allow on-line calculations, while achieving accuracy comparable to that of the single-configuration Dirac-Fock method. This on-line capability was also chosen to allow flexibility to study the effect of various coupling and data averaging methods. It also makes it easy to study the effect of adding more elements.The OPAL equation of state is based on the many-body statistical mechanics of partially ionized plasmas in the grand canonical ensemble. This is the so-called “physical picture” method. In this approach one works directly with the electrons and nuclei present in the plasma. The effect of the plasma environment on the internal states is obtained directly from the statistical mechanical analysis. A convergent partition function is a natural consequence of this approach.OPAL includes degeneracy and plasma collective effects in the free-free absorption using a screened form of the parametric potentials. Similar corrections to the Thomson scattering are obtained from the method of Boercker (1987). The spectral line broadening for one, two and three electrons ions are obtained from a suite of codes provided by R.W. Lee (1988) that include linear Stark theory. For all other transitions we use Voigt profiles where the Gaussian width is due to Doppler broadening and the Lorentz width is due to the natural width plus fits to the electron impact collision width (Dimitrievic and Konjevic 1980).

scholarly journals Cross Sections and Line-Broadening

1983 ◽  
Vol 6 ◽  
pp. 789-790
Author(s):  
A. Dalgarno
Keyword(s):  
Plasma Physics ◽  
Cross Sections ◽  
Fusion Energy ◽  
National Laboratory ◽  
Molecular Data ◽  
Impact Excitation ◽  
Atomic Data ◽  
List Type ◽  
Line Broadening ◽  
Oak Ridge

Stimulated mostly by the needs of the fusion energy programs, data centres have been established from which information can be obtained on photoionization and recombination processes, electron and ion Impact excitation, ionization and charge transfer cross sections and on electron and proton line-broadening parameters. Regular reports are issued by most of the centres. A partial list follows:(1)Atomic Data for Fusion, Ed. C.F. Barnett, D.H. Crandall and W.L. Wiese: Oak Ridge National Laboratory, P.O. Box X, Bldg, 6003, Oak Ridge, Tenn. 7830, USA.(2)International Bulletin on Atomic and Molecular Data for Fusion, Ed. K. Katsonls: Atomic and Molecular Data Unit, Nuclear Data Section, International Atomic Energy Agency, Wagramerstrasse 5, P.O. Box 100, A-1400 Vienna, Austria.(3)Research Information Center, Institute of Plasma Physics, Nagoya University, Nagoya, Japan, Ed. Y. Itikawa.(4)JAERI Data Center, Division of Plasma Physics, JAERI, 319-11, Tokai-Mura, Japan. K. Ozawa.In addition, Daresbury Laboratory, Science and Engineering Research Council, Daresbury, Warrington WA4 4AD, England, Eds., W. Eissner and C.J. Noble, publishes an Information Quarterly for Atomic Processes and Applications, which reports continuing developments particularly on calculations of electron impact cross sections.

The Interpretation of Solar Spectral Intensities

1988 ◽  
Vol 102 ◽  
pp. 329
Author(s):  
R.W.P. McWhirter
Keyword(s):  
Emission Measure ◽  
Physical Nature ◽  
Atomic Data ◽  
The Sun ◽  
Atomic Properties ◽  
Outer Atmosphere ◽  
Spectral Intensities ◽  
Thin Plasma ◽  
Number Of Authors

The intensity of a specrtal line from an optically thin plasma such as the outer atmosphere of the sun depends on both the atomic properties of the atomic ion responsible for the line and the physical nature of the plasma. In this paper we discuss the various ways in which the measured spectral intensities from the sun are used to discover something about the nature of the sun’s atmosphere. The technique has been referred to as the emission measure method. It has important limitations in terms of the accuracy of the specrtal data as well as the atomic data. We discuss some of these and suggest methods by which they may be assessed. The technique is illustrated by application to real observations from a number of authors.

Recent Radiative and Collisional Atomic Data of Astrophysical Interest

1988 ◽  
Vol 102 ◽  
pp. 129-132
Author(s):  
K.L. Baluja ◽  
K. Butler ◽  
J. Le Bourlot ◽  
C.J. Zeippen
Keyword(s):  
Mass Production ◽  
Bound States ◽  
Physical Models ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Atomic Data ◽  
Isoelectronic Sequence ◽  
Astrophysical Interest ◽  
Radiative Transitions ◽  
Forbidden Transitions

SummaryUsing sophisticated computer programs and elaborate physical models, accurate radiative and collisional atomic data of astrophysical interest have been or are being calculated. The cases treated include radiative transitions between bound states in the 2p4and 2s2p5configurations of many ions in the oxygen isoelectronic sequence, the photoionisation of the ground state of neutral iron, the electron impact excitation of the fine-structure forbidden transitions within the 3p3ground configuration of CℓIII, Ar IV and K V, and the mass-production of radiative data for ions in the oxygen and fluorine isoelectronic sequences, as part of the international Opacity Project.

RECENT RADIATIVE AND COLLISIONAL ATOMIC DATA OF ASTROPHYSICAL INTEREST

1988 ◽  
Vol 49 (C1) ◽  
pp. C1-129-C1-132 ◽  
Author(s):  
K. L. BALUJA ◽  
K. BUTLER ◽  
J. LE BOURLOT ◽  
C. J. ZEIPPEN
Keyword(s):  
Atomic Data ◽  
Astrophysical Interest

Nondestructive Inspection of Thin, Low-Z Samples using Multiplexed Compton Scatter Tomography

1997 ◽  
Vol 503 ◽  
Author(s):  
B. L. Evans ◽  
J. B. Martin ◽  
L. W. Burggraf
Keyword(s):  
Signal To Noise Ratio ◽  
Reconstruction Algorithm ◽  
Filtered Backprojection ◽  
Line Broadening ◽  
Compton Scatter ◽  
X Ray ◽  
Tomography System ◽  
Transmission Computed Tomography ◽  
High Purity Germanium ◽  
Scattered Energy

ABSTRACTThe viability of a Compton scattering tomography system for nondestructively inspecting thin, low Z samples for corrosion is examined. This technique differs from conventional x-ray backscatter NDI because it does not rely on narrow collimation of source and detectors to examine small volumes in the sample. Instead, photons of a single energy are backscattered from the sample and their scattered energy spectra are measured at multiple detector locations, and these spectra are then used to reconstruct an image of the object. This multiplexed Compton scatter tomography technique interrogates multiple volume elements simultaneously. Thin samples less than 1 cm thick and made of low Z materials are best imaged with gamma rays at or below 100 keV energy. At this energy, Compton line broadening becomes an important resolution limitation. An analytical model has been developed to simulate the signals collected in a demonstration system consisting of an array of planar high-purity germanium detectors. A technique for deconvolving the effects of Compton broadening and detector energy resolution from signals with additive noise is also presented. A filtered backprojection image reconstruction algorithm with similarities to that used in conventional transmission computed tomography is developed. A simulation of a 360–degree inspection gives distortion-free results. In a simulation of a single-sided inspection, a 5 mm × 5 mm corrosion flaw with 50% density is readily identified in 1-cm thick aluminum phantom when the signal to noise ratio in the data exceeds 28.

Solvent-Ligand Interactions in Colloidal Nanocrystals

2018 ◽  
Author(s):  
Jonathan De Roo ◽  
Nuri Yazdani ◽  
Emile Drijvers ◽  
Alessandro Lauria ◽  
Jorick Maes ◽  
...  
Keyword(s):  
Direct Method ◽  
Line Broadening ◽  
H Nmr ◽  
Size Dependent ◽  
Line Shape Analysis ◽  
Wide Range ◽  
Nanocrystal Synthesis ◽  
Ligand Interactions ◽  
Indispensable Tool ◽  
Theoretical Evidence

<p>Although solvent-ligand interactions play a major role in nanocrystal synthesis, dispersion formulation and assembly, there is currently no direct method to study this. Here we examine the broadening of <sup>1</sup>H NMR resonances associated with bound ligands, and turn this poorly understood descriptor into a tool to assess solvent-ligand interactions. We show that the line broadening has both a homogeneous and a heterogeneous component. The former is nanocrystal-size dependent and the latter results from solvent-ligand interactions. Our model is supported by experimental and theoretical evidence that correlates broad NMR lines with poor ligand solvation. This correlation is found across a wide range of solvents, extending from water to hexane, for both hydrophobic and hydrophilic ligand types, and for a multitude of oxide, sulfide and selenide nanocrystals. Our findings thus put forward NMR line shape analysis as an indispensable tool to form, investigate and manipulate nanocolloids.</p>

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