Identifying the 630 nm auroral arc emission height: A comparison of the triangulation, FAC profile, and electron density methods

2017 ◽  
Vol 122 (8) ◽  
pp. 8181-8197 ◽  
Author(s):  
D. Megan Gillies ◽  
D. Knudsen ◽  
E. Donovan ◽  
B. Jackel ◽  
R. Gillies ◽  
...  
Keyword(s):  
Electron Density ◽  
Density Methods ◽  
Emission Height

scholarly journals The Chemistry of Heteroarylphosphorus Compounds, Part 16.+ An X-Ray Structural Study of (2-Thienyl)bis(2,2′-biphenylylene)phosphorane. A Comparison with Related Methyl and Aryl bis(2,2′-biphenylylene)- spirophosphoranes

1983 ◽  
Vol 38 (4) ◽  
pp. 465-469 ◽  
Author(s):  
David W. Allen ◽  
Lorraine A. March ◽  
Ian W. Nowell ◽  
John C. Tebby
Keyword(s):  
Least Squares ◽  
Electron Density ◽  
Structural Study ◽  
Equatorial Plane ◽  
Title Compound ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Thienyl Group ◽  
Density Methods ◽  
Least Squares Techniques

AbstractCrystals of the title compound are monoclinic, a= 18.9 93 (11), b = 8.757(5), c= 13.267(8) Å, β = 106.60(5)°, Z = 4 in space group Cc (Cs4 , No. 9). The structure was determined by Patterson and electron-density methods and refined by least squares techniques to R= 0.081, R′ = 0.085 for 1293 independent reflections classified as observed. The molecule is found to adopt an almost regular trigonal bipyramidal geometry in which the two biphenylylene units span apical-equatorial positions and the 2-thienyl group occupies the remaining equatorial site. The 2-thienyl group, which is disordered, does not lie in the equatorial plane, and there is no indication of C2pπ → P3dπ-t interactions between the heteroaryl group and phosphorus. The steric requirements of the 2-thienyl group appear to be comparable with those of methyl and phenyl groups in bis(2,2′-biphenylylene)spiro-phosphoranes.

A First Experimental Electron Density Study on a C70 Fullerene: (C70C2F5)10

2010 ◽  
Vol 65 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Roman Kalinowski ◽  
Manuela Weber ◽  
Sergey I. Troyanov ◽  
Carsten Paulmann ◽  
Peter Luger
Keyword(s):  
High Resolution ◽  
Electron Density ◽  
Theoretical Calculations ◽  
Asymmetric Unit ◽  
Data Set ◽  
X Ray ◽  
Atomic Properties ◽  
Density Methods ◽  
Experimental Electron Density ◽  
Density Study

The electron density of the C70 fullerene C70(C2F5)10 was determined from a high-resolution X-ray data set measured with synchrotron radiation (beamline F1 of Hasylab/DESY, Germany) at a temperature of 100 K. With 140 atoms in the asymmetric unit this fullerene belongs to the largest problems examined until now by electron density methods. Using the QTAIM formalism quantitative bond topological and atomic properties have been derived and compared with the results of theoretical calculations on the title compound and on free C70

X-ray Structural Study of 5-Phenyl-10,11-dihydrodibenzo[b,f]phosphepin-5-oxide

1980 ◽  
Vol 35 (2) ◽  
pp. 133-135 ◽  
Author(s):  
David W. Allen ◽  
Ian W. Nowell ◽  
Philip E. Walker
Keyword(s):  
Least Squares ◽  
Electron Density ◽  
Structural Study ◽  
Title Compound ◽  
Bond Distance ◽  
Direct Methods ◽  
X Ray ◽  
Phenyl Rings ◽  
Density Methods ◽  
Least Squares Techniques

AbstractCrystals of the title compound are triclinic, a = 8.533(5), b = 11.106(6), c = 8.815(5) Å, a = 107.83(6), β = 104.99(6), γ = 81.30(5)°, Z = 2, space group P1̄. The structure was determined by multisolution direct methods and electron density methods. Refinement by least-squares techniques gave a final R = 0.081 for the 1753 independent reflections. The molecule adopts a butterfly-type conformation such that the fused phenyl rings are inclined to each other at an angle of 56.8°. The P-0 bond distance is 1.506(4) Å; the endocyclic angle at phosphorus is 107.2(3)° and the exocyclic angles vary from 106.5 to 111.9(3)°.

Crystal Structure of Bis[hexakis(dimethylamino)cyclotriphosphonitrilium] Tetrachlorocobaltate(II)

1974 ◽  
Vol 52 (5) ◽  
pp. 734-737 ◽  
Author(s):  
Alistair L. Macdonald ◽  
James Trotter
Keyword(s):  
Crystal Structure ◽  
Nitrogen Atom ◽  
Least Squares ◽  
Electron Density ◽  
Title Compound ◽  
Full Matrix ◽  
Space Group ◽  
Density Methods ◽  
Protonated Nitrogen Atom ◽  
Hydrogen Bonded

Crystals of the title compound, [N3P3(NMe2)6H]2CoCl4, are orthorhombic, a = 34.623, b = 13.964, c = 10.486 Å, Z = 4, space group P212121. The structure was determined by Patterson and electron-density methods and refined by full-matrix least-squares procedures to R = 0.088 for 2178 observed reflexions. Both rings are slightly non-planar, with three distinct pairs of NP bonds: commencing at the protonated nitrogen atom, 1.68, 1.56, and 1.58 Å. The CoCl42− ion is tetrahedral and is hydrogen bonded to both rings, N—H … Cl = 3.32, 3.36 Å.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Glycogen in guinea pig neutrophils: Ultrastructural study of neutrophils at the intradermal site of BCG injection

1983 ◽  
Vol 41 ◽  
pp. 726-727
Author(s):  
Corazon D. Bucana
Keyword(s):  
Bone Marrow ◽  
Guinea Pig ◽  
Electron Density ◽  
Peritoneal Cavity ◽  
Ultrastructural Study ◽  
Guinea Pigs ◽  
Random Distribution ◽  
Glycogen Content ◽  
Polymorphonuclear Neutrophils ◽  
Ultrastructural Studies

In the circulating blood of man and guinea pigs, glycogen occurs primarily in polymorphonuclear neutrophils and platelets. The amount of glycogen in neutrophils increases with time after the cells leave the bone marrow, and the distribution of glycogen in neutrophils changes from an apparently random distribution to large clumps when these cells move out of the circulation to the site of inflammation in the peritoneal cavity. The objective of this study was to further investigate changes in glycogen content and distribution in neutrophils. I chose an intradermal site because it allows study of neutrophils at various stages of extravasation.Initially, osmium ferrocyanide and osmium ferricyanide were used to fix glycogen in the neutrophils for ultrastructural studies. My findings confirmed previous reports that showed that glycogen is well preserved by both these fixatives and that osmium ferricyanide protects glycogen from solubilization by uranyl acetate.I found that osmium ferrocyanide similarly protected glycogen. My studies showed, however, that the electron density of mitochondria and other cytoplasmic organelles was lower in samples fixed with osmium ferrocyanide than in samples fixed with osmium ferricyanide.

Application of ruthenium red/osmium tetroxide to bacteria, plant and animal tissue

1986 ◽  
Vol 44 ◽  
pp. 54-55
Author(s):  
R. L. Grayson ◽  
N. A. Rechcigl
Keyword(s):  
Electron Microscopy ◽  
Electron Density ◽  
Osmium Tetroxide ◽  
Biological Materials ◽  
Ruthenium Red ◽  
Animal Tissue

Ruthenium red (RR), an inorganic dye was found to be useful in electron microscopy where it can combine with osmium tetroxide (OsO4) to form a complex with attraction toward anionic substances. Although Martinez-Palomo et al. (1969) were one of the first investigators to use RR together with OsO4, our computor search has shown few applications of this combination in the intervening years. The purpose of this paper is to report the results of our investigations utilizing the RR/OsO4 combination to add electron density to various biological materials. The possible mechanisms by which this may come about has been well reviewed by previous investigators (1,3a,3b,4).

A study on α-RuCl3 crystal structure by scanning tunneling microscopy

1989 ◽  
Vol 47 ◽  
pp. 30-31
Author(s):  
H.-J. Cantow ◽  
H. Hillebrecht ◽  
S. Magonov ◽  
H. W. Rotter ◽  
G. Thiele
Keyword(s):  
Crystal Structure ◽  
Density Distribution ◽  
Scanning Tunneling Microscopy ◽  
Electron Density ◽  
Structure Determination ◽  
Electron Density Distribution ◽  
Scanning Tunneling ◽  
Monoclinic Space Group ◽  
Tunneling Microscopy ◽  
X Ray

From X-ray analysis, the conclusions are drawn from averaged molecular informations. Thus, limitations are caused when analyzing systems whose symmetry is reduced due to interatomic interactions. In contrast, scanning tunneling microscopy (STM) directly images atomic scale surface electron density distribution, with a resolution up to fractions of Angstrom units. The crucial point is the correlation between the electron density distribution and the localization of individual atoms, which is reasonable in many cases. Thus, the use of STM images for crystal structure determination may be permitted. We tried to apply RuCl3 - a layered material with semiconductive properties - for such STM studies. From the X-ray analysis it has been assumed that α-form of this compound crystallizes in the monoclinic space group C2/m (AICI3 type). The chlorine atoms form an almost undistorted cubic closed package while Ru occupies 2/3 of the octahedral holes in every second layer building up a plane hexagon net (graphite net). Idealizing the arrangement of the chlorines a hexagonal symmetry would be expected. X-ray structure determination of isotypic compounds e.g. IrBr3 leads only to averaged positions of the metal atoms as there exist extended stacking faults of the metal layers.

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