Crystal Structure of Solid Hydrogen and Deuterium, and of Neon—Hydrogen and Neon—Deuterium Mixtures

1966 ◽  
Vol 45 (3) ◽  
pp. 834-837 ◽  
Author(s):  
Charles S. Barrett ◽  
Lothar Meyer ◽  
Judith Wasserman
Keyword(s):  
Crystal Structure ◽  
Solid Hydrogen

Crystal Structure of Solid Hydrogen Chloride and Deuterium Chloride

Nature ◽  
1967 ◽  
Vol 213 (5072) ◽  
pp. 171-172 ◽  
Author(s):  
E. SÁNDOR ◽  
R. F. C. FARROW
Keyword(s):  
Crystal Structure ◽  
Hydrogen Chloride ◽  
Solid Hydrogen ◽  
Deuterium Chloride

The crystal structure of solid hydrogen

1962 ◽  
Vol 1 (1) ◽  
pp. 22-23 ◽  
Author(s):  
J. Van Kranendonk ◽  
H.P. Gush
Keyword(s):  
Crystal Structure ◽  
Solid Hydrogen

The Fundamental Infrared Absorption Band of Ortho-Enriched Solid Hydrogen

1972 ◽  
Vol 50 (18) ◽  
pp. 2063-2073 ◽  
Author(s):  
S. A. Boggs ◽  
M. J. Clouter ◽  
H. L. Welsh
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Rotational Transition ◽  
Solid Hydrogen ◽  
Low Energy ◽  
Side Band ◽  
Disorder Phase Transition ◽  
Orientational Ordering ◽  
Ordered State ◽  
Orientational Transitions

Spectra of the infrared fundamental band of solid hydrogen with orthohydrogen concentrations in the range 75 to ~99% were recorded at 1.05 and ~5 K, i.e. below and above the order–disorder phase transition which occurs at 2.8 K for pure o-H2. The effect of "impurity" para molecules in the o-H2 lattice could thus be studied with and without orientational ordering of the o-H2 molecules. The zero-phonon Q1, S1(0), and S1(1) features are of particular interest, and are interpreted in terms of travelling vibrational, rotational, and orientational excitations (vibrons, rotons, and librons). The Q branch for ~100% o-H2 in the ordered state shows a structured side band, shifted by ~6–26 cm−1 from the Q1(1) frequency and due to one- and two-libron excitations; in the disordered state this becomes a Boltzmann-modified band of half-width 12 cm−1, centered at the Q1(1) frequency, and due to predominantly low-energy orientational transitions of interacting o-H2 molecules. The S1(0) group of maxima in the ordered state is interpreted as the superposition of the transitions, Q1(1) + S0(0) and Q1(1) + S0(0) + libron, where Q1(1) is an o-H2 vibron and S0(0) is the localized rotational transition of an impurity p-H2 molecule, the J = 2 level of which is split into three sublevels by the C3i field of the Pa3 crystal structure.

Crystal structure of high-pressure phase-IV solid hydrogen sulfide

1998 ◽  
Vol 57 (10) ◽  
pp. 5699-5703 ◽  
Author(s):  
S. Endo ◽  
A. Honda ◽  
K. Koto ◽  
O. Shimomura ◽  
T. Kikegawa ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Hydrogen Sulfide ◽  
Solid Hydrogen ◽  
High Pressure Phase ◽  
Pressure Phase ◽  
Phase Iv

Crystal Structure Determination of Glycerol-Containing Lipids from Electron Diffraction Data. Use of Analog Compounds Based upon Configurational Isomers of Cyclopentane-1, 2, 3-TRIOL

1977 ◽  
Vol 35 ◽  
pp. 24-25
Author(s):  
Douglas L. Dorset ◽  
Anthony J. Hancock
Keyword(s):  
Crystal Structure ◽  
Electron Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Crystal Surface ◽  
Coherent Scattering ◽  
Crystal Structure Determination ◽  
Electron Diffraction Data ◽  
Polar Group ◽  
Axis Orientation

Lipids containing long polymethylene chains were among the first compounds subjected to electron diffraction structure analysis. It was only recently realized, however, that various distortions of thin lipid microcrystal plates, e.g. bends, polar group and methyl end plane disorders, etc. (1-3), restrict coherent scattering to the methylene subcell alone, particularly if undistorted molecular layers have well-defined end planes. Thus, ab initio crystal structure determination on a given single uncharacterized natural lipid using electron diffraction data can only hope to identify the subcell packing and the chain axis orientation with respect to the crystal surface. In lipids based on glycerol, for example, conformations of long chains and polar groups about the C-C bonds of this moiety still would remain unknown.One possible means of surmounting this difficulty is to investigate structural analogs of the material of interest in conjunction with the natural compound itself. Suitable analogs to the glycerol lipids are compounds based on the three configurational isomers of cyclopentane-1,2,3-triol shown in Fig. 1, in which three rotameric forms of the natural glycerol derivatives are fixed by the ring structure (4-7).

Spherulitic crystal growth in the prodissoconch larval of Crassostrea virginica

1983 ◽  
Vol 41 ◽  
pp. 518-519
Author(s):  
George G. Cocks ◽  
Louis Leibovitz ◽  
DoSuk D. Lee
Keyword(s):  
Crystal Structure ◽  
Crassostrea Virginica ◽  
Crystal Orientation ◽  
Developmental Changes ◽  
Gastrula Stage ◽  
Orthorhombic Crystal ◽  
Orthorhombic Crystal Structure ◽  
Stages Of Growth ◽  
Early Stages ◽  
Initial Deposition

Our understanding of the structure and the formation of inorganic minerals in the bivalve shells has been considerably advanced by the use of electron microscope. However, very little is known about the ultrastructure of valves in the larval stage of the oysters. The present study examines the developmental changes which occur between the time of conception to the early stages of Dissoconch in the Crassostrea virginica(Gmelin), focusing on the initial deposition of inorganic crystals by the oysters.The spawning was induced by elevating the temperature of the seawater where the adult oysters were conditioned. The eggs and sperm were collected separately, then immediately mixed for the fertilizations to occur. Fertilized animals were kept in the incubator where various stages of development were stopped and observed. The detailed analysis of the early stages of growth showed that CaCO3 crystals(aragonite), with orthorhombic crystal structure, are deposited as early as gastrula stage(Figuresla-b). The next stage in development, the prodissoconch, revealed that the crystal orientation is in the form of spherulites.

Transmission Electron Microscopy studies of the vacancy ordering in YSI2-X thin films

1991 ◽  
Vol 49 ◽  
pp. 562-563
Author(s):  
F.-R. Chen ◽  
T. L. Lee ◽  
L. J. Chen
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Thin Films ◽  
Diffraction Pattern ◽  
Annealing Temperature ◽  
Lattice Mismatch ◽  
Si Substrate ◽  
Metal Thin Films ◽  
Transmission Electron ◽  
Vacancy Ordering

YSi2-x thin films were grown by depositing the yttrium metal thin films on (111)Si substrate followed by a rapid thermal annealing (RTA) at 450 to 1100°C. The x value of the YSi2-x films ranges from 0 to 0.3. The (0001) plane of the YSi2-x films have an ideal zero lattice mismatch relative to (111)Si surface lattice. The YSi2 has the hexagonal AlB2 crystal structure. The orientation relationship with Si was determined from the diffraction pattern shown in figure 1(a) to be and . The diffraction pattern in figure 1(a) was taken from a specimen annealed at 500°C for 15 second. As the annealing temperature was increased to 600°C, superlattice diffraction spots appear at position as seen in figure 1(b) which may be due to vacancy ordering in the YSi2-x films. The ordered vacancies in YSi2-x form a mesh in Si plane suggested by a LEED experiment.

Crystal Structure Analysis of Cu-Zr Alloys by Convergent Beam Diffraction

1981 ◽  
Vol 39 ◽  
pp. 354-355
Author(s):  
A. F. Marshall ◽  
J. W. Steeds ◽  
D. Bouchet ◽  
S. L. Shinde ◽  
R. G. Walmsley
Keyword(s):  
Crystal Structure ◽  
Point Group ◽  
Intermetallic Phase ◽  
Three Dimensional ◽  
Crystal Structure Analysis ◽  
Ion Milling ◽  
Composition And Structure ◽  
Unit Cells ◽  
Sputter Deposited ◽  
Convergent Beam

Convergent beam electron diffraction is a powerful technique for determining the crystal structure of a material in TEM. In this paper we have applied it to the study of the intermetallic phases in the Cu-rich end of the Cu-Zr system. These phases are highly ordered. Their composition and structure has been previously studied by microprobe and x-ray diffraction with sometimes conflicting results.The crystalline phases were obtained by annealing amorphous sputter-deposited Cu-Zr. Specimens were thinned for TEM by ion milling and observed in a Philips EM 400. Due to the large unit cells involved, a small convergence angle of diffraction was used; however, the three-dimensional lattice and symmetry information of convergent beam microdiffraction patterns is still present. The results are as follows:1) 21 at% Zr in Cu: annealed at 500°C for 5 hours. An intermetallic phase, Cu3.6Zr (21.7% Zr), space group P6/m has been proposed near this composition (2). The major phase of our annealed material was hexagonal with a point group determined as 6/m.

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