Generalized ellipsometry and dielectric tensor of rubrene single crystals

2007 ◽  
Vol 102 (2) ◽  
pp. 023107 ◽  
Author(s):  
S. Tavazzi ◽  
L. Silvestri ◽  
M. Campione ◽  
A. Borghesi ◽  
A. Papagni ◽  
...  
Keyword(s):  
Single Crystals ◽  
Dielectric Tensor

scholarly journals Dielectric tensor of monoclinic Ga2O3 single crystals in the spectral range 0.5–8.5 eV

APL Materials ◽  
2015 ◽  
Vol 3 (10) ◽  
pp. 106106 ◽  
Author(s):  
C. Sturm ◽  
J. Furthmüller ◽  
F. Bechstedt ◽  
R. Schmidt-Grund ◽  
M. Grundmann
Keyword(s):  
Single Crystals ◽  
Spectral Range ◽  
Dielectric Tensor

Ellipsometric Study of Anisotropy Permittivity of Hexagonal Manganites RMnO3 (R = Ho, Tm, Yb)

2012 ◽  
Vol 190 ◽  
pp. 273-276 ◽  
Author(s):  
A.A. Makhnev ◽  
L.V. Nomerovannaya ◽  
Natalia N. Loshkareva ◽  
A.M. Balbashov
Keyword(s):  
Single Crystals ◽  
Absorption Edge ◽  
Near Infrared ◽  
Fundamental Absorption Edge ◽  
Dielectric Tensor ◽  
Broad Absorption ◽  
Intense Band ◽  
Broad Absorption Band ◽  
Ellipsometric Study ◽  
Hexagonal Manganites

The optical properties of single crystals of the hexagonal manganites RMnO3 (R = Ho, Tm, Yb) have been investigated by spectroscopic ellipsometry in the spectral range 0.6-5.0 eV. The measurements show a strong anisotropy of the diagonal elements of the dielectric tensor. It has been demonstrated that the optical absorption edge for the polarization Ec was determined by the intense band of O(2p)Mn (3d) transition centered near 1.6 eV, whereas this band for the polarization Ec was strongly suppressed and shifted toward higher energies by 0.15-0.20 eV. The spectral dependences of the ε1(E) and ε2(E) for HoMnO3, TmMnO3 and YbMnO3 single crystals were qualitatively similar. The broad absorption band at E<1.0 eV clearly appears at the energies below the fundamental absorption edge of all of study compounds. It is possible, the origin of the near-infrared ε2(E) absorption is associated with 4f-4f transitions of R3+ ions.

scholarly journals Temperature dependence of the dielectric tensor of monoclinic Ga2O3 single crystals in the spectral range 1.0–8.5 eV

2017 ◽  
Vol 111 (8) ◽  
pp. 082102 ◽  
Author(s):  
C. Sturm ◽  
R. Schmidt-Grund ◽  
V. Zviagin ◽  
M. Grundmann
Keyword(s):  
Temperature Dependence ◽  
Single Crystals ◽  
Spectral Range ◽  
Dielectric Tensor

scholarly journals Polarized IR reflectance spectroscopy methods for the orientation of monoclinic single crystals: Tutton salts as a case example

2014 ◽  
Vol 33 (1) ◽  
pp. 27 ◽  
Author(s):  
Vladimir Ivanovski
Keyword(s):  
Single Crystals ◽  
Reflectance Spectra ◽  
Dielectric Tensor ◽  
Cross Polarization ◽  
Crystal Axis ◽  
X Ray ◽  
Principal Axes ◽  
Ir Reflectance ◽  
Ray Methods ◽  
Low Symmetry

Investigation of polarized IR reflectance spectra of single crystals is important in the course of obtaining vibrational, optical and dielectric properties of solid state samples.  Diffraction X-ray methods are usually employed for crystal orientation. In this work, two IR reflectance methods are proposed as a supplement in testing the orientation of the <em>b</em> crystal axis and by that the <em>ac</em> crystal plane, in respect to the morphology of monoclinic single crystals. The methods were tested on two Tutton salt single crystals: K<sub>2</sub>Ni(SO<sub>4</sub>)<sub>2</sub>·6H<sub>2</sub>O and K<sub>2</sub>Ni(SeO<sub>4</sub>)<sub>2</sub>·6H<sub>2</sub>O and were further compared with the cross-polarization IR reflectance method. Both methods rely on the symmetry and optical properties of monoclinic single crystals. One of them takes into account the fact that one of the principal axes of the dielectric tensor is symmetry fixed, while the other employs the conditions for the appearance of an isosbestic-like point i.e. isosbestic-like region in the polarized IR reflectance spectra of single crystals with low symmetry.

Dielectric tensor of tetracene single crystals: The effect of anisotropy on polarized absorption and emission spectra

2008 ◽  
Vol 128 (15) ◽  
pp. 154709 ◽  
Author(s):  
S. Tavazzi ◽  
L. Raimondo ◽  
L. Silvestri ◽  
P. Spearman ◽  
A. Camposeo ◽  
...  
Keyword(s):  
Single Crystals ◽  
Emission Spectra ◽  
Dielectric Tensor ◽  
Absorption And Emission ◽  
Absorption And Emission Spectra

The Microstructure of Shock-Synthesized Diamond

1967 ◽  
Vol 25 ◽  
pp. 324-325
Author(s):  
Lucien F. Trueb
Keyword(s):  
Single Crystals ◽  
Preferred Orientation ◽  
High Magnification ◽  
Texture Pattern ◽  
Shock Process ◽  
New Type ◽  
Diffraction Diagram

A new type of synthetic industrial diamond formed by an explosive shock process has been recently developed by the Du Pont Company. This material consists of a mixture of two basically different forms, as shown in Figure 1: relatively flat and compact aggregates of acicular crystallites, and single crystals in the form of irregular polyhedra with straight edges.Figure 2 is a high magnification micrograph typical for the fibrous aggregates; it shows that they are composed of bundles of crystallites 0.05-0.3 μ long and 0.02 μ. wide. The selected area diffraction diagram (insert in Figure 2) consists of a weak polycrystalline ring pattern and a strong texture pattern with arc reflections. The latter results from crystals having preferred orientation, which shows that in a given particle most fibrils have a similar orientation.

A New Defect in Polyethylene Single Crystals

1973 ◽  
Vol 31 ◽  
pp. 70-71
Author(s):  
E. L. Thomas ◽  
S. L. Sass
Keyword(s):  
Single Crystals ◽  
Screw Dislocation ◽  
Small Distance ◽  
Dipole Model ◽  
Dislocation Dipole ◽  
Chain Folding ◽  
Black And White ◽  
Polymer Crystal ◽  
Different Types

In polyethylene single crystals pairs of black and white lines spaced 700-3,000Å apart, parallel to the [100] and [010] directions, have been identified as microsector boundaries. A microsector is formed when the plane of chain folding changes over a small distance within a polymer crystal. In order for the different types of folds to accommodate at the boundary between the 2 fold domains, a staggering along the chain direction and a rotation of the chains in the plane of the boundary occurs. The black-white contrast from a microsector boundary can be explained in terms of these chain rotations. We demonstrate that microsectors can terminate within the crystal and interpret the observed terminal strain contrast in terms of a screw dislocation dipole model.

Preferential Sputtering of Ni3Al Single Crystals Studied Using Atom-Probe Field-Ion Microscopy and XPS

1981 ◽  
Vol 39 ◽  
pp. 16-17
Author(s):  
M.P. Thomas ◽  
A.R. Waugh ◽  
M.J. Southon ◽  
Brian Ralph
Keyword(s):  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Surface Composition ◽  
Depth Profiling ◽  
Analytical Techniques ◽  
Atom Probe ◽  
Probe Field ◽  
Preferential Sputtering ◽  
Argon Ion Bombardment ◽  
Argon Ion

It is well known that ion-induced sputtering from numerous multicomponent targets results in marked changes in surface composition (1). Preferential removal of one component results in surface enrichment in the less easily removed species. In this investigation, a time-of-flight atom-probe field-ion microscope A.P. together with X-ray photoelectron spectroscopy XPS have been used to monitor alterations in surface composition of Ni3Al single crystals under argon ion bombardment. The A.P. has been chosen for this investigation because of its ability using field evaporation to depth profile through a sputtered surface without the need for further ion sputtering. Incident ion energy and ion dose have been selected to reflect conditions widely used in surface analytical techniques for cleaning and depth-profiling of samples, typically 3keV and 1018 - 1020 ion m-2.

Dislocation structures around SiO2 Particles in aged Cu-Cr-SiO2

1978 ◽  
Vol 36 (1) ◽  
pp. 594-595
Author(s):  
N.J. Long ◽  
M.H. Loretto ◽  
C.H. Lloyd
Keyword(s):  
Flow Stress ◽  
Single Crystals ◽  
Room Temperature ◽  
Thin Foil ◽  
Age Hardening ◽  
Dispersion Strengthening ◽  
Accurate Picture ◽  
The Matrix ◽  
Very High ◽  
Good Agreement

IntroductionThere have been several t.e.m. studies (1,2,3,4) of the dislocation arrangements in the matrix and around the particles in dispersion strengthened single crystals deformed in single slip. Good agreement has been obtained in general between the observed structures and the various theories for the flow stress and work hardening of this class of alloy. There has been though some difficulty in obtaining an accurate picture of these arrangements in the case when the obstacles are large (of the order of several 1000's Å). This is due to both the physical loss of dislocations from the thin foil in its preparation and to rearrangement of the structure on unloading and standing at room temperature under the influence of the very high localised stresses in the vicinity of the particles (2,3).This contribution presents part of a study of the Cu-Cr-SiO2 system where age hardening from the Cu-Cr and dispersion strengthening from Cu-Sio2 is combined.

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