Modal Composition of the SiC Surface Electromagnetic Response to the External Radiation at Lattice Resonant Frequency

2010 ◽  
Vol 645-648 ◽  
pp. 547-550
Author(s):  
Dmitry Kazantsev
Keyword(s):  
Crystal Surface ◽  
Sample Surface ◽  
Electromagnetic Response ◽  
External Radiation ◽  
Surface Polariton ◽  
Environmental Media ◽  
Polariton Wave ◽  
Excited Wave ◽  
Vector Projection ◽  
Infinite Crystal

To observe the direction of the surface polariton wave excited by the external radiation on the semi-infinite crystal surface, the opaque mask was placed onto the sample surface. The penetration of the surface polariton wave from the open surface in beneath the metal mask was observed via small openings in the mask. It was shown that despite the k-vector mismatch between the surface polariton states and the light in the environmental media (vacuum), non-zero efficiency of the surface wave excitation is still present and that the k-vector of the excited wave corresponds to the k-vector projection of the driving light.

scholarly journals In Situ Electric-Field Study of Surface Effects in Domain Engineered Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 Relaxor Crystals by Grazing Incidence Diffraction

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 728
Author(s):  
Markys G. Cain ◽  
Margo Staruch ◽  
Paul Thompson ◽  
Christopher Lucas ◽  
Didier Wermeille ◽  
...  
Keyword(s):  
Electric Field ◽  
Crystal Surface ◽  
Grazing Incidence ◽  
Sample Surface ◽  
X Ray Diffraction ◽  
Near Surface ◽  
Unit Cells ◽  
Lattice Planes ◽  
Sweet Spots

In this work, we present a grazing incidence X-ray diffraction study of the surface of a 0.24Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) [011] poled rhombohedral single crystal. The near surface microstructure (the top several tens to hundreds of unit cells) was measured in situ under an applied electric field. The strains calculated from the change in lattice parameters have been compared to the macroscopic strain measured with a strain gauge affixed to the sample surface. The depth dependence of the electrostrain at the crystal surface was investigated as a function of temperature. The analysis revealed hidden sweet spots featuring unusually high strains that were observed as a function of depth, temperature and orientation of the lattice planes.

Nonlinear Electrodynamic and Optical Properties of Graphene

2011 ◽  
Vol 324 ◽  
pp. 237-240
Author(s):  
Sergey A. Mikhailov
Keyword(s):  
Optical Properties ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Nonlinear Susceptibility ◽  
Electromagnetic Response ◽  
Nonlinear Electrodynamic ◽  
External Radiation ◽  
Strongly Nonlinear ◽  
Mixing Effects ◽  
New Material

Graphene is a recently discovered new material with unique physical properties. In this paper we discuss its electrodynamic and optical properties. It is shown that the electromagnetic response of graphene to the external radiation is strongly nonlinear and such phenomena as the frequency harmonics generation and frequency mixing effects can be observed in it. The nonlinear susceptibility of graphene is higher than that of many other materials.We predict that under certain conditions the plasmon enhanced second harmonic generation can be observed in graphene.

SURFACE PHONON–POLARITON MODES OF WURTZITE STRUCTURE InN SEMI-INFINITE CRYSTAL

2009 ◽  
Vol 16 (03) ◽  
pp. 355-358 ◽  
Author(s):  
S. S. NG ◽  
Z. HASSAN ◽  
H. ABU HASSAN
Keyword(s):  
Dispersion Curve ◽  
Indium Nitride ◽  
Experimental Information ◽  
Attenuated Total Reflection ◽  
Reflection Method ◽  
Surface Polariton ◽  
Surface Phonon ◽  
Infinite Crystal ◽  
Surface Phonon Polariton ◽  
Anisotropy Model

In this paper, theoretical study on the surface phonon–polariton (SPP) modes of wurtzite (α-) structure indium nitride ( InN ) semi-infinite crystal is presented. Based on an anisotropy model, the surface polariton (SP) dispersion curve of α- InN is simulated. The characteristics of this dispersion curve are discussed. The relevant experimental information by attenuated total reflection method is given. For comparison, the SP dispersion curve of cubic (β-) structure InN simulated based on isotropy model is also presented. Due to optical anisotropic, the SP dispersion curve of α- InN exhibits an extra branch as well as an extra SPP mode as compared to α- InN . In addition, the SPP mode of α- InN is found to be 4 cm-1 smaller than that of β- InN .

Identification of dislocations on crystal surfaces

1988 ◽  
Vol 46 ◽  
pp. 688-689
Author(s):  
L.-M. Peng ◽  
J.M. Cowley ◽  
Tung Hsu
Keyword(s):  
Displacement Field ◽  
Surface Stress ◽  
Strain Field ◽  
Crystal Surface ◽  
Crystal Surfaces ◽  
Burgers Vector ◽  
Infinite Crystal ◽  
Reflection Electron Microscopy ◽  
Electron Imaging ◽  
Ideal Method

A dislocation, when meeting an external crystal surface, will result in the re-arrangement of surface atoms because of the strain field associated with it. For a free surface further complication comes from the requirement that no forces can act on the surface. The displacement field is then a superposition of the displacement field from the dislocation in an infinite crystal and from the surface stress relaxation that cancels the stress field from the dislocation on the surface. The general case for a straight dislocation of arbitrary Burgers vector and arbitrary emerging angle in a semi-infinite, elastically isotopic medium has been solved by Yoffe, and this general solution has been used in our calculations.In the technique of reflection electron microscopy (REM) an electron beam is incident on the surface. The reflection electron imaging is extremely sensitive to any deviation from a perfect surface, and therefore provides a ideal method of observing the surface dislocations.

scholarly journals Compressive strain formation in surface-damaged crystals

2020 ◽  
Vol 53 (3) ◽  
pp. 629-634 ◽  
Author(s):  
Claudio Ferrari ◽  
Sara Beretta ◽  
Enzo Rotunno ◽  
Dusan Korytár ◽  
Zdenko Zaprazny
Keyword(s):  
Crystal Surface ◽  
Compressive Strain ◽  
Sample Surface ◽  
Dislocation Network ◽  
Mechanism Of Formation ◽  
Abrasive Particles ◽  
Transmission Electron ◽  
Proposed Model ◽  
Damaged Zone ◽  
Measured Strain

The mechanism of formation of residual strain in crystals with a damaged surface has been studied by transmission electron microscopy in GaAs wafers ground with sandpaper. The samples showed a dislocation network located near the sample surface penetrating to a depth of a few micrometres, comparable to the size of abrasive particles used for the treatment, and no other types of defects were observed. A simple model for the formation of a compressive strain induced by the dislocation network in the damaged layer is proposed, in satisfactory agreement with the measured strain. The strain is generated by the formation of dislocation half-loops at the crystal surface, having the same component of the Burgers vectors parallel to the surface of the crystal. This is equivalent to the insertion of extra half-planes from the crystal surface to the depth of the damaged zone. This model can be generalized for other crystal structures. An approximate calculation of the strain generated from the observed dislocation distribution in the sample agrees with the proposed model and permits the conclusion that this mechanism is in general sufficient to explain the observed compressive strain, without the need to consider other types of defects.

Convergent Beam Electron Diffraction

1978 ◽  
Vol 36 (3) ◽  
pp. 304-315
Author(s):  
G. Lehmpfuhl
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Crystal Surface ◽  
Diffraction Spot ◽  
Crystal Thickness ◽  
Large Area ◽  
Electron Microscopic ◽  
Additional Information ◽  
Microscopic Investigations

Introduction In electron microscopic investigations of crystalline specimens the direct observation of the electron diffraction pattern gives additional information about the specimen. The quality of this information depends on the quality of the crystals or the crystal area contributing to the diffraction pattern. By selected area diffraction in a conventional electron microscope, specimen areas as small as 1 µ in diameter can be investigated. It is well known that crystal areas of that size which must be thin enough (in the order of 1000 Å) for electron microscopic investigations are normally somewhat distorted by bending, or they are not homogeneous. Furthermore, the crystal surface is not well defined over such a large area. These are facts which cause reduction of information in the diffraction pattern. The intensity of a diffraction spot, for example, depends on the crystal thickness. If the thickness is not uniform over the investigated area, one observes an averaged intensity, so that the intensity distribution in the diffraction pattern cannot be used for an analysis unless additional information is available.

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).

Studies of Oxide Formation on Copper Thin Films by Electron Microscopy

1977 ◽  
Vol 35 ◽  
pp. 316-317
Author(s):  
G. G. Hembree ◽  
M. A. Otooni ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Single Crystal ◽  
Crystal Surface ◽  
Crystal Defects ◽  
Diffraction Reflection ◽  
Reaction Products ◽  
Intermediate Energies ◽  
Crystal Films ◽  
Reflection Electron Microscopy

The formation of oxide structures on single crystal films of metals has been investigated using the REMEDIE system (for Reflection Electron Microscopy and Electron Diffraction at Intermediate Energies) (1). Using this instrument scanning images can be obtained with a 5 to 15keV incident electron beam by collecting either secondary or diffracted electrons from the crystal surface (2). It is particularly suited to studies of the present sort where the surface reactions are strongly related to surface morphology and crystal defects and the growth of reaction products is inhomogeneous and not adequately described in terms of a single parameter. Observation of the samples has also been made by reflection electron diffraction, reflection electron microscopy and replication techniques in a JEM-100B electron microscope.A thin single crystal film of copper, epitaxially grown on NaCl of (100) orientation, was repositioned on a large copper single crystal of (111) orientation.

Field ion microscopy

1988 ◽  
Vol 46 ◽  
pp. 434-435
Author(s):  
Gert Ehrlich
Keyword(s):  
Low Temperature ◽  
Sample Surface ◽  
Low Pressure ◽  
Radius Of Curvature ◽  
Field Ion Microscopy ◽  
Phosphor Screen ◽  
Ion Microscopy ◽  
Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

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