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Optic deformations

Earlier than all of this Holstein (10) described his optic polaron, in which the deformation of the ID chain is an optic deformation. His was the first polaron solution which was a Solitary Wave or Soliton. In such a deformation there is no change in lattice density in the polaron there is only a rearrangement of atoms without a change of density. In the case of the optic polaron there is no analytical solution for the moving polaron. However it is clear that on increase of the optic polaron energy due to motion there is no perturbation as the velocity goes through the sound velocity. In the pure optic polaron the sound velocity is not in the model at the outset. It is in the motion of the polaron at velocities up to the sound velocity that the profound difference between the acoustic and optic polarons occurs the difference in properties of the polarons at rest is leas Important. [Pg.209]

Carreri et al (13) found infra red absorptions in polypeptides and their model crystal acetanilide which they suggested might be the Davydov Soliton. However it is more likely that they are due to the remaining member of the quartet of Table 1, namely the imide vibration bound in a range of optic deformation (14). [Pg.209]

In this paper, we present the lateral size dependence of Huang-Rhys factors for the QW heterostructures with the localized quasi-2D excitonic states. The Huang-Rhys factor is a quantity representing the coupling strength of a localized particle with phonons [4]. All exciton-phonon interaction mechanisms are analyzed. They are the polar optic (Froehlich) interaction, the optic deformation potential, the acoustic deformation potential, and the acoustic piezoelectric interaction. We would... [Pg.302]

We calculated the size dependence of the zero-temperature Huang-Rhys factors (4) using parameters of GaAs [7]. Fig. 1(a) shows the optic Huang-Rhys factors of 2D-excitons (flat dot) as a function of the QD lateral size. The Froehlich interaction is seen to dominate over the optic deformation potential interaction (caused by the heavy hole interaction in a p-like valence band). The total optic Huang-Rhys factor gradually increases with the decreasing QD lateral size. [Pg.304]

The polaron moving at supersonic velocities has a distinct difference compared to the static polaron, i.e., the absence of an acoustic compression of the lattice around the localized charge. However, the deformation described by the optical order parameter is more or less the same for the two types of defects. Our simulations show clearly that these optical deformations can move along the polymer chain at supersonic velocities. [Pg.76]

Matsui T, Ozaki M, Yoshino K (2004) Tunable photonic defect modes in a cholesteric liquid crystal induced by optical deformation of helix. Phys Rev E 69 061715 Yoshida H, Lee CH, Fujii A, Ozaki M (2007) Tunable chiral photonic defect modes in locally polymerized cholesteric liquid crystals. Mol Cryst Liq Cryst 477 255... [Pg.112]

In ID the lattice deforms around the electron and loced.ises the electron to form a polaron. The ii portant deformation is acoustic, in udiich the density of the lattice changes optic deformations occur also but are not important in the polaron motion. The mathematical description of the polaron is like that of solitary waves. The Solitary wave Acoustic Polaron (SWAP) has a very large effective mass its kinetic velocity is small. Horeover it cannot move at a velocity greater than S as its kinetic velocity approaches S the acoustic deformation increases and the SNAP mass increases. In addition back scattering is very rare. So the SWAP kinetic and drift velocities are equal. [Pg.157]

Often industry requires fast techniques to measure movements, deformations, etc. The optics methods, between them those based in speckle K gives quick solutions to this problems. [Pg.656]

Ash Fusibility. A molded cone of ash is heated in a mildly reducing atmosphere and observed using an optical pyrometer during heating. The initial deformation temperature is reached when the cone tip becomes rounded the softening temperature is evidenced when the height of the cone is equal to twice its width the hemispherical temperature occurs when the cone becomes a hemispherical lump and the fluid temperature is reached when no lump remains (D1857) (18). [Pg.233]

In a dynamic event, one obtains only one X-ray per X-ray head, as opposed to a number of optical photographs taken through a given optical lens. Often several X-ray heads are used to show the evolution of the deformation, but each X-ray views the event from a different angle and it is not uncommon to view the event orthogonally. This can be used to advantage to determine the location of certain features through parallax. For a review on this technique, see Isbell (1987). [Pg.68]

Thin sheets of mica or polymer films, which are coated with silver on the back side, are adhered to two cylindrical quartz lenses using an adhesive. It may be noted that it is necessary to use an adhesive that deforms elastically. One of the lenses, with a polymer film adhered on it, is mounted on a weak cantilever spring, and the other is mounted on a rigid support. The axes of these lenses are aligned perpendicular to each other, and the geometry of two orthogonally crossed cylinders corresponds to a sphere on a flat surface. The back-silvered tbin films form an optical interferometer which makes it possible... [Pg.95]

Israelachvili and coworkers [64,69], Tirrell and coworkers [61-63,70], and other researchers employed the SFA to measure molecular level adhesion and deformation of self-assembled monolayers and polymers. The pull-off force (FJ, and the contact radius (a versus P) are measured. The contact radius, the local radius of curvature, and the distance between the surfaces are measured using the optical interferometer in the SFA. The primary advantage of using the SFA is its ability to study the interfacial adhesion between thin films of relatively high... [Pg.97]

Perhaps the most significant complication in the interpretation of nanoscale adhesion and mechanical properties measurements is the fact that the contact sizes are below the optical limit ( 1 t,im). Macroscopic adhesion studies and mechanical property measurements often rely on optical observations of the contact, and many of the contact mechanics models are formulated around direct measurement of the contact area or radius as a function of experimentally controlled parameters, such as load or displacement. In studies of colloids, scanning electron microscopy (SEM) has been used to view particle/surface contact sizes from the side to measure contact radius [3]. However, such a configuration is not easily employed in AFM and nanoindentation studies, and undesirable surface interactions from charging or contamination may arise. For adhesion studies (e.g. Johnson-Kendall-Roberts (JKR) [4] and probe-tack tests [5,6]), the probe/sample contact area is monitored as a function of load or displacement. This allows evaluation of load/area or even stress/strain response [7] as well as comparison to and development of contact mechanics theories. Area measurements are also important in traditional indentation experiments, where hardness is determined by measuring the residual contact area of the deformation optically [8J. For micro- and nanoscale studies, the dimensions of both the contact and residual deformation (if any) are below the optical limit. [Pg.194]

Step 3. The set of fracture properties G(t) are related to the interfaee structure H(t) through suitable deformation mechanisms deduced from the micromechanics of fracture. This is the most difficult part of the problem but the analysis of the fracture process in situ can lead to valuable information on the microscopic deformation mechanisms. SEM, optical and XPS analysis of the fractured interface usually determine the mode of fracture (cohesive, adhesive or mixed) and details of the fracture micromechanics. However, considerable modeling may be required with entanglement and chain fracture mechanisms to realize useful solutions since most of the important events occur within the deformation zone before new fracture surfaces are created. We then obtain a solution to the problem. [Pg.355]

The sample eapsule is plaeed in a tight-fitting 4340 steel fixture that serves to support the eopper eapsule. Pressure from the detonation of the explosive is transmitted to the eopper eapsule through a mild steel driver plate. This plate is also lapped optically flat on both surfaces. The mild steel acts to shape the pressure pulse due to the 13 GPa structural phase transition. With proper choice of the diameter of the driver plate and beveled interior opening of the steel fixture, shock deformation of the driver plate acts to seal the capsule within the fixture. [Pg.152]

The various studies of shock-modified powders provide clear indications of the principal characteristics of shock modification. The picture is one in which the powders have been extensively plastically deformed and defect levels are extraordinarily large. The extreme nature of the plastic deformation in these brittle materials is clearly evident in the optical microscopy of spherical alumina [85B01]. In these defect states their solid state reactivities would be expected to achieve values as large as possible in their particular morphologies greatly enhanced solid state reactivity is to be expected. [Pg.171]

Fig.l. Optical microstructure of alloy after hot deformation a) by 25 %, magnification lOOx, b) by 50%, magnification 60x... [Pg.398]

This stress-strain behavior is consistent with the optic metallographic data which evidenced partial redistribution of hydrogen over the powder particles when the compacting temperature was increased to 400°C and uniform hydrogen distribution on additional annealing or during plastic deformation at T > 500°C. [Pg.433]


See other pages where Optic deformations is mentioned: [Pg.247]    [Pg.3]    [Pg.209]    [Pg.306]    [Pg.310]    [Pg.195]    [Pg.304]    [Pg.49]    [Pg.136]    [Pg.77]    [Pg.539]    [Pg.225]    [Pg.565]    [Pg.211]    [Pg.90]    [Pg.247]    [Pg.3]    [Pg.209]    [Pg.306]    [Pg.310]    [Pg.195]    [Pg.304]    [Pg.49]    [Pg.136]    [Pg.77]    [Pg.539]    [Pg.225]    [Pg.565]    [Pg.211]    [Pg.90]    [Pg.41]    [Pg.253]    [Pg.421]    [Pg.434]    [Pg.111]    [Pg.164]    [Pg.106]    [Pg.6]    [Pg.186]    [Pg.269]    [Pg.314]    [Pg.1268]    [Pg.182]    [Pg.216]    [Pg.231]   
See also in sourсe #XX -- [ Pg.157 ]




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