Scattering wave vector dependence of Raman intensity of the v1 internal mode in KH2PO4

1985 ◽  
Vol 54 (11) ◽  
pp. 979-980 ◽  
Author(s):  
Y. Tominaga ◽  
M. Tokunaga ◽  
I. Tatsuzaki
Keyword(s):  
Wave Vector ◽  
Raman Intensity ◽  
Internal Mode ◽  
Scattering Wave

COMPUTATION OF THE NORMAL AND ANOMALOUS TERMS IN THE LOWEST ORDER ANHARMONIC CONTRIBUTIONS TO THE DEBYE-WALLER FACTOR FOR SODIUM METAL

1994 ◽  
Vol 05 (02) ◽  
pp. 303-309
Author(s):  
Sajalendu Dey
Keyword(s):  
Wave Vector ◽  
Waller Factor ◽  
Sodium Metal ◽  
Debye Waller Factor ◽  
Scattering Wave ◽  
Anharmonic Crystals

It has been shown by Maradudin and Flinn1 (1963) that, in weak anharmonic crystals, the lowest order anharmonic contributions to the Debye-Waller factor are of 0(λ2), where λ is the Van Hove2 (1961) ordering parameter. There are four such terms, two of them are of [Formula: see text] (where [Formula: see text] is the scattering wave-vector) and are known as the normal terms. Other two terms are of [Formula: see text] and are known as the anomalous terms. These four terms are of significant complexity. In this present work, a computation of these four terms will be reported for sodium metal and the results will be compared with experimentally determined values.

Effects of Higher-Order Laue Zone reflections on structure images

1993 ◽  
Vol 51 ◽  
pp. 450-451
Author(s):  
H. S. Kim ◽  
S. S. Sheinin
Keyword(s):  
Wave Vector ◽  
Theoretical Calculations ◽  
Reciprocal Lattice ◽  
Image Plane ◽  
Bloch Wave ◽  
Dynamical Theory ◽  
Higher Order ◽  
Lattice Image ◽  
Lattice Vector ◽  
Image Position

The importance of image simulation in interpreting experimental lattice images is well established. Normally, in carrying out the required theoretical calculations, only zero order Laue zone reflections are taken into account. In this paper we assess the conditions for which this procedure is valid and indicate circumstances in which higher order Laue zone reflections may be important. Our work is based on an analysis of the requirements for obtaining structure images i.e. images directly related to the projected potential. In the considerations to follow, the Bloch wave formulation of the dynamical theory has been used.The intensity in a lattice image can be obtained from the total wave function at the image plane is given by: where ϕg(z) is the diffracted beam amplitide given by In these equations,the z direction is perpendicular to the entrance surface, g is a reciprocal lattice vector, the Cg(i) are Fourier coefficients in the expression for a Bloch wave, b(i), X(i) is the Bloch wave excitation coefficient, ϒ(i)=k(i)-K, k(i) is a Bloch wave vector, K is the electron wave vector after correction for the mean inner potential of the crystal, T(q) and D(q) are the transfer function and damping function respectively, q is a scattering vector and the summation is over i=l,N where N is the number of beams taken into account.

Wave-Vector-Varying Pancharatnam-Berry Phase Photonic Spin Hall Effect

2021 ◽  
Vol 126 (8) ◽  
Author(s):  
Wenguo Zhu ◽  
Huadan Zheng ◽  
Yongchun Zhong ◽  
Jianhui Yu ◽  
Zhe Chen
Keyword(s):  
Hall Effect ◽  
Wave Vector ◽  
Berry Phase ◽  
Spin Hall Effect

scholarly journals Mechanisms of electron-phonon coupling unraveled in momentum and time: The case of soft phonons in TiSe2

2021 ◽  
Vol 7 (20) ◽  
pp. eabf2810
Author(s):  
Martin R. Otto ◽  
Jan-Hendrik Pöhls ◽  
Laurent P. René de Cotret ◽  
Mark J. Stern ◽  
Mark Sutton ◽  
...  
Keyword(s):  
Wave Vector ◽  
Density Wave ◽  
Phonon Coupling ◽  
Many Body ◽  
Soft Zone ◽  
Electron Phonon Coupling ◽  
Underlying Mechanisms ◽  
The Many ◽  
Coupling Phenomena ◽  
Electron Pocket

The complex coupling between charge carriers and phonons is responsible for diverse phenomena in condensed matter. We apply ultrafast electron diffuse scattering to unravel electron-phonon coupling phenomena in 1T-TiSe2 in both momentum and time. We are able to distinguish effects due to the real part of the many-body bare electronic susceptibility, R[χ0(q)], from those due to the electron-phonon coupling vertex, gq, by following the response of semimetallic (normal-phase) 1T-TiSe2 to the selective photo-doping of carriers into the electron pocket at the Fermi level. Quasi-impulsive and wave vector–specific renormalization of soft zone-boundary phonon frequencies (stiffening) is observed, followed by wave vector–independent electron-phonon equilibration. These results unravel the underlying mechanisms driving the phonon softening that is associated with the charge density wave transition at lower temperatures.

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