Analysis of the phenomenological models for long-wavelength polar optical modes in semiconductor layered systems

1992 ◽  
Vol 45 (20) ◽  
pp. 11944-11948 ◽  
Author(s):  
C. Trallero-Giner ◽  
F. García-Moliner ◽  
V. R. Velasco ◽  
M. Cardona
Keyword(s):  
Phenomenological Models ◽  
Layered Systems ◽  
Long Wavelength ◽  
Optical Modes

Long-wavelength lattice vibrations of Ag3In5Se9 and Ag3In5Te9 single crystals — An inversion of LO- and TO-mode frequencies

2016 ◽  
Vol 30 (18) ◽  
pp. 1650229 ◽  
Author(s):  
Nizami Mamed Gasanly
Keyword(s):  
Refractive Index ◽  
Single Crystals ◽  
Longitudinal Optical ◽  
Absorption Index ◽  
Energy Losses ◽  
Optical Parameters ◽  
Lattice Vibrations ◽  
Frequency Range ◽  
Long Wavelength ◽  
Optical Modes

Infrared (IR) reflectivities are registered in the frequency range of 50–2000 cm[Formula: see text] for Ag3In5Se9 and Ag3In5Te9 single crystals grown by Bridgman method. Three infrared-active modes are detected in spectra. The optical parameters, real and imaginary parts of the dielectric function, the function of energy losses, refractive index, absorption index and absorption coefficient were calculated from reflectivity experiments. The frequencies of transverse and longitudinal optical modes (TO and LO modes) and oscillator strength were also determined. The bands detected in infrared spectra were tentatively attributed to various vibration types (valence and valence-deformation). The inversion of LO- and TO-mode frequencies of the sandwiched pair was observed for studied crystals.

scholarly journals Phenomenological model for long-wavelength optical modes in transition metal dichalcogenide monolayer

2021 ◽  
Vol 103 (23) ◽  
Author(s):  
C. Trallero-Giner ◽  
E. Menéndez-Proupin ◽  
E. Suárez Morell ◽  
R. Pérez-Álvarez ◽  
Darío G. Santiago-Pérez
Keyword(s):  
Transition Metal ◽  
Phenomenological Model ◽  
Transition Metal Dichalcogenide ◽  
Long Wavelength ◽  
Optical Modes

Dielectric properties and long-wavelength optical modes of the high-κoxideLaAlO3

2005 ◽  
Vol 71 (13) ◽  
Author(s):  
Pietro Delugas ◽  
Vincenzo Fiorentini ◽  
Alessio Filippetti
Keyword(s):  
Dielectric Properties ◽  
Long Wavelength ◽  
Optical Modes

Long-wavelength polar optical modes in GaAs semiconductor layered structures

1993 ◽  
Vol 5 (31) ◽  
pp. 5389-5400 ◽  
Author(s):  
R Perez-Alvarez ◽  
F Garcia-Moliner ◽  
V R Velasco ◽  
C Trallero-Giner
Keyword(s):  
Layered Structures ◽  
Long Wavelength ◽  
Optical Modes

Activated Prominences; Mechanisms for Activation and Eruption

1979 ◽  
Vol 44 ◽  
pp. 307-313
Author(s):  
D.S. Spicer
Keyword(s):  
Pressure Gradient ◽  
Density Gradient ◽  
Current Density ◽  
Convective Instability ◽  
Tearing Mode ◽  
Magnetic Shear ◽  
Long Wavelength ◽  
Ideal Mhd ◽  
Gradient Change ◽  
Accelerated Particles

A possible relationship between the hot prominence transition sheath, increased internal turbulent and/or helical motion prior to prominence eruption and the prominence eruption (“disparition brusque”) is discussed. The associated darkening of the filament or brightening of the prominence is interpreted as a change in the prominence’s internal pressure gradient which, if of the correct sign, can lead to short wavelength turbulent convection within the prominence. Associated with such a pressure gradient change may be the alteration of the current density gradient within the prominence. Such a change in the current density gradient may also be due to the relative motion of the neighbouring plages thereby increasing the magnetic shear within the prominence, i.e., steepening the current density gradient. Depending on the magnitude of the current density gradient, i.e., magnetic shear, disruption of the prominence can occur by either a long wavelength ideal MHD helical (“kink”) convective instability and/or a long wavelength resistive helical (“kink”) convective instability (tearing mode). The long wavelength ideal MHD helical instability will lead to helical rotation and thus unwinding due to diamagnetic effects and plasma ejections due to convection. The long wavelength resistive helical instability will lead to both unwinding and plasma ejections, but also to accelerated plasma flow, long wavelength magnetic field filamentation, accelerated particles and long wavelength heating internal to the prominence.

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