Dielectric Screening Model for Lattice Vibrations of Diamond-Structure Crystals

1969 ◽  
Vol 186 (3) ◽  
pp. 871-884 ◽  
Author(s):  
Richard M. Martin
Keyword(s):  
Lattice Vibrations ◽  
Diamond Structure ◽  
Screening Model ◽  
Dielectric Screening

Lattice dynamical effects in the frequency analysis of the infrared and Raman spectra of solid parahydrogen

1970 ◽  
Vol 48 (17) ◽  
pp. 2032-2055 ◽  
Author(s):  
J. Noolandi
Keyword(s):  
Intermolecular Interaction ◽  
Frequency Analysis ◽  
Perturbation Scheme ◽  
Lattice Vibrations ◽  
Coupling Constant ◽  
Phonon Interaction ◽  
Quadrupolar Coupling Constant ◽  
Quadrupolar Coupling ◽  
Dielectric Screening ◽  
Experimental Values

The frequency perturbations of the rotation–vibration levels in solid H2, due to the modulation of the anisotropic and vibrational intermolecular interaction by the lattice vibrations, are calculated. The lattice vibrations are treated in the self-consistent harmonic (SCH) approximation with short-range correlations, and the intermolecular interaction is expanded in terms of the quantum crystal phonon operators. The discrepancy between previous calculations of the effective quadrupolar coupling constant and the experimental values is resolved when the roton–phonon interaction is properly renormalized to take into account the long-range phonon correlations. The energy of the induced dipoles in the quadrupolar field of all the H2 molecules in the crystal (dielectric screening energy) is considered, and in particular the effect of this induction energy on the roton band energies is calculated. The frequencies of the infrared and Raman S0(0) lines are analyzed, taking into account the frequency shifts due to the roton–phonon interaction and the dielectric screening energy, and a value of the effective quadrupolar coupling constant which is consistent with other experimental values is derived. New values of the crystalline field constants ε2C and ε4C are given. The shift and splitting of the S1(0) Raman line is recalculated, taking into account the interaction with the lattice vibrations, and the splitting of the S1(0) + S1(0) doublet in the overtone infrared spectrum is calculated using a different perturbation scheme from the previous calculations. The limitations on the frequency analysis due to the uncertainty in the roton–phonon coupling parameters are discussed.

ELECTROSTATIC ENERGY AND LATTICE VIBRATIONS IN THIN IONIC SLABS

1981 ◽  
Vol 42 (C6) ◽  
pp. C6-341-C6-343
Author(s):  
G. Kanellis ◽  
J. F. Morhange ◽  
M. Balkanski
Keyword(s):  
Electrostatic Energy ◽  
Lattice Vibrations

Application of the EPA hydrocarbon spill screening model to a hydrocarbon contaminated site in Thailand

2002 ◽  
Vol 10 (1) ◽  
pp. 17-24
Author(s):  
Vasin Mahatnirunkul ◽  
Sirintornthep Towprayoon ◽  
Vladimir Bashkin
Keyword(s):  
Contaminated Site ◽  
Screening Model ◽  
Hydrocarbon Spill

Vibration spectra of mixed crystals Sc(PO4, VO4) and Y(PO4, VO4)

1982 ◽  
Vol 47 (4) ◽  
pp. 1176-1183 ◽  
Author(s):  
Alexander Muck ◽  
Olga Smrčková ◽  
Bohumil Hájek
Keyword(s):  
Infrared Spectra ◽  
Group Analysis ◽  
Point Of View ◽  
Mixed Crystals ◽  
Site Symmetry ◽  
Lattice Vibrations ◽  
Vibration Spectra ◽  
Space Group

Infrared spectra of mixed crystals Sc(PO4, VO4) and Y(PO4, VO4) have been studied from the point of view of group analysis. These systems form substitution mixed crystals in tetragonal space group D194h. The anions having proper symmetry Td or D2d in site symmetry D2d exhibit in spectra lowering of the site symmetry to effective C2 as a result of lattice vibrations of the type T(B2).

Infrared Spectroscopy Characterization of Marine Shells

2001 ◽  
Vol 711 ◽  
Author(s):  
Octavio Gomez-Martinez ◽  
Daniel H. Aguilar ◽  
Patricia Quintana ◽  
Juan J. Alvarado-Gil ◽  
Dalila Aldana ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Crassostrea Virginica ◽  
Thermal Treatments ◽  
Vibration Modes ◽  
Lattice Vibrations ◽  
Vibration Frequencies ◽  
Mussel Shells ◽  
Carbonate Lattice

ABSTRACTFourier Transform infrared spectroscopy has been employed to study the shells of two kind of mollusks, American oysters (Crassostrea virginica) and mussels (Ischadium recurvum). It is shown that it is possible to distinguish the different calcium carbonate lattice vibrations in each case, mussel shells present aragonite vibration frequencies, and the oyster shells present those corresponding to calcite. The superposition, shift and broadening of the infrared bands are discussed. Changes in the vibration modes due to successive thermal treatments are also reported.

scholarly journals Dielectric screening in perovskite photovoltaics

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Rui Su ◽  
Zhaojian Xu ◽  
Jiang Wu ◽  
Deying Luo ◽  
Qin Hu ◽  
...  
Keyword(s):  
Open Circuit Voltage ◽  
Low Voltage ◽  
Power Conversion ◽  
Surface Recombination ◽  
Open Circuit ◽  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
Dielectric Screening ◽  
Perovskite Photovoltaic ◽  
Reduced Surface

AbstractThe performance of perovskite photovoltaics is fundamentally impeded by the presence of undesirable defects that contribute to non-radiative losses within the devices. Although mitigating these losses has been extensively reported by numerous passivation strategies, a detailed understanding of loss origins within the devices remains elusive. Here, we demonstrate that the defect capturing probability estimated by the capture cross-section is decreased by varying the dielectric response, producing the dielectric screening effect in the perovskite. The resulting perovskites also show reduced surface recombination and a weaker electron-phonon coupling. All of these boost the power conversion efficiency to 22.3% for an inverted perovskite photovoltaic device with a high open-circuit voltage of 1.25 V and a low voltage deficit of 0.37 V (a bandgap ~1.62 eV). Our results provide not only an in-depth understanding of the carrier capture processes in perovskites, but also a promising pathway for realizing highly efficient devices via dielectric regulation.

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