Journal ArticleDOI
Excitons in Alkali Halides
Yositaka Onodera,Yutaka Toyozawa +1 more
TLDR
In this article, a simple treatment in which the spin-orbit and the electron-hole exchange interactions are taken into account indicates that the intensity ratio of the halogen doublet is fairly sensitive to the exchange energy, while the doublet splitting is not very sensitive.Abstract:
Exciton states in alkali halides are analyzed on the basis of the energy band picture. First the excitons at the point \(\varGamma\) are discussed. A simple treatment in which the spin-orbit and the electron-hole exchange interactions are taken into account indicates that the intensity ratio of the halogen doublet is fairly sensitive to the exchange energy, while the doublet splitting is not very sensitive. It is shown that a pure triplet exciton state exists below the first allowed exciton state. Although such a state has not yet been detected, lifetime broadening of the first peak due to the existence of such a hidden state is conceived to make the magnitude of the width of the first peak comparable with that of the second peak. The pronounced structure observed in K and Rb halides in the spectral region just above the step is ascribed to d e exciton formed at the point X . Multiplicities of the observed absorption peaks are explained in terms of this model. Semiquantitative analysis of the triplet stru...read more
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Book ChapterDOI
Statistical Exchange-Correlation in the Self-Consistent Field
John C. Slater,John C. Slater +1 more
TL;DR: The main point of the method of Gaspar, Kohn, and Sham is that they derived the approximate exchange correction from an approximate Hamiltonian for the system by varying the spin-orbitals to minimize the average value of this Hamiltonians for the ground state as discussed by the authors.
Journal ArticleDOI
Bright triplet excitons in caesium lead halide perovskites
Michael Becker,Michael Becker,Roman Vaxenburg,Georgian Nedelcu,Georgian Nedelcu,Peter C. Sercel,Andrew Shabaev,Michael J. Mehl,John G. Michopoulos,Samuel G. Lambrakos,Noam Bernstein,John L. Lyons,Thilo Stöferle,Rainer F. Mahrt,Maksym V. Kovalenko,Maksym V. Kovalenko,David J. Norris,Gabriele Rainò,Gabriele Rainò,Alexander L. Efros +19 more
TL;DR: In this article, it was shown that the lowest exciton in caesium lead halide perovskites (CsPbX_3, with X = Cl, Br or I) involves a highly emissive triplet state.
Journal ArticleDOI
Branching ratio in x-ray absorption-spectroscopy
B. T. Thole,G. van der Laan +1 more
TL;DR: In this article, the origin of nonstatistical branching ratios in spin-orbit-split x-ray absorption spectra is explained and the results of these atomic calculations in general rules, which are also applicable to solids.
Journal ArticleDOI
Application of the Green's functions method to the study of the optical properties of semiconductors
TL;DR: In this paper, the generalized single-particle Green's function is considered and the Bethe-Salpeter equation for the two-particles Green's functions is defined.
Journal ArticleDOI
Evidence of Effective Potential Barriers in the X‐Ray Absorption Spectra of Molecules
TL;DR: In this paper, the authors interpret the enhanced lines and frequent failure to detect Rydberg structure in the x-ray absorption spectra of molecules in terms of ''inner-well'' and ''outerwell'' states which result from an effective potential barrier located near the electronegative atoms in the molecule.
References
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Journal ArticleDOI
Theory of Line-Shapes of the Exciton Absorption Bands
TL;DR: In this article, a general theory of line-shapes of the exciton absorption bands is developed with the help of generating function, and the half-value width H is given by the level broadening of the optically produced K=O ex· citon due to lattice scattering, so that it is proportional to T except at low.temperatures.
Journal ArticleDOI
Ultraviolet Absorption of Alkali Halides
Journal ArticleDOI
Further Contribution to the Theory of the Line-Shape of the Exciton Absorption Band
TL;DR: In this paper, the authors investigated the line-shape of the exciton absorption band in the limit of weak exciton-phonon coupling, with the use of damping theory.
Journal ArticleDOI
Ultraviolet Absorption of Insulators. III. fcc Alkali Halides
TL;DR: In this article, the optical spectra of the alkali halides are divided into interband scattering and exciton structure, and it is conjectured that the extra excitons are metastable because of self-trapping.
Journal ArticleDOI
Exciton States in Ionic Crystals
Robert S. Knox,Nicolas Inchauspé +1 more
TL;DR: In this article, a theory of the "halogen atom doublet" appearing in the experimental absorption spectra of certain alkali halide crystals is given and used in a preliminary interpretation of the electronic structure of low-lying exciton states in these solids.