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Excitonic States (excitonic + states)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

Three-dimensional localization of excitons in the InAs/GaAs wetting layer , magnetospectroscopic study

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 4 2009
A. Babinski
Abstract Magnetospectroscopic studies of individual excitonic states confined in potential fluctuations in the InAs/GaAs wetting layer (WL) are presented. A neutral exciton and a trion emission have been identified. They split in magnetic field in two components of orthogonal circular polarizations. The respective Zeeman splitting changes linearly with magnetic field up to 10 T. A significant scatter of the effective excitonic g *-factor is observed, reflecting the distribution of sizes and compositions of potential fluctuations in the WL. The distribution affects also diamagnetic shift of the excitonic emission. The observed properties of the excitons are consistent with a picture of shallow quantum dots formed in the WL due to In composition fluctuations. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Two-photon photoluminescence and exciton binding energies in single-walled carbon nanotubes

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 10 2006
R. Pomraenke
Abstract We compare experimental one- and two-photon luminescence excitation spectra of single-walled carbon nanotubes at room temperature to ab initio calculations. The experimental spectra reveal a Rydberg-like series of excitonic states. The energy splitting between these states is a clear fingerprint of excitonic correlations in carbon nanotubes. From those spectra, we derive exciton binding energies of 0.3,0.4 eV for nanotubes with diameters between 6.8 Å and 9.0 Å. These energies are in quantitative agreement with our theoretical calculations, which predict the symmetries of the relevant excitonic wave functions and indicate that a low-lying optically dark excitonic state may be responsible for the low luminescence quantum yields in nanotubes. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Indirect absorption edge of TlGaSe2 crystals

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2006
Vytautas Grivickas
Abstract Absorption spectra of high-quality layered TlGaSe2 single crystals were measured in a wide temperature range. Results obtained at low temperatures show that the direct excitonic absorption initiating at EGdir = 2.127 eV is perturbed by several series of step-like features inherent for the indirect type transitions. Spectral modelling of these features revealed that: (i) the ground state of indirect exciton, n = 1, has a large Rydberg energy of about 100 meV, and (ii) the enhanced absorption to excited indirect excitonic states, n = 2, 3, exceeds the classical prediction for scaling factors K1ind/n3. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Linear excitonic absorption under an external electric field in quantum dot molecules

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2007
M. Bedoya
Abstract A study of the excitonic states in artificial molecules set up of two vertically coupled double quantum dots is presented. The electron and hole eigenstates are calculated for the quantum dot molecule. In particular, the coupling effect of the barrier and the consequent tunneling is analyzed following the evolution of the absorption spectra as function of the distance between the two dots. On the other hand, the role of the Coulomb correlation between the confined particles is also studied. We present results of relevant interactions in these systems and discuss how the optical properties of double quantum dots are affected by the interdot coupling, by the geometry of the dots and by an applied electric field. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]