Shapes of Impurity Absorption Bands in Solids

Keil, Thomas

doi:10.1103/physrev.140.a601

Cited by 285 publications

(121 citation statements)

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“…The manifold intensity fits well with a Poisson distribution (for details see Ref. [15]), characteristic of a radiative transition between two electronic states but coupled to a single phonon mode [43,44]. Therefore, the whole of the PL band is ascribed to a single photoexcited electronic state, the so-called X state, as detailed in Ref.…”

Section: Resultsmentioning

confidence: 82%

Luminescence properties of magnetic polarons in EuTe: Theoretical description and experiments in magnetic fields up to 28 T

et al. 2014

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The recent discovery of a polaron-associated zero phonon line in the band-edge photoluminescence of high optical quality EuTe crystals opens up the prospect of answering long-standing questions about the polaron internal structure, thermal stability, and generation efficiency. Here, a Schrödinger equation for the polaron was formulated and resolved by using both variational and self-consistent methods. The theory is in good agreement with measurements of the zero phonon line as a function of magnetic field and temperature, and it could be applied to other polaronic systems. It is deduced that, in EuTe, at 0 K, a polaron carries a magnetic moment of 610μ B , and its binding energy is 27 meV. However, this binding energy does not carry the usual meaning of thermal stability, because it decreases drastically when the sample is warmed up. For instance, at T = 100 K, the binding energy is already reduced to only 6 meV. The thermal destruction of a polaron is brought about by thermal fluctuations of the spin lattice that suppress the electron's self-energy. Photoluminescence excitation spectra of EuTe demonstrate that the photogeneration of polarons becomes increasingly inefficient when the energy of the pumping photon is increased above the band gap.

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Section: Resultsmentioning

confidence: 82%

Luminescence properties of magnetic polarons in EuTe: Theoretical description and experiments in magnetic fields up to 28 T

et al. 2014

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“…For the case that the electronic ground and excited states have equal vibrational energy ho, Keil 8 has shown that the overlap integrals squared reduce to…”

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Resolving the ambiguity in the relation between Stokes shift and Huang–Rhys parameter

Jong

Seijo

Meijerink

et al. 2015

Phys. Chem. Chem. Phys.

258

235

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Electronic transitions in luminescent molecules or centers in crystals couple to vibrations. This results in broadening of absorption and emission bands, as well as in the occurence of a Stokes shift E Stokes . In principle, one can derive from E Stokes the Huang-Rhys parameter S, which describes the microscopic details of the vibrational coupling and can be related to the equilibrium position offset DQ e between the ground state and excited state. The commonly used textbook relations E Stokes = (2S À 1) ho and E Stokes = 2S ho are only approximately valid. In this paper we investigate how E Stokes is related to S, taking into account the effects of a finite temperature. We show that in different ranges of temperature, different approximate relations between E Stokes and S are appropriate. Moreover, we demonstrate that the difference between the barycenters of absorption and emission bands can be used to determine S in an unambiguous way.The position of the barycenter is, contrary to the Stokes shift, unaffected by temperature.

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“…Em processos que envolvem a absorção por moléculas a integral de superposição das funções de onda vibracionais é obtida considerando o princípio Franck-Condon (LIN, 1971;KEIL, 1965) e pode ser expressa na forma,…”

Section: Análise De Frank-condonunclassified

Propriedades ópticas de filmes finos de MEH-PPV preparados por “spin-coating” em diferentes velocidades de rotação.

et al. 2008

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Shapes of Impurity Absorption Bands in Solids

Cited by 285 publications

References 18 publications

Luminescence properties of magnetic polarons in EuTe: Theoretical description and experiments in magnetic fields up to 28 T

Luminescence properties of magnetic polarons in EuTe: Theoretical description and experiments in magnetic fields up to 28 T

Resolving the ambiguity in the relation between Stokes shift and Huang–Rhys parameter

Propriedades ópticas de filmes finos de MEH-PPV preparados por “spin-coating” em diferentes velocidades de rotação.

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