The effect of local environment on photoluminescence: A time-dependent density functional theory study of silanone groups on the surface of silica nanostructures.
J CHEM PHYS
, Article 034705. 10.1063/1.3155083.
The optical absorption spectrum and lowest photoluminescence (PL) signal for silanone terminated silica nanostructures are studied using time-dependent density functional theory calculations on a range of realistic low energy silica nanocluster models. We show that the broad experimental absorption spectrum for silanone centers [V. A. Radtsig and I. M. Senchenya Russ. Chem. Bull. 45, 1849 (1996)] is most likely the result of a synergetic combination of inhomogeneous broadening, thermal broadening and the small energy differences between different excitations. We further demonstrate that upon relaxation of the excited state the excited electron and hole localize on only one silanone center, and that there is a clear and distinct link between the local environment of a silanone center and its absorption and PL spectra. Finally, we provide strong evidence that the silanone center does not have a double bond between the constituent silicon and oxygen atoms but rather can be probably more aptly described as the =Si+-O- charge-transfer species.
|Title:||The effect of local environment on photoluminescence: A time-dependent density functional theory study of silanone groups on the surface of silica nanostructures|
|Keywords:||charge exchange, density functional theory, infrared spectra, nanostructured materials, photoluminescence, silicon compounds, ultraviolet spectra, visible spectra, CORRELATED MOLECULAR CALCULATIONS, 2ND-ORDER PERTURBATION-THEORY, GAUSSIAN-BASIS SETS, POINT-DEFECTS, VISIBLE PHOTOLUMINESCENCE, OPTICAL-ABSORPTION, SIO2, ATOMS, HYDROGENATION, NANOPARTICLES|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Maths and Physical Sciences
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