We studied the temperature dependence of the absorption coefficient of amorphous SiO2 in the range from 8 to 17.5 eVobtained by Kramers-Kronig dispersion analysis of reflectivity spectra. We demonstrate the main excitonic resonance at 10.4 eV to feature a close Lorentzian shape redshifting with increasing temperature. This provides a strong evidence of excitons being delocalized notwithstanding the structural disorder intrinsic to amorphous SiO2. Excitons turn out to be coupled to an average phonon mode of 83 meV energy.
Messina, F., Vella, E., Cannas, M., Boscaino, R. (2010). Evidence of delocalized excitons in amorphous solids. PHYSICAL REVIEW LETTERS, 105, 116401-1-116401-4 [10.1103/PhysRevLett.105.116401].
Evidence of delocalized excitons in amorphous solids
MESSINA, Fabrizio;VELLA, Eleonora;CANNAS, Marco;BOSCAINO, Roberto
2010-01-01
Abstract
We studied the temperature dependence of the absorption coefficient of amorphous SiO2 in the range from 8 to 17.5 eVobtained by Kramers-Kronig dispersion analysis of reflectivity spectra. We demonstrate the main excitonic resonance at 10.4 eV to feature a close Lorentzian shape redshifting with increasing temperature. This provides a strong evidence of excitons being delocalized notwithstanding the structural disorder intrinsic to amorphous SiO2. Excitons turn out to be coupled to an average phonon mode of 83 meV energy.
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