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RESEARCH PRODUCT
Relaxation processes of point defects in vitreous silica from femtosecond to nanoseconds
Wojciech GaweldaAndrea CannizzoMaurizio LeoneA. CallegariF. Van MourikMajed CherguiErwin Portuondo-campasubject
Physics and Astronomy (miscellaneous)Chemistrypoint defectSilicaNanosecondExcited state (localized; relaxation processes of point defects in vitreous silica from femtosecond to nanoseconds); Excited singlet state; Localized electronic state; Point defects; Vibrational relaxation (relaxation processes of point defects in vitreous silica from femtosecond to nanoseconds); Optical absorption (transient; relaxation processes of point defects in vitreous silica from femtosecond to nanoseconds)Crystallographic defectSettore FIS/07 - Fisica Applicata(Beni Culturali Ambientali Biol.e Medicin)ultrafast spectroscopyNuclear magnetic resonanceQuantum dotExcited stateFemtosecondVibrational energy relaxationNeutronrelaxation point defect vitreous silica nanosecondPhysics::Chemical PhysicsAtomic physicsSpectroscopydescription
We studied ultrafast relaxation of localized excited states at Ge-related oxygen deficient centers in silica using femtosecond transient-absorption spectroscopy. The relaxation dynamics exhibits a biexponential decay, which we ascribe to the departure from the Frank-Condon region of the first excited singlet state in 240 fs, followed by cooling in ∼10 ps. At later times, a nonexponential relaxation spanning up to 40 ns occurs, which is fitted with an inhomogeneous distribution of nonradiative relaxation rates, following a chi-square distribution with one degree of freedom. This reveals several analogies with phenomena such as neutron reactions, quantum dot blinking, or intramolecular vibrational redistribution. © 2008 American Institute of Physics.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2008-09-08 | Applied Physics Letters |