Luminescence from nearly isolated surface defects in silica nanoparticles.
J Phys Condens Matter
; 27(36): 365301, 2015 Sep 16.
Article
in En
| MEDLINE
| ID: mdl-26302715
ABSTRACT
A structured emission/excitation pattern, proper of isolated defects, arises in a vacuum from silica nanoparticles. The luminescence, centered around 3.0-3.5 eV, is characterised by a vibronic progression due to the phonon coupling with two localised modes of frequency â¼1370 cm(-1) and â¼360 cm(-1), and decays in about 300 ns at 10 K. On increasing the temperature, the intensity and the lifetime decrease due to the activation of a non-radiative rate from the excited state. Concurrently, the temperature dependence of the lineshape evidences the low coupling with non-localised modes of the matrix (Huang-Rhys factor S ~ 0.2) and the poor influence of the inhomogeneous broadening. These findings outline an uncommon behaviour in the field of the optical properties of defects in amorphous solids, evidencing that the silica surface can allocate luminescent defects almost disentangled from the basal network.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Language:
En
Journal:
J Phys Condens Matter
Journal subject:
BIOFISICA
Year:
2015
Document type:
Article
Affiliation country:
Italia