We have studied the photoinduced transformation of small rings (three membered) in amorphous silica by Car-Parrinello simulations. The process of ring opening leading to the formation of a couple of paramagnetic centers, namely an E' and a nonbridging-oxygen hole center (NBOHC), has been proposed experimentally to occur in silica exposed to F-2 laser irradiation (at 7.9 eV). By using a scheme for the simulation of rare events in ab initio molecular dynamics [M. Iannuzzi, A. Laio, and M. Parrinello, Phys. Rev. Lett. 90, 238303 (2003)], we have identified a transformation path for the opening of a three-membered ring induced by a self-trapped triplet exciton, the migration of NBOHC and formation of a couple of stable E' and NBOHC paramagnetic defects.
Donadio, D., Bernasconi, M. (2005). Ab initio simulation of photoinduced transformation of small rings in amorphous silica. PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS, 71(7) [10.1103/PhysRevB.71.073307].
Ab initio simulation of photoinduced transformation of small rings in amorphous silica
BERNASCONI, MARCO
2005
Abstract
We have studied the photoinduced transformation of small rings (three membered) in amorphous silica by Car-Parrinello simulations. The process of ring opening leading to the formation of a couple of paramagnetic centers, namely an E' and a nonbridging-oxygen hole center (NBOHC), has been proposed experimentally to occur in silica exposed to F-2 laser irradiation (at 7.9 eV). By using a scheme for the simulation of rare events in ab initio molecular dynamics [M. Iannuzzi, A. Laio, and M. Parrinello, Phys. Rev. Lett. 90, 238303 (2003)], we have identified a transformation path for the opening of a three-membered ring induced by a self-trapped triplet exciton, the migration of NBOHC and formation of a couple of stable E' and NBOHC paramagnetic defects.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.