Photoluminescence properties of silica-based mesoporous materials similar to those of nanoscale silicon
Institute of Atomic and Molecular Sciences, Academia Sinica,
P.O. Box 23-166, Taipei 106, Taiwan, R.O.C.
2 Institute of Surface Chemistry of the National Academy of Sciences of Ukraine, prospekt Nauki 31, Kiev 252650, Ukraine
3 Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia
4 Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, R.O.C.
Corresponding author: a email@example.com
Published online: 15 September 2001
Photoluminescence (PL) from composites of 7- and 15-nm sized silica nanoparticles (SNs) and mesoporous silicas (MSs) induced by 266- (4.66-) and 532-nm (2.33-eV) laser light has been studied at room temperature. The multiband PL from MSs in the range of 1.0-2.1 eV is evidenced to originate from isolated bulk and surface non-bridging oxygens (NBOs) and from NBOs combined with variously placed 1-nm sized pore wall oxygen vacancies (OVs). The nature and diversity of NBO light-emitters are confirmed by ab initio calculations. The PL from SNs exhibits only a short wavelength part of the bands (1.5-2.1 eV) originated from isolated bulk and surface NBOs. This fact indicates that the highly OV-bearing structures occur only in extremely thin ( nm) silica layers. The similarity of spectroscopic properties of silica-based nanoscale materials to those of surface-oxidized silicon nanocrystals and porous silicon, containing silica-passivating layers of the same width, is discussed.
PACS: 78.55.-m – Photoluminescence / 78.55.Mb – Porous materials / 71.15.Mb – Density functional theory, local density approximation, gradient and other corrections
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001