The surface luminescence of silica nanospheres depending on different excitation wavelengths and accompanied photochemic
- PDF / 857,077 Bytes
- 9 Pages / 547.087 x 737.008 pts Page_size
- 13 Downloads / 137 Views
RESEARCH PAPER
The surface luminescence of silica nanospheres depending on different excitation wavelengths and accompanied photochemical reactions Lei Yang • Dongpo Su • Yajuan She Jiazhang Dong • Aiping Hu
•
Received: 1 June 2013 / Accepted: 5 November 2013 / Published online: 16 November 2013 Ó Springer Science+Business Media Dordrecht 2013
Abstract We report a novel scheme for investigating the emission on the surface of silica depending on different excitation wavelengths and accompanied photochemical reactions. Silica nanospheres with a typical feature of quality fractal are fabricated by drying out the hydrolysates of tetraethylorthosilicate in alcohol-absent aqueous solution. The residual organic groups sustain a comparatively stable surface system, kinetically hindering the relaxation of the defect structures. This surface state provides stable and intermediate energy states to accommodate the excitation electrons. Multiphoton processes accelerate the dissociation energy of the Si–O bond and therefore, greatly decrease the photoreaction threshold of photochemical reactions. Thus, different radiation energy stimulates different photochemical processes and thereby creates different luminescence centers on the surface of silica. It becomes possible to tune the position of the emission band by adjust the excitation conditions. The study is significant not only in control and adjusts the surface defects, but also in colortunable optoelectronic nanodevice. Keywords Silica Nanospheres Photoluminescence Photochemical reaction
L. Yang (&) D. Su Y. She J. Dong A. Hu College of Materials Science and Engineering, Hunan University, Changsha 410082, People’s Republic of China e-mail: [email protected]
Introduction The miniaturization down to nanoscale introduces intrinsic peculiar properties, such as the visible photoluminescence under ultraviolet (UV) excitation (Ma et al. 2012; Pizani et al. 2008; Smedskjaer et al. 2011), potentially promising for the use of silica nanoparticles as medical nanoprobes or photoelectronic devices without the need of doping with extrinsic fluorophores (Banerjee et al. 2011; Bonacchi et al. 2011). The photoluminescence of amorphous nanosilica are expected to benefit from plenty of emission-related structure defects (Lavinia et al. 2011). The surface atoms have a different nearest neighbors from that in interior. Therefore, the surface of silica is expected to exhibit peculiar luminescence properties (Vaccaro et al. 2010). Up to now, numerous experimental and theoretical efforts have been devoted on surface defects in crystalline and glassy SiO2 (Lavinia et al. 2011; Vaccaro et al. 2010; Iwasaka et al. 2012; Kong et al. 2010), and a general concept has been concluded that surface defects are generated from the dehydration reaction involved in the condensation of silanol groups (Lavinia et al. 2011; Kong et al. 2010; Atsuko et al. 2007). As the excitation energy is usually below the dissociation energy of the Si–O bond (about 8.26 eV) (Wuu et al. 2005), the role of the phot
Data Loading...
