Wang Gang, Sun Wenfang
Department of Chemistry and Molecular Biology, North Dakota State University, Fargo, 58105, USA.
J Phys Chem B. 2006 Oct 26;110(42):20901-5. doi: 10.1021/jp0638843.
The electronic absorption spectra and optical-limiting (OL) properties of gold nanoparticle (AuNP) aggregates induced by KCl and NaCl have been investigated using 4.1-ns laser pulses at 532 nm. Although the individual AuNP colloid shows no optical-limiting effect, the AuNP aggregates exhibit significant optical-limiting characteristics. With an increased concentration of KCl and NaCl, the surface plasmon resonance (SPR) band shifts to a longer wavelength, and the optical-limiting performance is enhanced. Both the electronic absorption and optical limiting are influenced by the particle size. The larger the individual nanoparticle, the further red-shifted the SPR band and the stronger the optical limiting. Optical limiting of aggregates induced by KCl is stronger than that of aggregates induced by NaCl. Mechanistic studies reveal that free-carrier absorption is the dominant contributor to the optical limiting, with negligible contribution from nonlinear scattering.
利用532nm的4.1纳秒激光脉冲，研究了由KCl和NaCl诱导形成的金纳米颗粒（AuNP）聚集体的电子吸收光谱和光限幅（OL）特性。尽管单个AuNP胶体没有光限幅效应，但AuNP聚集体却表现出显著的光限幅特性。随着KCl和NaCl浓度的增加，表面等离子体共振（SPR）带向更长波长移动，光限幅性能增强。电子吸收和光限幅都受粒径影响。单个纳米颗粒越大，SPR带红移越明显，光限幅越强。KCl诱导形成的聚集体的光限幅比NaCl诱导形成的聚集体更强。机理研究表明，自由载流子吸收是光限幅的主要贡献因素，非线性散射的贡献可忽略不计。
