Abstract
Silica-shell coated noble metal nanoparticles have shown a good performance in surface enhanced fluorescence and Raman scattering. However, silica-shell coated single noble nanoparticle cannot effectively enhance the optical signal due to the relative weak near-field enhancement. In this paper, [Au-Ag alloy NP cluster]@SiO2 core-shell nanostructure is employed to achieve the effective electric field enhancement. With the specific structure, simultaneous Raman scattering and fluorescence emission enhancement is obtained, and the enhancement comparison of fluorescence emission with Raman scattering in different type agglomeration of metal NPs is investigated in-situ. With different thickness of SiO2 shell, the optimized Raman and fluorescence enhancement systems are obtained, respectively, and corresponding study of power dependence are investigated in detail. The selectively enhanced Raman and fluorescence can be realized via controlling the shell thickness and laser power. Our work provides a non-polarization dependent [metal NP cluster]@SiO2 system, which may have a promising application in portable chemical and biochemistry detecting.
Highlights
The 1:1 ratio of the Au and Ag is chosen in the following parts, and corresponding elemental distribution is obtained through the energy dispersive X-ray (EDX) elemental mapping
The morphology of the obtained isolated Au-Ag alloy NPs, Au-Ag alloy NP clusters, [isolated Au-Ag alloy NP]@SiO2 and [Au-Ag alloy NP cluster]@SiO2 core-shell structure are characterized with TEM
As the laser power decreases, the intensity of the Raman scattering and fluorescence emission have obvious damping, but the Raman signal can still be clearly observed under the lowest power excitation, which results in the high intensity EM field generated by the alloy cluster
Summary
Nobel metal based nanoparticles (NPs), such as silver or gold NPs, have shown a great potential in plasmon sensor (Homola et al, 1999; Chen and Ming, 2012; Rosman et al, 2013), catalyst (Christopher et al, 2011; Han et al, 2015; Vadai et al, 2018; Zhang et al, 2018), biotherapy (Wang et al, 2014), and signal enhancement (Li et al, 2010; Ando et al, 2011; Wang and Kong, 2015) because of the abundant tunable surface plasmon resonance (SPR) peak in wide-range spectrum. Different agglomeration types of Au-Ag alloy NPs are employed to investigate the enhancement effect of the fluorescence and Raman signal. Three different thickness levels of the SiO2 layer are coated on the alloy NPs and clusters to explore the optimized enhancement system for the fluorescence and Raman signal, respectively.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
