Speckled SiO2@Au Core–Shell Particles as Surface Enhanced Raman Scattering Probes

Silica particles of ~800 nm size were functionalized using 3-amino propyl triethoxysilane molecules on which gold particles (~20 nm size) were deposited. The resulting particles appeared to form speckled SiO2@Au core–shell particles. The surface roughness, along with hot spots, due to nanogaps between the gold nanoparticles was responsible for the enhancement of the Raman signal of crystal violet molecules by ~3.2 × 107 and by ~1.42 × 108 of single-wall carbon nanotubes. It has also been observed that the electromagnetic excitation near surface plasmon resonance (SPR) of core–shell particles is more effective than off resonance SPR excitation.

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