High enhancement factor of SERS probe based on silver nano-structures deposited on a silica microsphere by laser-assisted photochemical method

The high enhancement factor (EF) of surface-enhanced Raman (SERS) probes is an important parameter for high-sensitivity Raman scattering measurement applied to environment control. In this article, we present a SERS probe based on silver nano-structures deposited on silica microsphere surfaces made by the laser-assisted photochemical method and reflection converging mirror for a high EF Raman measurement of ultralow organic compound concentration inliquid environments. The laser-assisted photochemical method can synthesize and homogeneously deposit nano-silvers on a silica microsphere, and the reflection converging mirror can collect more Raman signal to the photo-detector and give high Raman enhancement of the SERS probe. The SERS-activity of the probe is verified by the detection of ultralow concentrations of Rhodamine 6 G in aqueous solutions in the range of 10−4-10−10 M. The obtained results show that the proposed SERS probe has an increase of collected Raman intensity up to 32% in comparison to a SERS probe without reflection converging mirror, and an EF of the SERS probe achieved up to 1.8 × 1010. We believe that the novel SERS probe has a large potential for applications in biochemical sensing techniques.