Pesticide detection optimization of plasmonics gold nanoparticles/silicon nano-columns structures by controlling the coupling lasers power density

Fixed laser pulse duty cycle at 20% using short laser wavelength (405 nm) at different values of laser power density (300–600 mW/cm 2 ) were used to form Si nano-columns as based SERS layer. The idea was to synthesize SERS devices with excellent reproducibility and high enhancement factor to detect ultra-low residence of chlorpyrifos pesticide. The results indicated that the morphological aspects of silicon nano-columns layer and; hence, the performance of SERS devices could be well-regulated through the adjustment of laser power density. The SERS detection of ultra-low chlorpyrifos concentrations displayed an excellent reproducibility with less than 5% error. The highest chlorpyrifos enhancement factor (EF = 1.1 × 10 6 ) and minimum detection limit (LOD = 22 × 10 −8 M) were obtained from high altitude Si nano-columns; partly populated with three dimensions AuNPs layer, and the use of 500mW/cm 2 laser power density.