Detection of explosives by surface enhanced Raman scattering using substrate with a monolayer of ordered Au nanoparticles

Abstract Monolayers with different structures arranged by 5 nm Au nanoparticles were grown using a self-assembly method on Si substrates. Raman spectra of ammonium nitrate (NH 4 NO 3 ) and cyclotrimethylenetrinitramine (RDX) explosives adsorbed on bare and Au nanoparticle covered Si substrates were measured. Effects of Au monolayers and their structures on surface enhanced Raman scattering (SERS) of NH 4 NO 3 and RDX were investigated. The monolayer arranged by Au nanoparticles into linear arrays is more sensitive to the explosives than that arranged into hexagonal close-packed structure. The detection limit using the substrate covered by a monolayer of Au nanoparticle linear arrays is about 7.7 ppm for NH 4 NO 3 and 0.19 ppm for RDX. The integrated intensity of the vibration peak increases linearly with an increase in explosive concentration in log–log scales for both NH 4 NO 3 and RDX. The enhancement factor is 7.0 × 10 4 for RDX. Monolayers of Au nanoparticles arranged into linear arrays have potential applications in detecting or identifying explosives at very low levels of concentration.