Surface-Enhanced Raman Spectroscopy of Nitrates Using Noble Metal Nanostructures Produced by Laser Deposition in Air

Abstract

An effective approach is proposed for fabricating surface-enhanced Raman spectroscopy (SERS) substrates by applying the method pulsed laser deposition in open air to obtain Au and Ag nanostructures. Laser ablation is performed using nanosecond laser pulses at a wavelength of 1064 nm. At certain experimental parameters, the ablation process results in the deposition of material on the substrate, with poor adhesion to it. The morphology and chemical composition of the deposited structures are studied and discussed in detail. The SERS capability of the structures produced is evaluated by using ammonium nitrate as an analyte. The sensitivity of Ag and Au structures is also investigated using several aqueous solutions of ammonium nitrate with different concentrations. It is demonstrated that Ag structures obtained by the proposed method can detect ammonium nitrate at a concentration 20 times lower compared to the normal Raman analysis. The presented method turned out to be a simple, fast, and inexpensive way to fabricate SERS substrates that are an alternative to advanced multistep technologies.