Silver nanodendrites for ultralow detection of thiram based on surface-enhanced Raman spectroscopy

Metal nanostructures with highly branched morphologies are attractive due to their fascinating plasmonic properties which are related to their unique morphological features. In this work a simple fabrication methodology is used for fabrication of surface-enhanced Raman spectroscopy (SERS) substrates composed of branched silver nanostructures with dendritic morphology. The high Raman intensity enhancement factor of the order ∼10¹⁰ was achieved which allows the detection of ∼zeptomole thiram molecules by SERS substrates. The appearance of new bands at 344 cm^-1 and 1521 cm^-1 provides an evidence of contribution of chemical enhancement in SERS. The observed spectral changes in SERS spectrum originate from the adsorption of the analyte on the metal surface and provide an insight into molecule-metal interaction in SERS. The extreme sensitivity of SERS substrates is discussed in terms of the distinction between electromagnetic and chemical enhancement mechanisms. Moreover, the highly sensitive SERS substrates were used for simultaneous detection of Rhodamine B and thiram molecules from their mixture with different individual concentrations demonstrating detection capabilities for the identification of pesticides with dye molecules.