Detection of nitroexplosives by surface enhanced Raman spectroscopy on colloidal metal nanoparticles

Gold and silver colloids have been synthesized by chemical reduction methods, and they have been used for detecting molecules in solution with high sensitivity and molecular specificity. The present study focuses on metallic nanoparticles of silver and gold colloids with ∼60-80 nm particle size in surface enhanced Raman and surface enhanced resonance Raman scattering (SERS).; Recent experimental data have demonstrated the effect of metal nanostructures coated with hydrophilic copolymers (silver on thin-polymer film coated glass slide). Results indicated a decrease in the intensity of the SERS in TNT and TNT dye which was still detectable by the enhanced presence of the NO 2 out-of-plane bending modes at 820 and 850 cm-1 and the NO2 stretching mode at 1300-1370 cm-1. It was also observed that the polymer film does not interfere with the signal of SERS in the film and some stretching bands of TNT were detected. In conclusion we found that polymers with carboxylic side chains like 2-hydroxyethylmethacrylate (Methacrylic Acid) cause the silver colloid surface layer to replace citrate ions by chemical species of like charge and similarly with aril carboxyl groups in polymer addition. (Abstract shortened by UMI.)...