Surface-enhanced Raman spectroscopy (SERS) is a highly sensitive technique for quantifying trace amounts of analyte adsorbed at a roughened metal surface. Many techniques, including electrochemical etching and e-beam lithography, have been used previously to produce roughened metallic surfaces. In this work we demonstrate how novel gold nanostructured films, which are simply fabricated using gold nanoparticles and latex microspheres, can be used as highly sensitive SERS substrates. The gold films are templated by three dimensional colloidal crystals and display long ranged ordered regions. Since the films are porous on two length scales and, therefore, posses a high surface area, we have investigated their SERS activity using sodium cyanide as a model compound. We have integrated these substrates into a flow chamber and demonstrated the quantitative detection of sodium cyanide from 5 to 500 ppb. Our results also reveal that cyanide detection can be significantly enhanced by lowering the pH after cyanide adsorption, likely indicating a conformational change of the bound cyanide. This study illustrates how novel materials formed by simple wet chemistry techniques can be used in practical devices for the detection of chemical agents, and, more generally, illustrates how material design and spectroscopic evaluation can be rapidly integrated.
|Number of pages
|Proceedings of SPIE - The International Society for Optical Engineering
|Published - 2001