Surface enhanced Raman spectroscopy (SERS) is a powerful analysis technique which derives information about chemical bonds in trace amounts of analyte molecules. Thereby molecules are adsorbed onto a metal surface or structure: a so-called SERS substrate.
The detected Raman shift is caused by vibrations in the chemical bonds of the analyte. Thus most chemical species can in theory be identified by this technique. For this reason SERS is used as a versatile analytical tool for both chemical and biochemical sensing in liquid and gas phases.
Now, Michael Schmidt and co-workers have presented a novel, simple method to produce flexible free standing nanopillars for SERS. The nanopillars are made from silicon and the resulting SERS substrate exhibit a remarkably large Raman enhancement due to analyte trapping.
The silicon nanopillars are formed via maskless dry etching. Afterwards silver is deposited onto the silicon nanopillars to form SERS-active substrates. One important point is that the nanopillars are flexible. So hot spots can be created with several pillars leaning together. This leaning effect enables a large enhancement of the Raman signal and therefore a much higher sensitivity. Furthermore, they could demonstrate for the first time that the novel substrates can be used for gas sensing. As this fabrication method can be carried out in any silicon processing facility, the production of large areas of SERS substrates at a minimal becomes possible.
The research is published in Advanced Optical Materials, a new section in Advanced Materials (2010 Impact Factor: 10.880) dedicated to breakthrough discoveries and fundamental research in photonics, plasmonics, metamaterials, and more. Advanced Optical Materials will cover all aspects of light-matter interactions. It will include communications, full papers, and reviews. Look for the first edition, out now!