Methods and apparatus for the detection of taggants by surface enhanced raman scattering
One embodiment is a SERS enhancing substrate which includes a porous substrate and a Raman enhancing material associated with a surface of the porous substrate. The Raman enhancing material may be a Raman enhancing metal or other Raman enhancing material. The Raman enhancing material may also be configured to improve binding of a taggant to the substrate. The substrate described above may be included in a sample vessel useful for the flow-through analysis of large sample volumes, or for the rapid analysis of very dilute samples. Other embodiments include methods and systems for detecting taggants with SERS and similar techniques.
1. A method of tagging a substance comprising:
associating a SERS-active taggant with the substance;
modifying the SERS-active taggant to form a SERS-active product having a different chemical composition and a different SERS spectrum than the SERS-active taggant; and
detecting the SERS spectrum of the SERS-active product, wherein the SERS active product has different polarization than the SERS-active taggant and wherein the SERS-active taggant is a phenanthroline derivative, the method further comprising reacting the phenanthroline derivative with a bipyridyl ligand to form the SERS-active product.
2. The method of claim 1 wherein the SERS active product has different spectroscopic adsorption strength than the SERS-active taggant.
3. The method of claim 1 wherein the SERS active product is resonant with the excitation wavelength of a Raman spectrometer used to detecting a SERS spectrum of the SERS-active product.
4. The method of claim 1 wherein the bipyridyl ligand comprises (bpy)2RuCl2.
5. The method of claim 1 wherein the phenanthroline derivative comprises 1,4-diethynyl phenanthroline.
6. The method of claim 1 further comprising detecting the SERS spectrum of the SERS-active product by using a SERS excitation wavelength of 514 nm.
7. The method of claim 1 wherein the substance is a fuel.