Dynamic surface enhanced Raman spectroscopy (SERS): extracting SERS from normal Raman scattering.

We have demonstrated two significant benefits of dynamic surface enhanced raman spectroscopy (DSERS) measurements: removal of instrumental and normal Raman interferences in surface enhanced raman spectroscopy (SERS) spectroscopy and site-selective spectroscopy of adsorbate populations on SERS-active particles. Our first example of shelled nanoparticles at very low concentrations confirmed the benefit of DSERS for removal of an overwhelmingly strong solvent spectral interference. The second benefit, site selection, was demonstrated with 4-mercaptopyridine on bare Au nanoparticles to observe a small population of molecules that were spectroscopically unique from the large population of molecules on the particles. The DSERS spectrum originated from excess variance between a small population of adsorbates on the ensemble of nanoparticles.