We have measured surface-enhanced resonance Raman scattering (SERRS) spectra of rhodamine 6G (R6G) at concentrations as low as 8 × 10<sup>-16</sup> M in colloidal silver solution activated by NaCl ions. The spectra were measured with a fiber-optic probe using the 514.5-nm argon-ion laser line as excitation source and a charge-coupled-device (CCD) detection system. The correlation of SERRS photo counts and R6G concentration was found to be linear between 8 × 10<sup>-11</sup> and 8 × 10<sup>-14</sup> M concentrations within our experimental accuracy. Experiments conducted with small scattering volumes show that fewer than 100 R6G molecules are sufficient to give rise to a SERRS spectrum with reasonable signal-to-noise ratio. These results demonstrate that in certain cases SERRS can achieve detection limits comparable to those for fluorescence spectroscopy, and at the same time provides higher structural specificity than fluorescence. The possibilities of using SERRS for single molecule detection are discussed.
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Contact your librarian or system administrator
Login to access Optica Member Subscription