A surface-enhanced Raman scattering method and apparatus to sequence polymeric biomolecules such as DNA, RNA, or proteins is introduced. The method uses metallic nanostructures such as, for example, spherical or cylindrical Au or Ag nanoparticles having characteristic lengths of 10-100 nm which when illuminated with light of the appropriate wavelength produce resonant oscillations of the conduction electrons (plasmon resonance). Electric field enhancements of 30-1000 near the particle surface resulting from such oscillations increase Raman scattering cross-sections by about 10.sup.6-10.sup.15 due to the E.sup.4 dependence of the Raman scattering, wherein the largest enhancements occur in the gap/junction between novel closely spaced structures as disclosed herein.
 The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory.