Probing the plasmonic near-field by one- and two-photon excited surface enhanced Raman scattering

• Katrin Kneipp and
• Harald Kneipp

Beilstein J. Nanotechnol. 2013, 4, 834–842, doi:10.3762/bjnano.4.94

• near-field of silver nanoaggregates. The experiments reveal enhancement factors of local fields in the hottest hot spots of the near-field and their dependence on the photon energy. Also, the number of the hottest spots and their approximate geometrical size are found. Near-field amplitudes in the

• . Keywords: near-field; plasmonics; silver nanoaggregates; single molecule; surface-enhanced Raman scattering (SERS); Introduction The resonance frequencies of collective oscillations of the electrons in the conduction band in metal nanostructures, which are called surface plasmons, fall in the optical

• imaging of SERS on silver nanoaggregates has directly confirmed nanoparticle junctions to be responsible for single molecule SERS [11]. Computations show dramatic variations in near-field intensities within a few nanometers. Even sophisticated optical experiments cannot reveal these dramatic spatial