Templated green synthesis of plasmonic silver nanoparticles in onion epidermal cells suitable for surface-enhanced Raman and hyper-Raman scattering

• Marta Espina Palanco,
• Klaus Bo Mogensen,
• Marina Gühlke,
• Zsuzsanna Heiner,
• Janina Kneipp and
• Katrin Kneipp

Beilstein J. Nanotechnol. 2016, 7, 834–840, doi:10.3762/bjnano.7.75

• nanostructures generated in the extracellular space of onion layers and within the epidermal cell walls can serve as enhancing plasmonic structures for one- and two-photon-excited spectroscopy such as surface enhanced Raman scattering (SERS) and surface enhanced hyper-Raman scattering (SEHRS). Our studies

• nanoparticles; surface-enhanced Raman scattering; surface-enhanced hyper-Raman scattering; Introduction Nanostructures made from metals, such as silver, gold, aluminium or palladium in various sizes and shapes attract growing attention because of their interesting properties and broad applications in many

• to the plasmonic nanostructures are probed by surface-enhanced Raman scattering (SERS) and two-photon-excited analogous surface-enhanced hyper-Raman scattering (SEHRS) [21][22]. While SERS signals scale with the local optical field strengths by 104, SEHRS signals have a scaling factor of 106. This

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

• nearly impossible. However, HRS particularly benefits from optical near-fields. The effective cross section for surface enhanced hyper Raman scattering (SEHRS) can be written as where σHRSads describes a “chemically” enhanced hyper Raman cross section compared to that of a “free” molecule, A(ν) describes

• the enhancement of the near-fields at the excitation and hyper Raman scattered wavelengths, respectively. While one-photon excited SERS depends on the field amplitude enhancement in the near-field to the power of four (see Equation 2), surface enhanced hyper Raman scattering (SEHRS) increases with the