Monotonic Tuning of Plasmon Resonance Using Deformable Nanoplasmonic Membrane for Surface-enhanced Raman Scattering

Localized surface plasmon resonance (LSPR) is strongly associated with inelastic scattering of biochemical molecules near metal nanostructures, i.e., surface enhanced Raman scattering (SERS). Systematically exploration of the relationship between surface-enhanced Raman spectroscopy (SERS) and the plasmon resonance wavelength has been an experimental limitation due to the lack of reliable and tunable techniques for controlling the LSPR wavelength. In this work, plasmon resonance was actively tuned by mechanical stretching with 1nm resolution for direct investigating of the relationship between the plasmon resonance and SERS. The functional substrates feature nanoplasmonic metal nanostructures on a stretchable elastomer. The elastomeric membrane is uniformly deformed in all directions, resulting in precise change of inter-particle distance. The inter-particle distance gives dynamic tuning of plasmon resonance. The SERS signal enhancement is directly observed by changing the plasmon resonance. This work enables as a guideline for how to select plasmon resonance of substrates to achieve extreme sensitivity of SERS for targeted molecule.