posted on 2024-02-05, 20:03authored byOliva
M. Primera-Pedrozo, Alexander B. C. Mantilla, Tanya L. Myers, Yi Gu, Patrick Z. El-Khoury
Tip-enhanced Raman (TER) scattering from molecules residing
at
plasmonic junctions can be used to detect, identify, and image single
molecules. This is most evident for flat molecules interrogated under
conditions
of extreme temperatures and pressure. It is also the case for (bio)molecular
systems that feature preferred orientations/conformations under ambient
laboratory conditions. More complex molecules that can adopt multiple
conformations and/or feature different protonation or charge states
give rise to complex TER spectra. We illustrate how the latter can
be controlled in the case of chloramben molecules coated onto plasmonic
silver nanocubes. We show that characteristic molecular Raman spectra
cannot be obtained when tunneling plasmons are operative, i.e., when
the tip is in direct contact with the chemically functionalized plasmonic
nanoparticles. We rationalize these observations and propose an approach
to less invasive and hence more analytical TER spectral imaging.