Tip-enhanced raman scattering with a nanoparticle-functionalized probe

We carried out the tip-enhanced Raman scattering (TERS) with a tip that is functionalized with a Aunanoparticle (AuNP, with a diameter of 250 nm). The AuNP tip is fabricated by a direct mechanical pickup of a AuNP from a flat substrate, and the TERS signal from the AuNP tip - organic monolayer - Au thin film (thickness of 10 nm) is recorded. We find that such a AuNP-tip interacting with a thin film routinely yields signal enhancement larger than ̃104, which is sufficient not only for local (with detection area of ̃200 nm2) Raman spectroscopy, but also the nanometric imaging of organic monolayers within a reasonable acquisition time (̃20 minutes/image).