Protocol and reference material for measuring the nanoantenna enhancement factor in Tip-enhanced Raman Spectroscopy
There is up to date no agreement on what is the enhancement factor (fe) in tip-enhanced Raman Spectroscopy (TERS). The complexity resides both on the lack of a proper theoretical definition and of a reliable experimental procedure for measuring it. Here we propose a protocol and a reference material to characterize the intrinsic fe value of a TERS nanoantenna. The protocol is based on the theoretical description of the tip-sample approach curve, which should be performed in a reference material made of a well-defined near-field Raman scattering properties together with other specificities that allows measuring all the parameters necessary to fully optimize and characterize the measuring system.