Abstract:
We consider tip-enhanced Raman scattering (TERS) on phonons in two-dimensional materials such as graphene or transition metal dichalcogenides. The main question addressed here is what information about phonons at non-zero wave vectors can be extracted from the dependence of the Raman spectrum on the tip position with respect to the sample. It is shown that for single-phonon non-resonant scattering the measurable quantity is the convolution of the phonon spectral function with respect to wavevector with a certain integral kernel, which is determined by the geometry and dielectric properties of the whole structure. The explicit form of this integral kernel is calculated in the simplest model, where the tip is represented by a point polarizable dipole.
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