The optical field generated by a nanoplasmonic probe is revealed in tip-enhanced Raman spectroscopy – TERS – experiments. The TERS intensity profile of nano-objects smaller than the probe’s apex has a donut-like shape which resembles the magnitude of the field generated by a point-dipole source, being well described by the Dyadic Green’s function. Having prior knowledge on the excitation field generated by the TERS probe, we measured the width of shear solitons caused by lattice reconstruction in low-angle twisted bilayer graphene, a prominent platform for twistronics, and the extend of defect-induced light emission from graphene edges.

Coherence length (L c) of the Raman scattering process in graphene as a function of Fermi energy is obtained with spatially coherent tip-enhanced Raman spectroscopy. L c decreases when the Fermi energy is moved into the neutrality point, consistent with the concept of the Kohn anomaly within a ballistic transport regime. Since the Raman scattering involves electrons and phonons, the observed results can be rationalized either as due to unusually large variation of the longitudinal optical phonon group velocity v g, reaching twice the value for the longitudinal acoustic phonon, or due to changes in the electron energy uncertainty, both properties being important for optical and transport phenomena that might not be observable by any other technique.

Hybrid organic/inorganic Van der Waals heterostructures have emerged recently with enormous potential applications in nanotechnology and industrial areas. In these heterostructures, the interfacial effects can modulate the final properties, creating further possibilities in the design and operation of innovative devices. With this perspective in mind, we report on an experimental investigation of a hybrid organic/inorganic heterostructure of coronene and a few-layers MoS2. We observe a local enhancement of MoS2 optical properties using both far-field and near-field Raman scattering and photoluminescence. Mainly located at the MoS2 edges and defects, the local enhancement is due to the assembling of coronene molecules in MoS2, as confirmed by atomic force microscopy. Quantum semi-empirical and fully atomistic molecular dynamics (MD) simulations were also used to gain further insights into these phenomena. Our results pave the way to engineer molecules in two-dimensional (2D) layered nanomaterials and control and modulate optical phenomena.