Fig. 1: Plasmon coupling to the AFM tip.
From: Real-space imaging of acoustic plasmons in large-area graphene grown by chemical vapor deposition
a The AFM tip couples to the AGP inside the layered structure via the evanescent field above graphene. b The exponentially decaying z-component of the AGP electric field Ez penetrates into the free space above graphene by distance De and couples to the AFM tip that acts as a z-oriented electric dipole pz. c Penetration depth of |Ez | as a function of excitation frequency and spacer thickness calculated for graphene EF = −0.5 eV.
