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The implications of spatial coherence in tip-enhanced Raman spectroscopy of two-dimensional systems will be discussed. The prototype material is graphene. Based on massive data with improved resolution based on a plasmon-tuned tip pyramid, we show that in the tip-enhanced strong field regime, interference affects the spectral outcome utilized, for example, to quantify defects. The Raman figure of merit, i.e. the relative intensity of the defect-activated Raman band, depends on the TERS enhancement. Graphene sitting on different substrates is also analyzed. Super-resolution is shown to be due to the field configuration resulting from the coupled tip-sample-substrate system, exhibiting a non-trivial spatial surface distribution. The field distribution and the symmetry selection rules are different for non-gap versus gap mode configurations. This influences the overall enhancement which depends on the Raman mode symmetry and substrate structure.
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