Bound states in continuum in graphene interfaces

We present experimental evidence of discrete bound states coexisting in the continuum (BIC) in certain graphene interface systems. The interaction of discrete states and the continuum is enabled by interface quantum confinement, and is a direct result of resonant interlayer multiple scattering. We used elastic electron back-scattering, in the very low energy range, to characterize these interlayer resonant states in graphene, using a low energy electron microscope (LEEM). We used Raman spectroscopy to further probe the inelastic light-matter interaction. We discovered a unique type of Fano-resonance around the D mode and G mode of the graphene lattice vibrations. The anomalous Fano-resonance is also a direct result of the quantum confinement and interplay between discrete phonon states and excitonic electronic continuum.