Fig. 3
From: Stacking angle-tunable photoluminescence from interlayer exciton states in twisted bilayer graphene
Interlayer exciton binding energy and PLE spectra. a Exciton model diagram showing emission of the XS state after 2-photon excitation of XA or continuum edge state, XS + Δ. b Spatial PL map of CVD tBLG shows enhanced emission from the 16.3° domain and adjacent spectrally overlapping 15.2° domains after 2-photon excitation at 2 × 1.3 eV. c Extended range 2-photon PLE spectrum (black squares) fits to bimodal Gaussian peaks straddling the 1-photon linear absorption spectrum (green line). The total peak splitting δ + Δ, suggests Eb ≅ 0.5 eV. (Inset) 3D PL map showing ~5× PL resonant enhancement of the θ = 16.3° domain
