Fig. 1: A and B excitonic intensities are increased on the edge of WSe2 thin films suggesting presence of edge polaritons.
From: Flat dispersion at large momentum transfer at the onset of exciton polariton formation
a High-angle annular dark-field (HAADF) image of a representative edge region of thin film WSe2 as analysed. b EEL spectrum showing the electron energy-loss in electron volts (eV) versus intensity in arbitrary units (au) of monolayer (ML) WSe2 showing peaks for the A, B excitons (annotated with A, B) and Rydberg state excitons (annotated with A’, B’) as well as the C exciton transitions (annotated with C1 and C2). c EEL spectrum of the thin film WSe2 showing peaks for A, B excitons (annotated with A, B). d HAADF image of an edge region of the thin film of WSe2 showing regions of increasing thickness (black = vacuum, dark grey = thinnest to light grey = thickest region). e A exciton intensity map acquired from STEM-EELS of the region as shown in(d), generated by integrating the spectral intensity in arbitrary units (au) over the A excitonic energy-loss peak (same spatial scale bar as in (d); colours in map: integrated peak intensity in au, where dark blue regions = lowest intensity, bright yellow regions = highest intensity). f B exciton integrated intensity map from STEM-EELS of the region as shown in (d) (same spatial scale bar as in (d); colours in map: integrated peak intensity in au, where dark blue regions = lowest intensity, bright yellow regions = highest intensity).
