  The optical properties of particularly the tungsten-based transition-metal
dichalcogenides are strongly influenced by the presence of dark excitons.
Recently, theoretical predictions as well as indirect experimental insights
have shown that two different dark excitons exist within the light cone. While
one is completely dark, the other one is only dipole forbidden out-of-plane,
hence referred to as grey exciton. Here, we present angle-resolved
spectroscopic data of a high-quality hexagonal-BN-encapsulated WSe2 monolayer
with which we directly obtain the radiation pattern of this grey exciton that
deviates from that of the bright exciton and other exciton complexes obtained
at cryogenic temperatures.
