  We study angular momentum radiation from electrically-biased chiral single
molecular junctions using the nonequilibrium Green's function method. Using
single helical chains as examples, we make connections between the ability of a
chiral molecule to emit photons with angular momentum to the geometrical
factors of the molecule. We point out that the mechanism studied here does not
involve the magnetic moment. Rather, it relies on inelastic transitions between
scattering states originated from two electrodes with different chiral
properties and chemical potentials. The required time-reversal symmetry
breaking is provided by nonequilibrium electron transport. Our work sheds light
on the relationship between geometrical and optoelectrical chiral properties at
single molecular limit.
