Photoluminescence in the fractional quantum Hall regime

We study the photoluminescence spectrum of a low density (ν<1) two-dimensional electron gas at high magnetic fields and low temperatures. We find that the spectrum in the fractional quantum Hall regime can be understood in terms of singlet and triplet charged-excitons. We identify the dark triplet charged-exciton and show that it is visible in the spectrum at View the MathML source. We find that its binding energy scales like e2/l, where l is the magnetic length, and it crosses the singlet slightly above View the MathML source.