  Magneto-luminescence studies in electron bilayers reveal the hallmarks of the
even-denominator and other quantum Hall states in the intensities and energies
of the inter-band optical recombination lines. In the presence of a small
tunneling gap between the layers the magneto-optical emission from the lowest
anti-symmetric subband, not populated in a single-electron picture, displays
maxima at filling factors 1 and 2/3. These findings uncover a loss of
pseudospin polarization, where the pseudospin describes the layer index degree
of freedom, that is linked to an anomalous population of the anti-symmetric
level due to excitonic correlations. The results demonstrate a new realm to
probe the impact of inter-layer Coulomb interaction in quantum Hall bilayers.
