Evidence for the light hole in GaAs/AlGaAs quantum wells from optically-pumped NMR and Hanle curve measurements.

•Light-hole-to-conduction band transition is uncovered by OPNMR and Hanle curves.•Phase inversion of signals indicates spin orientation of conduction electrons.•B0 field dependence of quantum well transitions shows Zeeman splitting of states.•Zero-field value for a GaAs/AlGaAs light-hole state can be extracted.•Spin splitting term for the transition energy yields the excitonic g-factor.