We investigated the optical properties of excitons in quasi-one-dimensional semiconductor quantum structures by photoluminescence and photoluminescence excitation: High-quality GaAs/AlxGa1-xAs heterostructures were grown using low-pressure organometallic chemical vapour deposition (OMCVD) on non-planar substrates. The experimentally observed subband separations are in good agreement with a theoretical calculation of the quantum-confined eigenstates, which includes the mapping of the crescent-shaped wire obtained on TEM micrographs. Additionally, a temperature dependence study of excitonic spectra reveals the dominant role of potential and size fluctuations in localizing the excitons.