Electron spectroscopic studies of nanowires formed by (GaMn)As growth on GaAs(111)B

► Resonant photoemission demonstrated is capable to identify the development of MnAs catalyzed NWs. ► There is a gradual transition from band-like to atomic-like resonance at the Mn2p threshold. ► Dominance of resonance photoemission over the Auger decay channel is ascribed to dilution of Mn. ► The dilution is unexpected as the segregated MnAs/GaAs state is thermodynamically stable.