Z(1,2) exciton resonant luminescence in large size CuCl nanocrystallites

Near-resonant conditions upon the highly degenerated (2S) Z(1,2)-exciton ba nd are used to take advantage of a disorder-induced relaxation of the k-sel ection rule in order to investigate the unreported direct activation of the (1S) Z(1,2) exciton luminescence in large-size CuCl nanocrystallites. Extr emely rich spectra display simultaneously the (1S) Z(3) and (1S) Z(1,2) lum inescences. Moreover the unusual antistokes shift between the maxima of the Z(1,2) excitonic absorption and emission bands is attributed to an apparen t increase in the spatial confinement due to resonance-related density effe cts. This point supports the key idea of a resonance-based activation of th e Z(1,2) exciton in the photoluminescence spectra. (C) 2000 Elsevier Scienc e S.A. All rights reserved.