Mechanism of the enhancement and quenching of ZnO photoluminescence by ZnO-Ag coupling X. D. Zhou, X. H. Xiao, J. X. Xu, G. X. Cai, F. Ren and C. Z. Jiang EPL, 93 5 (2011) 57009 Published online: 14 March 2011 DOI: 10.1209/0295-5075/93/57009