Photoluminescence quenching studies have been used as a means to study different surface attributes of semiconductor nanocrystals. Here we compare the quenching characteristics of iodine and iodobenzene on different sizes of nanocrystals. Iodine quenches statically via the external heavy atom effect and charge transfer, whereas iodobenzene quenches dynamically and only by way of the external heavy atom effect. This qualitative study shows that in both cases quenching efficiency increases with decreasing size and that in the case of charge transfer quenching the core excitonic state is more efficiently quenched than the surface emission. (C) 2015 Published by Elsevier B.V.