Photoemission spectroscopy of size selected zinc sulfide nanocrystallites

We report photoemission spectroscopic studies of zinc sulfide nanocrystalli tes in the quantum size regime. The nanocrystallites studied have average s izes of 1.8, 2.5, and 3.5 nm and narrow size distributions as determined fr om UV-visible absorption spectroscopy, as well as x-ray diffraction and hig h-resolution transmission electron microscopy. Analysis of sulfur core leve ls from the nanocrystallites show the presence of the three types of sulfur species corresponding to the core, the surface, and the capping layer of t he nanocrystallites. We show that a quantitative analysis of these differen t sulfur components can be used to estimate the sizes of the nanocrystallit es; thus, the obtained sizes are in good agreement with the sizes determine d independently from small angle x-ray diffraction and high-resolution elec tron microscopy. (C) 2001 American Institute of Physics.