Photoemission spectroscopy of size selected zinc sulfide nanocrystallites

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