title: Unraveling internal structures of highly luminescent PbSe nanocrystallites using variable-energy synchrotron radiation photoelectron spectroscopy.
abstract: The internal structure of PbSe nanocrystals was deduced using synchrotron X-ray photoemission spectroscopy for three different sizes of nanocrystals. The photoemission data revealed the layered structure of PbSe nanocrystals with the crystalline PbSe core surrounded by a nonstoichiometric Pb(1-x)Se shell, finally passivated by a capping agent in the outermost layer. A detailed analysis of the experimental data yielded quantitative information on the thickness of three different layers, which is unavailable through any other technique; moreover, the overall sizes of the nanocrystals probed by transmission electron microscopy were in agreement with the corresponding quantity obtained in the present experiment. The present results provide a plausible explanation for the strong variation in the photoluminescence intensity with size observed for these nanocrystals.
authors.affiliation: Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
authors.forename: Sameer
authors.initials: S
authors.lastname: Sapra
authors.forename: J
authors.initials: J
authors.lastname: Nanda
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Pietryga
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Hollingsworth
authors.forename: D D
authors.initials: DD
authors.lastname: Sarma