Surfaces of colloidal PbSe nanocrystals probed by thin-film positron annihilation spectroscopy

APL Materials. 2013;1(2):022111-022111 DOI 10.1063/1.4818001


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Journal Title: APL Materials

ISSN: 2166-532X (Online)

Publisher: AIP Publishing LLC

LCC Subject Category: Technology: Electrical engineering. Electronics. Nuclear engineering: Materials of engineering and construction. Mechanics of materials | Technology: Chemical technology: Biotechnology | Science: Physics

Country of publisher: United States

Language of fulltext: English

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L. Chai
W. Al-Sawai
Y. Gao
A. J. Houtepen
P. E. Mijnarends
B. Barbiellini
H. Schut
L. C. van Schaarenburg
M. A. van Huis
L. Ravelli
W. Egger
S. Kaprzyk
A. Bansil
S. W. H. Eijt


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Time From Submission to Publication: 10 weeks


Abstract | Full Text

Positron annihilation lifetime spectroscopy and positron-electron momentum density (PEMD) studies on multilayers of PbSe nanocrystals (NCs), supported by transmission electron microscopy, show that positrons are strongly trapped at NC surfaces, where they provide insight into the surface composition and electronic structure of PbSe NCs. Our analysis indicates abundant annihilation of positrons with Se electrons at the NC surfaces and with O electrons of the oleic ligands bound to Pb ad-atoms at the NC surfaces, which demonstrates that positrons can be used as a sensitive probe to investigate the surface physics and chemistry of nanocrystals inside multilayers. Ab initio electronic structure calculations provide detailed insight in the valence and semi-core electron contributions to the positron-electron momentum density of PbSe. Both lifetime and PEMD are found to correlate with changes in the particle morphology characteristic of partial ligand removal.