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

Journal Article · Thu Aug 01 00:00:00 EDT 2013 · APL Materials

DOI:https://doi.org/10.1063/1.4818001· OSTI ID:22269584

Chai, L.; Schut, H.; Schaarenburg, L. C. van; Eijt, S. W. H., ^[1]; Al-Sawai, W.; Barbiellini, B.; Bansil, A. ^[2]; Gao, Y. ^[3]; Houtepen, A. J. ^[3]; Mijnarends, P. E. ^[1]; Huis, M. A. van ^[4]; Ravelli, L.; Egger, W. ^[5]; Kaprzyk, S. ^[2]

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1. Department of Radiation, Radionuclides and Reactors, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, NL-2629 JB Delft (Netherlands)
2. Physics Department, Northeastern University, Boston, Massachusetts 02115 (United States)
3. Department of Chemical Engineering, Faculty of Applied Sciences, Delft University of Technology, Julianalaan 136, NL-2628 BL Delft (Netherlands)
4. Kavli Institute of Nanoscience, Faculty of Applied Sciences, Delft University of Technology, Lorentzweg 1, NL-2628 CJ Delft (Netherlands)
5. Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Werner-Heisenberg-Weg 39, D-85579 Neubiberg (Germany)

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.

• OSTI ID: 22269584
• Journal Information: APL Materials, Vol. 1, Issue 2; Other Information: (c) 2013 Author(s); Country of input: International Atomic Energy Agency (IAEA); ISSN 2166-532X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
DENSITY
ELECTRONIC STRUCTURE
ELECTRONS
LEAD SELENIDES
LIGANDS
NANOSTRUCTURES
PARTICLES
POSITRONS
SPECTROSCOPY
SURFACES
THIN FILMS
TRANSMISSION ELECTRON MICROSCOPY