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

Abstract

Positron annihilation lifetime spectroscopy (PALS) and positron-electron momentum density (PEMD) studies on multilayers of PbSe nanocrystals (NCs), supported by transmission electron microscopy (TEM), 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.

4 Figures, 1 Supplemental file

References in corpus (4)

• Auger mediated quantum sticking of positrons to surfaces: Evidence for single step transition from a scattering state to a surface image potential bound state
• Surfaces of colloidal PbSe nanocrystals probed by thin-film positron annihilation spectroscopy
• Electronic coupling of colloidal CdSe nanocrystals monitored by thin-film positron-electron momentum density methods
• Positron studies of surfaces, structure and electronic properties of nanocrystals

Cited by in corpus (6)

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