title: Density of states measured by scanning-tunneling spectroscopy sheds new light on the optical transitions in PbSe nanocrystals.
abstract: The density-of-states function of individual colloidal PbSe nanocrystals varying in diameter between 3 and 7 nm is measured by resonant tunneling spectroscopy. It is in semiquantitative agreement with tight-binding calculations, but the energy separation between electron (hole) levels of S and P symmetry is systematically smaller than predicted by the theory. These results provide an explanation for the second and third excitonic optical transitions, which have been debated for a long time.
authors.affiliation: Debye Institute, University of Utrecht, PO Box 80000, 3508 TA Utrecht, The Netherlands. P.Liljeroth@phys.uu.nl
authors.forename: Peter
authors.initials: P
authors.lastname: Liljeroth
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Zeijlmans van Emmichoven
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Hickey
authors.forename: Horst
authors.initials: H
authors.lastname: Weller
authors.forename: Bruno
authors.initials: B
authors.lastname: Grandidier
authors.forename: Guy
authors.initials: G
authors.lastname: Allan
authors.forename: Daniël
authors.initials: D
authors.lastname: Vanmaekelbergh