title: Uncovering forbidden optical transitions in PbSe nanocrystals.
abstract: The 1S(h,e)-1P(e,h) exciton transition energy of PbSe nanocrystals was determined via two-photon photoluminescence excitation spectroscopy and was found to be in good agreement with predictions from a tight-binding calculation. The two-photon excitation peak occurs at energies very close to a strong feature in the one-photon absorption spectrum and suggests that it should be assigned as a formally forbidden S-P transition. Leading explanations for the unusual strength of the forbidden transition are discussed.
authors.affiliation: Department of Chemistry, University of Rochester, Rochester, NY, USA.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Peterson
authors.forename: Libai
authors.initials: L
authors.lastname: Huang
authors.forename: Christophe
authors.initials: C
authors.lastname: Delerue
authors.forename: Guy
authors.initials: G
authors.lastname: Allan
authors.forename: Todd D
authors.initials: TD
authors.lastname: Krauss
mesh_terms: D004563:Electrochemistry; D007854:Lead / Q000737:chemistry*; D049449:Luminescence; D053768:Metal Nanoparticles / Q000737:chemistry*; D017785:Photons; D012643:Selenium / Q000737:chemistry*; D013057:Spectrum Analysis
chemical_list: D007854:Lead; D012643:Selenium