Uncovering forbidden optical transitions in PbSe nanocrystals.

Peterson, Jeffrey J; Huang, Libai; Delerue, Christophe; Allan, Guy; Krauss, Todd D · Nano Lett · 2007

basic_science · Level V

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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.

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