Measurement of electronic states of PbS nanocrystal quantum dots using scanning tunneling spectroscopy: The role of parity selection rules in optical absorption

Bogdan Diaconescu, Lazaro A. Padilha, Prashant Nagpal, Brian S. Swartzentruber, Victor I. Klimov

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We study the structure of electronic states in individual PbS nanocrystal quantum dots by scanning tunneling spectroscopy (STS) using one-to-two monolayer nanocrystal films treated with 1, 2-ethanedithiols (EDT). Up to six individual valence and conduction band states are resolved for a range of quantum dot sizes. The measured states' energies are in good agreement with calculations using the k·p four-band envelope function formalism. A comparison of STS and optical absorption spectra indicates that some of the absorption features can only be explained by asymmetric transitions involving the states of different symmetries (e.g., S and P or P and D), which points towards the relaxation of the parity selection rules in these nanostructures. STS measurements also reveal a midgap feature, which is likely similar to one observed in previous charge transport studies of EDT-treated quantum dot films.

Original languageEnglish
Article number127406
JournalPhysical review letters
Issue number12
Publication statusPublished - Mar 22 2013


ASJC Scopus subject areas

  • Physics and Astronomy(all)

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