Propensity rules for inelastic electron tunneling spectroscopy of single-molecule transport junctions

Alessandro Troisi*, Mark A. Ratner

*Corresponding author for this work

Research output: Contribution to journalArticle

59 Scopus citations

Abstract

Using a perturbative approach to simple model systems, we derive useful propensity rules for inelastic electron tunneling spectroscopy (IETS) of molecular wire junctions. We examine the circumstances under which this spectroscopy (that has no rigorous selection rules) obeys well defined propensity rules based on the molecular symmetry and on the topology of the molecule in the junction. Focusing on conjugated molecules of C2h symmetry, semiquantitative arguments suggest that the IETS is dominated by ag vibrations in the high energy region and by out of plane modes (au and bg) in the low energy region. Realistic computations verify that the proposed propensity rules are strictly obeyed by medium to large-sized conjugated molecules but are subject to some exceptions when small molecules are considered. The propensity rules facilitate the use of IETS to help characterize the molecular geometry within the junction.

Original languageEnglish (US)
Article number214709
JournalJournal of Chemical Physics
Volume125
Issue number21
DOIs
StatePublished - Dec 18 2006

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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