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Molecular Transport Junctions: Propensity Rules for Inelastic Electron Tunneling Spectra

Alessandro Troisi·Mark A. Ratner
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Abstract

We develop a series of propensity rules for interpreting Inelastic Electron Tunneling (IET) spectra of single-molecule transport junctions. IETS has no selection rules, such as those seen in optical, infrared and Raman spectra, because IETS features arise not from the field-dipole interaction characterizing these other spectroscopies, but from vibronic modification of the electronic levels. Expansion of the Landauer-Imry formula in Taylor series in molecular normal coordinates gives a convenient, accurate perturbation-type formula for calculating both frequency and intensity of the IETS spectrum. Expansion in a Dyson-like form permits derivation of propensity rules, both symmetry-based and pathway-deduced, allowing correlation of structure and coupling geometry with the IETS spectrum. These propensity rules work very well for the calculated spectrum of four typical molecular bridges.

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Alessandro Troisi, Mark A. Ratner. 2006-02-27. Molecular Transport Junctions: Propensity Rules for Inelastic Electron Tunneling Spectra. https://doi.org/10.1021/nl0609394

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