Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Single-Molecule Charge Transport Measurements Reveal Technique-Dependant Perturbations

Published

Author(s)

Dwight S. Seferos, A S. Blum, James G. Kushmerick, Guillermo Bazan

Abstract

We compare scanning tunneling microscopy (STM) imaging with single molecule conductive atomic force microscopy (C-AFM) measurements by probing a series of structurally-related thiol-terminated oligo(phenylenevinylene)s (OPVs) designed to have unique charge-transport signatures. When one or two methylene spacers are inserted between the thiol points of attachment and the OPV core, a systematic reduction in the imaged molecular transconductance and the current transmitted through a metal-molecule-metal junction containing the molecule is observed, indicating good agreement between STM and C-AFM measurements. However, a structure where the OPV backbone is interrupted by a [2.2]paracyclophane core has a low molecular transconductance, as determined from STM images, and a high measured single molecule conductance. This apparent disconnect can be understood by comparing the calculated molecular orbital topology of the OPV with one thiol bound to a gold surface (the geometry in the STM experiment) with the topology of the molecule with both thiol termini bound to gold (relevant to C-AFM). In the former case, a single contact splits low-lying molecular orbitals into two discrete fragments, while in the latter case, molecular orbitals that spans the entire molecule are observed. Although the difference in observed conductance between the two different measurements is resolved, the overall set of observations highlight the importance of using combined techniques to better characterize charge-transport properties relevant to molecular electronics.
Citation
Journal of the American Chemical Society

Citation

Seferos, D. , Blum, A. , Kushmerick, J. and Bazan, G. (2006), Single-Molecule Charge Transport Measurements Reveal Technique-Dependant Perturbations, Journal of the American Chemical Society, [online], https://doi.org/10.1021/ja062898j (Accessed August 15, 2022)
Created August 8, 2006, Updated January 4, 2022