Probing charge states in molecular junctions using Raman spectroscopy

Fatemeh Mirjani*, Joseph M. Thijssen, Mark A. Ratner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


We examine the Raman spectra of a series of molecules in different charge states and suggest ways of controlling these charge states in charge transport experiments. Our study uses density functional theory (DFT)-based quantum chemical methods. The molecules we study are benzene derivatives, which accommodate transport either through the HOMO or the LUMO (where the HOMO and the LUMO denote the highest occupied molecular orbital and lowest unoccupied molecular orbital, respectively). We have investigated whether observable differences in the Raman spectra will occur upon electron addition or removal. We find substantial frequency shifts upon electron removal or addition. These shifts tend to be uniformly downward in the case of LUMO transport, whereas, for HOMO transport, this unidirectionality is lacking and it is due to the fact that anions are usually less strongly bound than neutrals, whereas removing an electron from a bonding-type orbital usually gives localized modification in bond length and strength.

Original languageEnglish (US)
Pages (from-to)23120-23129
Number of pages10
JournalJournal of Physical Chemistry C
Issue number43
StatePublished - Nov 1 2012

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films


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