Single Molecule Surface-Enhanced Raman Spectroscopy: A Critical Analysis of the Bianalyte versus Isotopologue Proof

Alyssa B. Zrimsek, Nolan L. Wong, Richard P. Van Duyne*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

102 Scopus citations

Abstract

Verification of single-molecule (SM) detection for surface-enhanced Raman spectroscopy (SERS) requires the use of two analytes via either the bianalyte or isotopologue approach. For both approaches, the preferential observation of the individual analytes over a combination of both analytes is used to conclude that SM detection has been achieved. Isotopologues are preferred because they have identical surface binding affinities and Raman cross sections, whereas bianalyte pairs typically do not. We conducted multianalyte SERS studies to investigate the limitations of the bianalyte approach. The bianalyte partners, Rhodamine 6G (R6G-d0) and crystal violet (CV-d0), were directly compared, while SM detection was verified (or disproved) using their corresponding isotopologues (R6G-d4, CV-d12). We found that the significant difference in counts between R6G and CV can provide misleading evidence for SMSERS. We then rationalized these results using a joint Poisson-binomial model with unequal detection probabilities and adjusted the relative concentrations of R6G and CV to achieve a comparable distribution of SMSERS counts. Using this information, we outlined the necessary considerations, such as accounting for the differences in molecular properties, for reliable SMSERS proofs. Moreover, we showed that multianalyte experiments at the SM level are achievable, opening the opportunity for new types of SM studies.

Original languageEnglish (US)
Pages (from-to)5133-5142
Number of pages10
JournalJournal of Physical Chemistry C
Volume120
Issue number9
DOIs
StatePublished - Mar 17 2016

Funding

We thank Dr. Bogdan Negru for help with MATLAB and Dr. Ash Younai for synthesizing the deuterated analytes. A.B.Z. acknowledges support from the National Science Foundation (CHE-1506683). N.L.W. acknowledges support from the Air Force Office of Scientific Research MURI (FA9550-14-1-0003) and the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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