Development of a surface-enhanced Raman technique for biomarker studies on mars

Darrell S. Dunn*, Narasi Sridhar, Michael A. Miller, Kendra T. Price, Roberto Pabalan, Teofilo Abrajano

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    8 Scopus citations

    Abstract

    Raman spectroscopy has been identified as a potentially useful tool to collect evidence of past or present life on extraterrestrial bodies. However, it is limited by its inherently low signal strength. In this investigation, laboratory tests were conducted using surface-enhanced Raman spectroscopy (SERS) in an "inverted" mode to detect the presence of organic compounds that may be similar to possible biomarkers present on Mars. SERS was used to overcome the inherently low signal intensity of Raman spectroscopy and was an effective method for detecting small concentrations of organic compounds on a number of surfaces. For small organic molecules, dissolution of the molecule to be analyzed in a suitable solvent and depositing it on a prepared SERS substrate for analysis is possible. However, for larger molecules, an "inverted" SERS (iSERS) technique was shown to be effective. In iSERS, nanoparticles of silver or gold were deposited on the mineral substrate/organic compound to be analyzed. Benzotriazole, benzoic acid, and phthalic acid were used as test organic analogs and the iSERS technique was able to detect femtomole levels of the analytes. The interference from various mineral substrates was also examined. Different methods of depositing silver particles were evaluated, including ion beam-assisted vapor deposition and deposition from aqueous colloidal suspensions.

    Original languageEnglish (US)
    Pages (from-to)25-31
    Number of pages7
    JournalApplied Spectroscopy
    Volume61
    Issue number1
    DOIs
    StatePublished - Jan 1 2007

    Keywords

    • Mars
    • Organic biomarkers
    • Raman spectroscopy
    • SERS
    • Surface-enhanced Raman spectroscopy

    ASJC Scopus subject areas

    • Instrumentation
    • Spectroscopy

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