Detecting Kerogen as a Biosignature Using Colocated UV Time-Gated Raman and Fluorescence Spectroscopy

Svetlana Shkolyar, Evan J. Eshelman, Jack Farmer, David Hamilton, Michael G. Daly, Cody Youngbull

Research output: Contribution to journalReview article

4 Citations (Scopus)

Abstract

The Mars 2020 mission will analyze samples in situ and identify any that could have preserved biosignatures in ancient habitable environments for later return to Earth. Highest priority targeted samples include aqueously formed sedimentary lithologies. On Earth, such lithologies can contain fossil biosignatures as aromatic carbon (kerogen). In this study, we analyzed nonextracted kerogen in a diverse suite of natural, complex samples using colocated UV excitation (266 nm) time-gated (UV-TG) Raman and laser-induced fluorescence spectroscopies. We interrogated kerogen and its host matrix in samples to (1) explore the capabilities of UV-TG Raman and fluorescence spectroscopies for detecting kerogen in high-priority targets in the search for possible biosignatures on Mars; (2) assess the effectiveness of time gating and UV laser wavelength in reducing fluorescence in Raman spectra; and (3) identify sample-specific issues that could challenge rover-based identifications of kerogen using UV-TG Raman spectroscopy. We found that ungated UV Raman spectroscopy is suited to identify diagnostic kerogen Raman bands without interfering fluorescence and that UV fluorescence spectroscopy is suited to identify kerogen. These results highlight the value of combining colocated Raman and fluorescence spectroscopies, similar to those obtainable by SHERLOC on Mars 2020, to strengthen the confidence of kerogen detection as a potential biosignature in complex natural samples.

Original languageEnglish (US)
Pages (from-to)431-453
Number of pages23
JournalAstrobiology
Volume18
Issue number4
DOIs
StatePublished - Apr 1 2018

Fingerprint

fluorescence emission spectroscopy
kerogen
Raman spectroscopy
fluorescence spectroscopy
Raman Spectrum Analysis
Fluorescence Spectrometry
Mars
fluorescence
spectroscopy
Lasers
Fluorescence
sampling
lasers
lithology
mars
Carbon
Mars missions
laser induced fluorescence
aromatic compounds
wavelengths

Keywords

  • Biosignatures
  • Kerogen
  • Laser-induced fluorescence spectroscopy
  • Mars 2020 mission
  • Mars Sample Return
  • Raman spectroscopy

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Detecting Kerogen as a Biosignature Using Colocated UV Time-Gated Raman and Fluorescence Spectroscopy. / Shkolyar, Svetlana; Eshelman, Evan J.; Farmer, Jack; Hamilton, David; Daly, Michael G.; Youngbull, Cody.

In: Astrobiology, Vol. 18, No. 4, 01.04.2018, p. 431-453.

Research output: Contribution to journalReview article

Shkolyar, Svetlana ; Eshelman, Evan J. ; Farmer, Jack ; Hamilton, David ; Daly, Michael G. ; Youngbull, Cody. / Detecting Kerogen as a Biosignature Using Colocated UV Time-Gated Raman and Fluorescence Spectroscopy. In: Astrobiology. 2018 ; Vol. 18, No. 4. pp. 431-453.
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