Raman spectroscopic identification of usnic acid in hydrothermal minerals as a potential Martian analogue
Language English Country England, Great Britain Media print-electronic
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
18980859
DOI
10.1016/j.saa.2008.09.005
PII: S1386-1425(08)00469-1
Knihovny.cz E-resources
- MeSH
- Benzofurans analysis MeSH
- Exobiology methods MeSH
- Crystallization MeSH
- Mars MeSH
- Extraterrestrial Environment chemistry MeSH
- Minerals chemistry MeSH
- Spectrum Analysis, Raman methods MeSH
- Calcium Sulfate chemistry MeSH
- Calcium Carbonate chemistry MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- Benzofurans MeSH
- Minerals MeSH
- Calcium Sulfate MeSH
- Calcium Carbonate MeSH
- usnic acid MeSH Browser
Raman spectroscopy using 785 nm excitation was tested as a nondestructive method for determining the presence of the potential biomarker, usnic acid, in experimentally prepared mineral matrices. Investigated samples consisting of usnic acid mixed with powdered hydrothermal minerals, gypsum and calcite were studied. Various concentrations of usnic acid in the mineral matrix were studied to determine the detection limits of this biomarker. Usnic acid was mixed with gypsum (respectively, calcite) and covered by a UV-transparent crystal of gypsum (CaSO(4) x 2 H(2)O), thereby creating artificial inclusions similar to those which could be present in Martian minerals. A Raman usnic acid signal at the concentration level as low as 1 g kg(-1) was obtained in the powdered mineral matrix and 5 g kg(-1) when analyzed through the monocrystal. The number of registered usnic acid key Raman bands was dependent on the particular mineral matrix. If a similar concentration of usnic acid could persist in Martian samples, then Raman spectroscopy will be able to identify it. Obtained results will aid both in situ Raman analyses on Mars and on Earth.
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