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Development of a non-destructive micro-analytical method for stable carbon isotope analysis of Transmission Electron Microscopy (TEM) samples
Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
2009 (English)In: Nuclear Instruments and Methods in Physics Reseach B, ISSN 0168-583X, Vol. 267, no 19, 3375-3382 p.Article in journal (Refereed) Published
Abstract [en]

The biogenicity of ancient morphological microfossil-like objects can be established by linking morphological (e.g. cell remnants and extracellular polymeric matrix) and chemical (e.g. isotopes, biomarkers and biominerals) evidence indicative of microorganisms or microbial activity. We have developed a non-destructive micro-analytical ion beam system capable of measuring with high spatial resolution the stable carbon isotope ratios of thin samples used for transmission electron microscopy. The technique is based on elastic scattering of alpha particles with an energy of 2.751 MeV. At this energy the 13C cross section is enhanced relative to the pure Rutherford cross section for 13C, whereas the 12C cross section is reduced relative to its pure Rutherford cross section. Here we report the initial results of this experimental approach used to characterize ultramicrotomed sections of sulfur-embedded graphite and microbial cells.

Place, publisher, year, edition, pages
Elsevier B.V. , 2009. Vol. 267, no 19, 3375-3382 p.
Keyword [en]
Astrobiology; Rutherford scattering; Carbon isotopes; TEM
National Category
Natural Sciences
URN: urn:nbn:se:su:diva-23764DOI: 10.1016/j.nimb.2009.06.116OAI: diva2:194394
Part of urn:nbn:se:su:diva-477Available from: 2005-04-27 Created: 2005-04-27 Last updated: 2010-09-21Bibliographically approved
In thesis
1. The Search for Life on Mars - Preparation for Sample Return
Open this publication in new window or tab >>The Search for Life on Mars - Preparation for Sample Return
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The purpose of the thesis work has been to develop methods and concepts to aid in the search, detection and assessment of ancient microfossils here on Earth as a guide to the search for ancient life on Mars. The intention has been to identify and characterize environments on Earth that may be considered analogous to Martian environments and in which fossil preservation is expected to be good, and to develop and apply methods to characterize the isotopic and chemical composition of possible traces of life in order to assess their biogenicity and biological affinities.

An investigation of the Siljan impact structure, Sweden, demonstrated that niches for thermophilic organisms were created in the associated hydrothermal system. The temperature regimes were favorable for thermophilic life in the outer parts of the structure during the early and main stages of the hydrothermal system, but that these niches moved toward the center of the crater during the final cooling stages. It was demonstrated that the hydrothermal system contains traces of a thermophilic microbial community, represented by fossilized extracellular polymeric substances (EPS). Given the presence of water on Mars, similar impact-induced hydrothermal systems were probably generated on Mars as well. These regions, like those at Siljan, may have supported hyperthermophilic microbial communities on the red planet, emphasizing the relevance of searching for impact-induced hydrothermal deposits for evidence of microbial life on Mars.

A method for the determination of stable carbon isotopes with high lateral resolution of TEM (transmission electron microscopy) samples has been developed. The method is based on alpha-particle Rutherford backscattering (RBS), it is non-destructive, and therefore suitable for analysis of extraterrestrial and other rare or irreplaceable material. Also, a novel concept to extract fluid inclusions without ablating the sample has been proposed, and a proof-of-concept has been demonstrated. The purpose is to analyze organic biomarkers trapped in fluid inclusions without risking contamination, and also to extract and analyze single fluid inclusions. The minimized contamination risk and the potential to extract single fluid inclusions could make the method a useful tool in the search for organic biomarkers in early-Earth material, and eventually, in samples returned from Mars.

Place, publisher, year, edition, pages
Stockholm: Institutionen för geologi och geokemi, 2005. 21 p.
Meddelanden från Stockholms universitets institution för geologi och geokemi, ISSN 1101-1599 ; 323
National Category
Earth and Related Environmental Sciences
urn:nbn:se:su:diva-477 (URN)91-7155-086-0 (ISBN)
Public defence
2005-05-20, filmsalen, Naturhistoriska riksmuséet, Frescativägen 40, Stockholm, 13:15
Available from: 2005-04-27 Created: 2005-04-27Bibliographically approved

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