KEYWORDS: Luminescence, Tomography, Silicates, Absorption, Chemical elements, Synchrotrons, X-ray microscopy, Chemical analysis, Signal attenuation, Iron
To settle an optimal analytical strategy of the search for life traces, it is decisive to start their study in the preliminary
examination stages of the extraterrestrial Returned Samples, once they are still stored in their original container. The
relevance of the application of on-going synchrotron micro-X-ray fluorescence (XRF) methodological developments
performed at the ID21/ID22 beamlines of the ESRF is critically examined in this paper. XRF computed tomography
(CT) at ID22 is in general a precious tool allowing a non-invasive and non-destructive determination of the three-dimensional
mineralogy with micrometer resolution of sub-millimeter silicate grains. A combination of absorption and
Compton tomographies is a more promising method to image bulk views of the organic matter distribution. XRF-scanning
X-ray microscopy (SXM) at ID21 is in general not adapted for studying samples across a container. However, it
appears to be a unique tool to draw up a list of the sub-surface sites where tiny amounts of organic matter are present.
Adaptation of the SXM chamber to the quarantine criteria stipulated by the spatial agencies is a way to permit such
analyses in the preliminary examination stages.
Since 1998 we have developed X-Ray fluorescence tomography for microanalysis. All aspects were tackled starting with the reconstruction performed by FBP or ART methods. Self-absorption corrections were added and combined with Compton, transmission and fluorescence tomographies to obtain fully quantitative results. Automatic "smart scans" minimized overhead time scanning/aligning non-cylindrical objects. The scans were performed step-by-step or continuously with no overhead time. Focusing went from 5 to 1 micron range, using FZP or CRL lenses, and finally KB bent mirrors which yield sub-micron high intensity beams. Recently, we have performed the first quantitative 3D fluo-tomography by helical scanning. We are now studying energy dependent fluo-tomography for chemically-sensitive imaging of the internal structure of samples. This chronology yielded the present level of sophistication for both experiments and data treatment and finally a method ready for wide dissemination among scientists.
We present recent results of fluorescence tomography experiments obtained on a variety of samples originating from the fields of Mineralogy, Space Sciences or Botany. The ID22 hard X-ray microanalysis beamline of the ESRF was used in scanning beam mode to record fluorescence spectra in pencil-beam collection mode for energies of 14 to 22.5 keV and micron-sized beamspots. Trace element concentrations of a few hundred ppm were successfully imaged in inhomogenous samples of less than 500 microns and resolutions up to 2 microns.
Conference Committee Involvement (2)
Instruments, Methods, and Missions for Astrobiology XII
4 August 2009 | San Diego, California, United States
Instruments, Methods, and Missions for Astrobiology XI
12 August 2008 | San Diego, California, United States
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.