ASTID

High-resolution X-ray Spectro-microscopy: Understanding Biological Fingerprints in the Geological Record (2)

PI: Stephan Friedrich

Our team proposes to adapt superconducting soft X-ray detectors for operation at an X-ray microscope to combine the high sensitivity and high spectral resolution of superconducting spectrometers with the high spatial resolution of an X-ray microscope. Such an instrument will enable sensitive speciation measurements on biominerals with a spatial resolution of ~30 nm by fluorescence-detected soft X-ray absorption spectroscopy. Soft X-rays are a sensitive probe of an element’s chemical state, and microscopy allows spatial separating putative biominerals from nearby abiotic forms of the same element, as well as mapping of speciation gradients. The instrument will be used to characterize known biogenic transition metal minerals, identify distinguishing features from abiotic materials, and establish potential fingerprints of biological activity in the geological record. These measurements will be initially performed on terrestrial biogenic and abiotic mineral samples, and eventually extended to geological and meteorite fragments. Building on existing collaborations, this proposal brings together leading experts in superconducting detector technology (S. Friedrich, LLNL), X-ray microscopy (D. Kilcoyne, M. LeGros, LBNL), X-ray spectroscopy (S. P. Cramer, S.J. George, LBNL/UCD), bio-geochemistry (B. Tebo, UCSD; R. Flegal, UCSC) astrobiology (K. Nealson, USC, J. Cervini-Silva, UCB) and meteorites/ interplanetary dust (J. Bradley, LLNL). The instrument will be operated at the X-ray Microscopy beam lines at the Advanced Light Source at Lawrence Berkeley National Lab and will be available to the scientific community on a proposal basis.