Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

UP: Fachverband Umweltphysik

UP 10: Neuartige Verfahren in der Umweltphysik

UP 10.2: Vortrag

Donnerstag, 13. März 2008, 09:15–09:30, 3B

Laser ablation (LA) multi ion counter (MIC) MC-ICPMS techniques for U-Th isotope measurements in Quaternary climate research — •Dirk Hoffmann — Bristol Isotope Group, University of Bristol, Bristol, UK

High precision mass spectrometry is an important technique in environmental physics and Earth Sciences. For example, isotope measurements of elements such as U-Th-Pb are essential for U-series dating of palaeoclimate archives and are useful tracers of diverse physical processes in the oceans, in magma chambers or of weathering. There is an increasing demand for higher precisions, smaller detection limits and thus smaller sample sizes that can be analysed. I investigate the application of novel techniques in the field of mass spectrometry applied to environmental research including multi ion counter (MIC) arrays available for the ThermoFinnigan Neptune MC-ICPMS and micro sampling techniques such as laser ablation (LA) or micromilling. MIC increase the efficiency of low level ion beam collection by allowing simultaneous collection of all ion beams which also circumvents problems associated with unstable, transient beams often associated with laser ablation. In situ LA MC-ICPMS is an ideal tool for U-Th measurements at very high spatial resolution without prior chemical separation procedures. However, small beam intensities and matrix effects especially for mass and elemental fractionation pose significant analytical problems for accurate determinations of U-Th ratios. I present analytical procedures developed at Bristol Isotope Group for LA U-Th dating of carbonates and discuss potential and limitations for palaeoclimate research.