Acquisition of Experimental Gas Source Mass Spectrometer for Stable Isotope Geochemistry

California Institute Of Technology, Pasadena CA

Investigators

Abstract

0220066 Eiler This grant provides partial support for an experimental gas source isotope ratio mass spectrometer commissioned from Thermo-Finnigan. This instrument will provide routine analytical capabilities needed to support our existing programs in the hydrogen isotope geochemistry of the solid earth and atmospheric reduced gases. Furthermore (and more importantly), it will be the first ever built with an experimental collection system designed to simultaneously measure relative abundances of common isotopomers (e.g., 12C16O16O, 13C16O16O and 12C18O16O measured in conventional mass spectrometry of CO2) and very rare isotopomers containing two or more rare isotopes (e.g., 12C18O18O, 13C18O16O and 13C18O18O). These species have unusual thermodynamic properties that suggest they can be used to develop intramolecular geothermometers; we also anticipate that their distribution in nature is influenced by non-equilibrium isotope fractionations, such as result from metabolisms, photochemical reactions, and mass transport. The natural geochemistry of these very rare isotopomers is unexplored and promises to add new dimensions to our understanding of the natural cycles of common molecular gases (e.g., N2, O2, CO, CO2, N2O - all of which will be analyzable using this instrument. ***