A quantitative light-isotope measurement system for climate and energy applications

Abstract

We describe the design, operation, and performance of a new instrumental configuration capable of quantitative determinations with sub-picomole accuracy of dilute concentrations of low mass species, such as He4, He3, Ne20, and Ar40, in a balance of stable hydrogen (H2, DH, and D2) gas. This inexpensive system may realize important applications in fields ranging from climate studies to hydrogen fusion energy research, thereby providing an expanded availability of this diagnostic within emerging energy systems research and development. These spectra, calibration curves, and determinations were obtained by using a novel method for the purification and subsequent removal of the hydrogen matrix gas, and an extensively modified commercial Fourier Transform Ion Cyclotron Resonance (FT-ICR) mass spectrometer with an electron impact (EI) ionizer. These high-resolution FT-ICR mass spectrometers have routinely achieved a resolution, R = m/Δm better than 10,000 Da at mass-3, with a mass resolution that scales as 1/m. These devices have easily resolved D2 from He4, and DH from He3. The performance of this upgraded instrument has demonstrated the ability to detect impurities from tiny air leaks, such as Ar40 and Ne20, in the presence of the hydrogen matrix gas. While no concentration measurements of radioactive species have been attempted to date with this system, it is expected to easily resolve DT from D2H (a 0.0059 Da mass difference) and HT from all other mass-4 species.