Nu Instruments | Helium Isotope Ratios with Noblesse or Chronos
This note presents He isotope ratio measurements using Noblesse and explains why Chronos is also suitable for this application. It highlights peak jumping performance, low abundance sensitivity and precision close to counting-statistics limits.
The application note presents ³He/⁴He isotope data from a Noblesse configured with 1 Faraday and 3 multipliers. This configuration supports peak jumping for He and multicollection for other noble gases, while Chronos offers a smaller-volume option for He measurements.
Across 92 measurements over four days, ³He/⁴He was measured by peak switching, with ⁴He on the Faraday and ³He on the axial multiplier. The note also shows that ³He was fully resolved from HD, supporting accurate He isotope measurement.
The results demonstrate good precision and stability. Observed dispersion agrees closely with expected counting statistics, with precision reported to ±0.4% using helium with ³He/⁴He around 0.2 RA.
Key Takeaways:
- Noblesse and Chronos are both suitable for He isotope ratio measurement.
- ³He is fully resolved from HD during measurement.
- Precision agrees closely with the theoretical counting-statistics limit.
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