Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability
- Univ. of California, Berkeley, CA (United States)
Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of 235U/238U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser in a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 1035969
- Report Number(s):
- LLNL-TH-500731; TRN: US1201309
- Country of Publication:
- United States
- Language:
- English
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Rate equation model of laser induced bias in uranium isotope ratios measured by resonance ionization mass spectrometry
Rate equation model of laser induced bias in uranium isotope ratios measured by resonance ionization mass spectrometry
Related Subjects
74 ATOMIC AND MOLECULAR PHYSICS
42 ENGINEERING
22 GENERAL STUDIES OF NUCLEAR REACTORS
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
ABUNDANCE
ATOMS
FEEDBACK
FRACTIONATION
IONIZATION
ISOTOPE RATIO
LASERS
MASS SPECTROSCOPY
PROBABILITY
PURIFICATION
RESONANCE
SAMPLE PREPARATION
TARGETS
URANIUM
URANIUM ISOTOPES
URANIUM OXIDES
WAVELENGTHS