Development of Ce Isotope Analysis for Cosmochemistry Using the Dynamic Multicollector Technique

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Precise and accurate Ce isotope analysis technique was developed with one order of magnitude smaller ion beam intensity compared with previous studies to apply ¹³⁸La-¹³⁸Ce decay system to smaller samples. ¹³⁸Ce/¹⁴²Ce and ¹³⁶Ce/¹⁴²Ce isotope ratios were accurately determined by canceling not only the fluctuation of ion beam intensities but also the Faraday cup efficiencies and amplifier gains with the dynamic multicollector technique. In situ ¹⁸O/¹⁶O determination for Ce¹⁸O correction and ¹⁴⁰Ce/¹⁴²Ce normalization for mass fractionation were applied to the accurate analysis. A repeated analysis of ¹³⁸Ce/¹⁴²Ce and ¹³⁶Ce/¹⁴²Ce ratios of a Ce isotopic reference, JMC304, were 0.0225889±0.0000013 and 0.0168810±0.0000030. This technique has almost the same precision and reproducibility in comparison with previous Ce isotope studies, and will be suitable for samples with limited amount like extra-terrestrial materials, including detection of p-process nuclide anomalies of ¹³⁸Ce and ¹³⁶Ce.