The University of Tokyo · Earth and Planetary Sciences
Professor Takafumi Hirata's research lab specializes in advanced mass spectrometry techniques for high-precision isotope and elemental analysis of geological and environmental materials. The lab focuses on developing innovative methods to correct for instrumental fractionation and interferences in multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) and laser ablation-ICP-MS. Key research directions include improving isotopic measurement precision through novel calibration strategies, optimizing ablation techniques for stable signal acquisition, and minimizing spectral interferences—particularly in the analysis of U-Pb geochronology and trace elements in zircons. The lab also pioneers the use of specialized hardware, such as Hg-trap devices and controlled laser ablation protocols, to enhance data accuracy in challenging analytical conditions.
Figures are computed from collected data and may differ slightly.
A correction method for the mass discrimination effect was developed for isotopic analyses using multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS). For Pb isotopic analysis using MC-ICP-MS, the correction factor for the mass discrimination effect on Pb is based on the addition of TI to the sample solution and measurement of TI isotopic ratios; the correction factor obtained using Tl is directly applied to the Pb isotopes (conventional external correction). However, the
65Cu/63Cu and 56Fe/54Fe isotopic ratios for two metal reference materials (NIST SRM 976 and NIST SRM 665) have been measured by a laser ablation-multiple collector-inductively coupled plasma mass spectrometer (LA-MC-ICPMS). A time resolved analysis (TRA) data acquisition technique was used to monitor the time profile in 65Cu/63Cu and 56Fe/54Fe isotopic ratios. An ArF excimer laser (193 nm) which produces pit sizes of 16–63 µm was used to ablate Cu and Fe from metal samples. Measured 65Cu/63Cu ra
Precise 238U–206Pb ages for three Phanerozoic zircons (<600 Ma) have been measured using a laser ablation-ICPMS technique. In order to obtain reliable age data from young zircons, precise measurement of 204Pb intensity is highly important. To achieve this, a newly developed Hg-trap device using an activated charcoal filter was applied to the Ar make-up gas before mixing with He carrier gas, and the resulting isobaric interference on 204Pb by the 204Hg signal was significantly reduced. The level
A laser ablation technique has been developed for elemental and isotopic ratio analyses of solid materials using inductively coupled plasma mass spectrometry. Using a soft ablation technique developed in this study, reproducibility of the signal intensity and precision of the elemental and isotopic ratio measurement were successfully improved. The technique involves beginning the ablation at low laser power (lower than 1 mJ) and gradually increasing power to achieve a constant and stable signal.
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