Performance Optimization of a Large Geometry High Resolution-Secondary Ion Mass Spectrometer (HR-SIMS) for High Precision Measurements of Oxygen Isotopic Composition (δ 18 O) and U-Pb Geochronology in Zircon

A large geometry high resolution secondary ion mass spectrometer (HR-SIMS) has been established as a part of the National Geochronology Facility (NGF) at Inter-University Accelerator Centre (IUAC), New Delhi. The performance of the instrument related to high spatial resolution, high mass resolving p...

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Published in:Journal of mass spectrometry. 2025-01, Vol.60 (1), p.e5103
Main Authors: Khandelwal, Deeksha, Kumar, Pankaj, Kumar, P V, Singh, Atul K, Rawat, Mahadev, Dawar, Anit, Sharma, R, Ojha, S, Gargari, S, Mukherjee, P K, Chopra, S, Pandey, A C
Format: Article
Language:English
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Summary:A large geometry high resolution secondary ion mass spectrometer (HR-SIMS) has been established as a part of the National Geochronology Facility (NGF) at Inter-University Accelerator Centre (IUAC), New Delhi. The performance of the instrument related to high spatial resolution, high mass resolving power (MRP), sensitivity of the instrument to measure low abundant isotopes, and sensitivity of the instrument for Pb signal under different conditions are optimized and presented in this paper. We report the precision of the order of ~ 0.2‰ for oxygen isotopes measurement in 91500 reference material zircon and measured δ O value of 10.08‰ ± 0.18‰ (2SD), which is in agreement with the recommended values. For U-Pb age measurement in zircon, Plešovice and FCT reference materials are measured as unknown and their Pb/ U ages agree with the reported values within the uncertainties. A long-term evaluation of Pb/ UO and Pb/ U isotopic measurement ratio is also presented.
ISSN:1096-9888
1096-9888
DOI:10.1002/jms.5103