Techniques have been developed for ion microprobe Pb-isotope dating of minerals at a lateral scale <5 m using the Cameca NanoSIMS 50. Probe spots 3-5 m in diameter comprising 16 keV 16 O − ions were utilized in the analyses by magnetic peak-switching of 204 Pb + , 206 Pb + , 207 Pb + , and 208 Pb + in NIST SRM 981 and 982 Pb metals, and ∼1 Ga uraninite, xenotime, and zirconolite reference materials. The Pb + mass resolution (M/ M at 1% peak height) was adjusted to ∼5000 to ensure the separation of molecular isobars. Under such conditions, the sensitivity for Pb + in zircon and zirconolite was 3.0-3.5 and ∼10 cps/ppm/nA 16 O − , respectively, about one-third the sensitivity obtained with large-geometry ion probes. Instrumental mass fractionation for Pb + was undetectable for SRM Pb metals and zirconolite, but values of up to 1.2% per atomic mass unit (enhancement of lighter isotopes) were recorded for xenotime and uraninite. As a demonstration of the technique, small zirconolite grains from a Cambrian mafic sill were analyzed in situ using a 3 m diameter probe. A mean 207 Pb * / 206 Pb * age of 504 ± 18 Ma was determined, and is considered an accurate measure of the crystallization age. Small-spot geochronology with the NanoSIMS at the present time is practical mainly for high-U mineral chronometers.

Richard A. Stern

Ian R. Fletcher

Birger Rasmussen

Neal J. McNaughton

Brendan J. Griffin

International Journal of Mass Spectrometry

该杂志邀请通过使用实验和理论方法探索离子过程的基本方面来推进质谱领域的论文，开发使用质谱进行化学分析的新仪器和实验策略，开发用于数据解释和集成的新计算策略，报告质谱和联用技术在生物学、化学、地质学和物理学中的新应用。将不考虑使用标准质谱技术进行分析的论文。IJMS 出版全篇文章、简短的交流、评论和专题文章包括年轻科学家的特点。

The International Journal of Mass Spectrometry invites researchers to explore the fundamental aspects of ion processes through experimental and theoretical methods, advancing the field of mass spectrometry. We welcome papers that develop new instruments and experimental strategies for mass spectrometry, as well as research on new computational strategies for data interpretation and integration. Additionally, we encourage reports on new applications of mass spectrometry and its coupled techniques in biology, chemistry, geology, and physics. Please note that papers using standard mass spectrometry techniques for analysis will not be considered. IJMS publishes full articles, brief communications, reviews, and special articles, with a particular focus on the contributions of young scientists.

国际质谱杂志邀请研究者通过实验和理论方法探索离子过程的基本方面，推动质谱领域的发展。我们欢迎开发新型质谱仪器和实验策略的论文，以及用于数据解释和集成的新计算方法的研究。同时，我们也鼓励报告质谱及其联用技术在生物学、化学、地质学和物理学等领域的新应用。请注意，使用标准质谱技术进行分析的论文将不予考虑。IJMS 发表全篇文章、简短交流、评论和专题文章，特别关注年轻科学家的研究成果。

Category	Quartile
化学	3
化学, 光谱学	3
化学, 物理原子、分子和化学物理	4

Ion microprobe (NanoSIMS 50) Pb-isotope geochronology at <5μm scale

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