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Earth and Space Sciences · 术语表

什么是 Epsilon notation?

Definition 4.4 University Earth and Space Sciences — Year 2 · 第 4 章 — Isotope Geochemistry

The epsilon notation expresses the 143Nd/144Nd^{143}\mathrm{Nd}/^{144}\mathrm{Nd} ratio of a sample, at a time tt before the present, as its relative deviation from CHUR at the same time, in parts per ten thousand:

εNd(t)=((143Nd/144Nd)sample(t)(143Nd/144Nd)CHUR(t)−1)×104.\varepsilon_{\mathrm{Nd}}(t) = \left( \frac{(^{143}\mathrm{Nd}/^{144}\mathrm{Nd})_{\text{sample}}(t)} {(^{143}\mathrm{Nd}/^{144}\mathrm{Nd})_{\mathrm{CHUR}}(t)} - 1\right)\times 10^4 .

Without a time, εNd\varepsilon_{\mathrm{Nd}} is the present value.

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