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Pure and Applied Chemistry

The Scientific Journal of IUPAC

Ed. by Burrows, Hugh / Stohner, Jürgen

IMPACT FACTOR 2017: 5.294

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Volume 83, Issue 5


IUPAC-IUGS common definition and convention on the use of the year as a derived unit of time (IUPAC Recommendations 2011)

Norman E. Holden / Mauro L. Bonardi / Paul De Bièvre
  • Corresponding author
  • Consultant on Metrology in Chemistry, Duineneind 9, B-2460 Kasterlee, Belgium
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/ Paul R. Renne / Igor M. Villa
Published Online: 2011-04-08 | DOI: https://doi.org/10.1351/PAC-REC-09-01-22

The units of time (both absolute time and duration) most practical to use when dealing with very long times, for example, in nuclear chemistry and earth and planetary sciences, are multiples of the year, or annus (a). Its proposed definition in terms of the SI base unit for time, the second (s), for the epoch 2000.0 is 1 a = 3.1556925445 × 107 s. Adoption of this definition, and abandonment of the use of distinct units for time differences, will bring the earth and planetary sciences into compliance with quantity calculus for SI and non-SI units of time.

Keywords: annus; decay constants; geochronology; IUPAC Analytical Chemistry Division; IUPAC Inorganic Chemistry Division; SI units; units of time

Project Year: 2006, Project Code: 2006-016-1-200


  • 1

    IUPAC. Quantities, Units and Symbols in Physical Chemistry, 3rd ed. (the “Green Book”). Prepared for publication by E. R. Cohen, T. Cvitaš, J. G. Frey, B. Holmström, K. Kuchitsu, R. Marquardt, I. Mills, F. Pavese, M. Quack, J. Stohner, H. L. Strauss, M. Takami, A. J. Thor, p. 137, RSC Publishing, Cambridge, UK (2007).Google Scholar

  • 2

    IUPAP. Symbols, Units and Nomenclature and Fundamental Constants in Physics, <http://metrology.wordpress.com/measurement-process-index/iupap-red-book/>.Google Scholar

  • 3

    Recommendations concerning Units. Reprinted from the “IAU Style Manual” by G. A. Wilkinson, Comm. 5, in IAU Transactions XXB (1987). <http://www.iau.org/science/publications/proceedings_rules/units/>.Google Scholar

  • 4

    A. Thompson, B. N. Taylor. Special Publication 811: Guide for the Use of the International System of Units (SI), National Institute of Standards and Technology (NIST), Gaithersburg, MD, USA (2008).Google Scholar

  • 5

    BIPM. Le Système international d’unités – The International System of Units SI, 8th ed., Bureau International des Poids et Mesures, Geneva (2006). <http://www.bipm.fr/fr/si/si_brochure/>.Google Scholar

  • 6

    The 11th General Conference on Weights and Measures (GGPM), Resolution 9; CR 86 (1960).Google Scholar

About the article

Published Online: 2011-04-08

Published in Print: 2011-04-08

Citation Information: Pure and Applied Chemistry, Volume 83, Issue 5, Pages 1159–1162, ISSN (Online) 1365-3075, ISSN (Print) 0033-4545, DOI: https://doi.org/10.1351/PAC-REC-09-01-22.

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