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Pure and Applied Chemistry

The Scientific Journal of IUPAC

Ed. by Burrows, Hugh / Weir, Ron / Stohner, Jürgen

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1365-3075
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Volume 83, Issue 5 (Apr 2011)

Issues

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

Norman E. Holden
  • Corresponding author
  • International Union of Pure and Applied Chemistry
/ Mauro L. Bonardi
  • Corresponding author
  • International Union of Pure and Applied Chemistry
/ Paul De Bièvre
  • Corresponding author
  • Consultant on Metrology in Chemistry, Duineneind 9, B-2460 Kasterlee, Belgium
/ Paul R. Renne
  • Corresponding author
  • Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94720, USA
/ Igor M. Villa
  • Corresponding author
  • Institut für Geologie, Universität Bern, CH-3012 Bern, Switzerland
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

References

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About the article

Published Online: 2011-04-08

Published in Print: 2011-04-08


Citation Information: Pure and Applied Chemistry, ISSN (Online) 1365-3075, ISSN (Print) 0033-4545, DOI: https://doi.org/10.1351/PAC-REC-09-01-22.

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