IUPAC > Gold Book > alphabetical index > R > rotational diffusion coefficient


rotational diffusion coefficient

Defined by the equation:
D θ = t θ ∂ ( f θ Φ ) ∂ θ sin ⁡ θ
where f θ Φ sin ⁡ θ d θ d Φ is the fraction of particles whose axes make an angle between θ and θ + d θ with the direction θ = 0, and have an azimuth between Φ and Φ + d Φ; t θ d Φ is the fraction of particles having an azimuth between Φ and Φ + d Φ whose axis passes from values < θ to values > θ in unit time. The axis whose rotational diffusion is considered has to be clearly indicated.
PAC, 1972, 31, 577 (Manual of Symbols and Terminology for Physicochemical Quantities and Units, Appendix II: Definitions, Terminology and Symbols in Colloid and Surface Chemistry) on page 617
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IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: http://goldbook.iupac.org (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook.
Last update: 2014-02-24; version: 2.3.3.
DOI of this term: doi:10.1351/goldbook.R05411.
Original PDF version: http://www.iupac.org/goldbook/R05411.pdf. The PDF version is out of date and is provided for reference purposes only. For some entries, the PDF version may be unavailable.
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