{"term":{"id":"05159","doi":"10.1351\/goldbook.R05159","code":"R05159","status":"current","longtitle":"IUPAC Gold Book - Rayleigh ratio","title":"Rayleigh ratio","termversion":"2.3.3","lastupdated":"2014-02-24","definitions":[{"id":"1","text":"The quantity used to characterize the scattered intensity at the scattering angleθ, defined as R(θ) = iθr2\/IfV, where I is the intensity of the incident radiation, iθ is the total intensity of scattered radiation observed at an angleθ and a distance r from the point of scattering and V is the scattering volume. The factor f takes account of polarization phenomena. It depends on the type of radiation employed. For light scattering, dependent on the polarization of the incident beam, f = 1 for vertically polarized light, f = 1 - cos^2 θ for horizontally polarized light and f = (1 + cos^2 θ)\/2 for unpolarized light. For small-angle neutron scattering, f = 1. For small-angle X-ray scattering, f ≈ 1, if θ < ca. 5°. ","notes":{"1":"The dimension of R(θ) is (length-1).","2":"In small-angle neutron scattering the term cross-section is often used instead of R(θ); the two quantities are identical.","3":"An alternative recommended symbol is R(θ)."},"links":[{"title":"angle","type":"goldify","url":"https:\/\/goldbook.iupac.org\/terms\/view\/A00346"},{"title":"neutron","type":"goldify","url":"https:\/\/goldbook.iupac.org\/terms\/view\/N04116"},{"title":"scattering","type":"goldify","url":"https:\/\/goldbook.iupac.org\/terms\/view\/S05487"},{"title":"scattering angle","type":"goldify","url":"https:\/\/goldbook.iupac.org\/terms\/view\/S05488"},{"title":"polarization","type":"goldify","url":"https:\/\/goldbook.iupac.org\/terms\/view\/P04712"},{"title":"light scattering","type":"goldify","url":"https:\/\/goldbook.iupac.org\/terms\/view\/L03525"}],"math":[{"alttext":"θ","latex":"\\theta"},{"alttext":"R(θ) = iθr2\/IfV","latex":"R(\\theta) = \\frac{i_{\\theta }\\,r^{2}}{I\\,f\\,V}"},{"alttext":"I","latex":"I"},{"alttext":"iθ","latex":"i_{\\theta}"},{"alttext":"θ","latex":"\\theta"},{"alttext":"r","latex":"r"},{"alttext":"V","latex":"V"},{"alttext":"f","latex":"f"},{"alttext":"f = 1","latex":"f=1"},{"alttext":"f = 1 - cos^2 θ","latex":"f = 1 - \\cos^{2}\\theta"},{"alttext":"f = (1 + cos^2 θ)\/2","latex":"f = 1 + \\frac{\\cos^{2}\\theta}{2}"},{"alttext":"f = 1","latex":"f=1"},{"alttext":"f ≈ 1","latex":"f \\approx 1"},{"alttext":"θ < ca. 5°","latex":"\\theta < \\text{ca.}\\ 5\\,°"},{"alttext":"R(θ)","latex":"R(\\theta)"},{"type":"dimension","alttext":"(length-1)","latex":"(\\text{length})^{-1}"},{"alttext":"R(θ)","latex":"R(\\theta)"},{"alttext":"R(θ)","latex":"R_{\\theta}"}],"sources":["Purple Book, 1st ed., p. 65 (http:\/\/old.iupac.org\/publications\/books\/author\/metanomski.html)"]}],"referencedin":[{"title":"Wikipedia - User talk:Michael zh (en)","url":"https:\/\/en.wikipedia.org\/wiki\/User_talk:Michael_zh"},{"title":"Wikipedia - Співвідношення Релея (uk)","url":"https:\/\/uk.wikipedia.org\/wiki\/Співвідношення_Релея"}],"links":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/R05159\/html","json":"https:\/\/goldbook.iupac.org\/terms\/view\/R05159\/json","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/R05159\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/R05159\/plain","pdf":"https:\/\/goldbook.iupac.org\/terms\/view\/R05159\/pdf"},"citation":"Citation: 'Rayleigh ratio' in IUPAC Compendium of Chemical Terminology, 3rd ed. International Union of Pure and Applied Chemistry; 2006. Online version 3.0.1, 2019. 10.1351\/goldbook.R05159","license":"The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/) for individual terms.","collection":"If you are interested in licensing the Gold Book for commercial use, please contact the IUPAC Executive Director at executivedirector@iupac.org .","disclaimer":"The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.","accessed":"2024-07-12T12:12:03+00:00"}}