{"term":{"id":"08634","title":"local molar polarizability","longtitle":"IUPAC Gold Book - local molar polarizability","doi":"10.1351\/goldbook.08634","code":"08634","status":"current","synonym":"<em>synonym<\/em>: molar polarizability","definitions":[{"id":1,"text":"Defined under the assumption of the Lorentz local field by the Lorentz-Lorenz formula: \\[\\hat{\\alpha}_{\\rm{m}}(\\tilde{\\nu}) = 3V_{\\rm{m}}\\epsilon_{0} \\frac{\\hat{\\epsilon}(\\tilde{\\nu}) - 1}{\\hat{\\epsilon}(\\tilde{\\nu}) + 2} = 3V_{\\rm{m}}{\\epsilon}_{0}\\,\\frac{\\hat{n}^{2}(\\tilde{\\nu}) - 1}{\\hat{n}^{2}(\\tilde{\\nu}) + 2}\\] where \\(V_{\\rm{m}}\\) is the molar volume and \\(\\hat{\\epsilon}\\) and \\(\\boldsymbol{\\hat{n}}\\) are the complex dielectric constant and refractive index, respectively. To allow description of absorption, \\(\\hat{\\alpha}_{\\rm{m}}(\\tilde{\\nu})\\) is complex: \\(\\hat{\\alpha}_{\\rm{m}}(\\tilde{\\nu}) = \\alpha_{\\rm{m}}'(\\tilde{\\nu}) + \\rm{i}\\alpha_{\\rm{m}}''(\\tilde{\\nu})\\).","notes":{"1":"The imaginary molar polarizability shows the absorption band free from long range dielectric effects that distort the band shapes of very strong absorptions.","2":"SI unit: \\(\\pu{J-1 C2 m2 mol-1}\\)."},"links":[{"term":"band shapes","url":"https:\/\/goldbook.iupac.org\/\/terms\/view\/08574"}],"sources":["PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 753 (https:\/\/doi.org\/10.1515\/pac-2019-0203)"]}],"altoutputs":{"html":"https:\/\/goldbook.iupac.org\/terms\/view\/08634\/html","xml":"https:\/\/goldbook.iupac.org\/terms\/view\/08634\/xml","plain":"https:\/\/goldbook.iupac.org\/terms\/view\/08634\/plain"},"citation":"Citation: 'local molar polarizability' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351\/goldbook.08634","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":"2026-06-10T14:22:08+00:00"}}