symbols: $\tilde{\nu}$, $\hat{\alpha}_{\rm{m}}$, unit: $\pu{J-1 C2 m2 mol-1}$
synonym: molar polarizability
https://doi.org/10.1351/goldbook.08634
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:
- The imaginary molar polarizability shows the absorption band free from long range dielectric effects that distort the band shapes of very strong absorptions.
- SI unit: \(\pu{J-1 C2 m2 mol-1}\).