Molar refractivity, , is a measure of the total polarizability of a mole of a substance and is dependent on the temperature, the index of refraction, and the pressure.
The molar refractivity is defined as
is the Avogadro constant and is the mean polarizability of a molecule.
Substituting the molar refractivity into the
Lorentz-Lorenz formula gives
For a gas,
, so the molar refractivity can be approximated by
SI units, has units of J mol −1 K −1, has units K, has no units, and has units of Pa, so the units of are m 3 mol −1.
In terms of
density, ρ molecular weight, M it can be shown that:
References [ edit ]
Born, Max, and Wolf, Emil, Principles of Optics: Electromagnetic Theory of Propagation, Interference and Diffraction of Light (7th ed.), section 2.3.3, Cambridge University Press (1999) ISBN 0-521-64222-1