The expression above can also be written in terms of individual molecules by expressing the dependence on refractive index in terms of the molecular polarizability α, proportional to the dipole moment induced by the electric field of the light. In this case, the Rayleigh scattering intensity for a single particle is given in CGS-units by I s = I 0 8 π π 4 α α 2 λ λ 4 R 2 ( 1 + cos 2 ⁡ ⁡ θ θ ) and in SI-units by I s = I 0 π π 2 α α 2 ε ε 0 2 λ λ 4 R 2 1 + cos 2 ⁡ ⁡ ( θ θ ) 2 .