Principles and Practice of Chromatography - Factors Affecting the Magnitude of the Distribution Coefficient (K) > Molecular Forces > Dispersion Forces > Page 21

calculated to be (5),

 

where (a) is the polarizability of the molecule,

(no) is a characteristic frequency of the molecule,

(h) is Plank's constant,

and (r) is the distance between the molecules.

The dominant factor that controls the magnitude of the dispersive force is the polarizability (a) of the molecule, which, for substances that have no dipoles, is given by

 

where (D) is the dielectric constant of the material,