An experimental determination of the polarization and molecular electric dipole moments

8 An experimental determination of the polarization and molecular electric dipole moments 

Experimental determination of microscopic characteristics is based on the Debye-Langevin (eq. (4.2.28)) and Lorentz-Lorentz (eq. (4.2.30)) equations. They connect macroscopic molecular characteristics, measured directly in physical experiment, with microscopic ones. Measuring dielectric permeability s in an electrostatic field, the molar polarization 11 can be found  

Measurements of a refraction index n in an optical range of frequencies allows us to find the molar refraction R, and consequently, the molecule electron polarizability using eq. (4.2.30) (R = or 

The orientation polarization a p, corresponding to a given temperature, can also be found from the graph the angle coefficient tan y is determined by a p. Indeed, 

The tan y value is determined by expression An/A (1/7) m C/mol. Therefore, the slope has the same dimension. Note that decreases with deaease in temperature. Knowing a , we can determine the molecular dipole moment. According to eq. (4.2.19), p =3sQKTa substituting further according to eq. (4.2.36), we can obtain p =(9INa)SoK tan y, from which 

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