The Stark effect method

The Stark effect is related to a change in energy levels of atoms and molecules in the presence of a strong external electric field and is observed as a shift and splitting of the spectral rotational lines. The applicability of the method is restricted to the gas phase and more complex compounds require the use of isotopically labeled molecules [43,44,50-52]. 

The molecular beam method employs deflection of molecular beams in a nonuniform electric field. The displacement of the beam is used to calculate the dipole moment. Typically, the accuracy of this method is relatively low [3,53,54]. 

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Experimental dipole moments can be obtained in several different ways. The first and most widely used approach is based on the measurement of dielectric constants. The second group of methods utilizes microwave spectroscopy and molecular beams (the Stark effect method, the molecular beam method, the electric resonance method, Raman spectroscopy, etc.). 

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