Electrical Polarization and A.C. Conductivity

Following the discussion on ionic conductivity in section 12.1, and protonic conduction in section 12.1.2, it can definitely be seen that overall conduction in gum Arabica belongs to the aforementioned category. The nature of the mentioned conductivity is analyzed from a.c. conduction. In the microscopic level mechanism in the solid, there is a particular pair of states between which jumps take place which are influenced by the electric field. A dielectric material of natural type gum containing permanent dipole moment g, when sandwiched between two plane parallel electrodes of area A, separation d, the conductivity a and dielectric constant e are connected to conductance G and capacitance C by 7 = G (d/A) and = C (d/Eg A). In the absence of an external electric field, dipoles are oriented at random and possess only electronic polarizability in the field direction. 

An external electric field E orients the dipoles in the direction of the field, creating average total dipole moment along the field direction Total polarization P(t) = + Pj (t). The rate of change in total polarization P (t) 

The dielectric spectroscopy is an essential probe for nondestructive studies required for biomolecule analysis. The study of internal motion/dynamics related to the dielectric relaxation in biomolcules require the coverage of periodic vibration along with other mechanisms, such as diffusion, molecular orientations, and relaxation processes. 

Generally speaking, the material application of the electric field follows the relation expressed in Equation 12.7, 

This is known as a Debye dielectric response, where and 8 are the low and high frequency dielectric constant, and x is the time constant 

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