Sorry, but I cannot understand completely the problem: what kind of experimental data do you have?What do you mean for Cp' and Cp"? What do you want to determine?

Hello Sudhanshu,

From an R + C loop, impedance is expressed like:

Z = R / (1 + iRC*2πf) where R is the resistance, C the capacitance, i*i=-1 and f the frequency of the signal.

Z' and Z" are the real and the imaginary part of z respectively

I hope it helped you…

Best,

Robin

ok. But, i dont have R. I have to calculate Z' and Z'' and i have sigma', sigma'', tan(delta), Cp' and Cp''. So, i cannot understand how to that.

I do not understand… Are Cp' and Cp" two different capacitors? what do you mean by sigma' and sigma", or delta? can you attach a file with a figure of your model electronic circuit?

Did you make your meaurements in an electrochmeical setup? I think you should clarify your question with some details, for example: 1) what Measurements you have done? 2) what is your target system? and 3) what data you have recorded? If your meaurements are done in an electrochemical system using a potentiostat, at a given potential you can directly measure both Z'' and Z' to make a Niquist plot. The electrochemical software can also automatically interconvert different plots, for example from the Niquist plot to the Capacitance vs frequency plot. I am not completely sure why you need to calculate.  

This can be done via the software of your workstation. Anyway, the direct mathematical equation for the impedance Z of any capacitor C is as follows: Z = 1/j 2πfC, where f is the frequency of the ac signal at which C is measured and j is the square root of (-1).