I can see, to the best of my knowledge, that Dielectric Relaxation Spectroscopy - DRS - (for some, Impedance Spectroscopy) data is well stressed for reverse micelles or microemulsions at higher frequencies, above MHz range, and very few papers deal with below MHz range experiments. If the electrode or interfacial polarization is a problem I guess there are some methods to remove this effect from the data or even from the measurement, like highly porous electrodes. Then I wonder, is that a still open area of research? Or is there some fundamental issues about using low frequencies to characterize static or dynamic properties of reverse micelles or microemulsions using DRS?
There are two issues here. The first is the frequency range. If you are looking at measuring a standard Maxwell-Wagner type interfacial polarisation process then, because the "particles" in such emulsions are very small, the dispersions tend to occur in the high frequency ranges. Only if you want to look at interfacial polarisation process in the boundary layers will you need to go to the lower frequencies. The problem then tends to be electrode polarisation when electrodes are used that are in direct contact with the emulsion. However, contactless methods have been developed which typically use magnetically fields to reach the emulsion. Hewlett Packard used to market a contactless probe for this purpose to be used in conjunction with one of their standard impedance analysers. I belive they have stopped this some time ago, but I would still contact them first to see whether they can help.
Thanks for the answer Prof Gerard. I can understand that at low frequencies we will look primarily for interfacial polarization, and my doubt question was done because the regular potentiostats that we have access just work up to 1 MHz, and a dedicated device, like a HP for example, costs much more, and sometimes is not available. I know two papers from Rosario Gerhardt, from GeorgiaTech, where she proves that one relaxation process will be shown at different frequencies for different dielectric functions (permittivity, impedance, dielectric loss, electrical modulus); and then I thought even if in impedance one can see mainly electrode processs, if we use another dielectric function we could see some bulk process. Anyway, thanks again for the help, and have a good new year.
It is possible to reduce electrode polarisation - use of a 4 electrode method does help, as does fitting models to the low frequency electrode polarisation and subtracting this from the measured spectra. I expect however that wthout a high-frequency plateau to work with bulk processes will be difficult to measure.
The main limitation you will find is electrode polarization. I would not advise using 4 electrode system to by pass this as this will bring unexplained processes into your picture as a result of non-linear fields near the sampling electrodes. Your best bet is to use difference techniques (you may gain a decade) and temperature variation. afterwards algorithmic techniques can help to clean the signal further. For papers on microemulsions and dielectric spectroscopy follow Yuri Feldman
https://www.researchgate.net/profile/Yuri_Feldman2/