TeraHertz Dielectric Spectrometer (UPV/EHU)

Dielectric spectroscopy consists in the study of the frequency dependent complex dielectric permittivity of insulator materials. The frequency range more commonly investigated is below a few GHz where the dielectric response of the insulator materials is usually dominated by orientational polarization processes. If the material under investigation contains permanent dipoles with a molecular origin, the dielectric spectroscopy would allow to get insight about the molecular motions.

 

This spectrometer allows covering the highest frequencies, up to ~4 THz, where the time scale of dipolar reorientation superimpose on that of slow molecular vibrations. The sample is iluminated with broaband THz pulsed radiation and the transmited electric field is mesured. After Fourier transformation, traditional absorption and transmission spectra are obtained after dividing the sample frequency response by that of the instrument. In addition, by using the phase information, the frequency dependence of the refractive index and complex dielectric permitivity can be obtained.