Testing the validity of terahertz reflection spectra by dispersion relations

Complex response function obtained in reflection spectroscopy at the terahertz range is examined with algorithms based on dispersion relations for integer powers of complex reflection coefficient, which emerge as a powerful and yet uncommon tools in examining the consistency of the spectroscopic data. It is shown that these algorithms can be used in particular for checking the success of the correction of the spectra by the methods of Vartiainen [J. Appl. Phys. 96, 4171 (2004)] and Lucarini [Phys. Rev. B. 72, 125107 (2005)] to remove the negative misplacement error in the terahertz time-domain spectroscopy.