METHOD FOR DETERMINING CHEMICAL CONSTITUENTS OF SOLID OR LIQUID SUBSTANCES WITH THE AID OF THZ SPECTROSCOPY

摘要

The invention relates to a method for determining chemical constituents of solid or liquid substances with the aid of THz spectroscopy, wherein the substances are caused to oscillate by the THz radiation and at least the reflected portions of the radiation are detected and the respective reflection spectrum is evaluated. The aim of the invention is for said method to be usable under difficult boundary conditions at a wide variety of atmospheric water vapour concentrations. Said aim is achieved in that, before evaluating the respective reflection spectrum, the respective detected raw spectrum is subjected to a pre-treatment, wherein in a first pre-treatment step the influence of the water bands in the respective raw spectrum is eliminated by means of spike filters, in a second pre-treatment step the respective raw spectrum is subjected to a base line correction, and in a third pre-treatment step high-frequency portions of the raw spectrum are eliminated by means of smoothing.