Schwingungsspektroskopische Untersuchung ausgewaehlter heterozyklischer Pflanzenschutzmittel: SERS-Spektroskopie an der Grenzflaeche fest/fluessig und ab initio Berechnungen

In this work the behaviour of N-heterocyclic pesticides at the solid/liquid interface has been studied by means of Raman and surface enhanced Raman (SERS) spectroscopy. The aim was first to prove the possibilities of SERS as an analytical method for the determination of pesticides and second to present the abilities of quantum mechanical calculations as a tool for the interpretation of vibrational data. Using a combination of thin layer chromatrography (TLC) and SERS enabled us to even traces of pesticides (nanogram range) in organic materials. The efficiency of this combination could be enhanced by a new kind of SERS activation. Instead of applying the often used silver colloids a thin film of silver was evaporated onto the TLC plates delivering three orders of magnitude higher SERS signals. An excessive SERS spectra interpretation of all pesticides presented in this work had been done showing the power of quantum mechanical ab initio calculation as a tool in the area of predicting vibrational spectroscopic data. For example, for all in situ prepared redox forms of the model pesticide paraquat (methylviologen) the same vibrational pattern was found while a dependence of line position from binding order could be concluded. Furthermore, a new kind opto-electrochemical flow-through cell was developed, being so small that it fits in every commercial available Raman spectrometer. By means of this cell a on-line determination of water soluble pesticides could be demonstrated. The time necessary for the adsorption of the molecules, the acquisition of the SERS spectrum and finally the desorption of the pesticides lay in the order of seconds. (orig.)SIGLEAvailable from TIB Hannover: RA 831(3573) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman