On the Possibilities of Detecting Surface Charges with Second Harmonic Generation and Optical Diagnostics of Polymeric Insulators

Abstract: Optical second-harmonic generation can be a sensitive probe of atoms and molecules at a surface or interface. For this reason, the method was chosen to study surface charges. Our measurements have been limited by large fluctuations in the frequency-doubled light and the mean value of the signals did not give any consistent changes due to changes in the surface charge. A solid metal constituted the sample but if the goal of the experiment had been to study any material configuration a silver-mica capacitor would have been a good choice due to earlier research. As the original intention of the project was to detect surface charges on polymeric insulators a natural generalisation of the project has been to characterise polymeric insulator materials and we have started this by studying biological growths, like algae and fungi. Both are crucial for the performance of the material. In cooperation with Andreas Demfalk at the Chalmers University of Technology the presence of algae and fungi could readily be remotely detected.