Untersuchungen zum oberflächenverstärkten Raman-Effekt auf Einzelmolekülebene

This paper is a report of measurements and single molecule experiments that were performed making use of the Surface Enhanced Raman Scattering (SERS) effect. First, different surfaces were prepared and characterized, after having been tested as to whether or not they were suitable as substrates for measurements on the single molecule level. Surfaces prepared from colloidal solutions of silver showed a high level of activity and were used for all further experiments. A simple variation on the preparation procedure allowed for an increase in the number of target molecule signals with a high signal-to-noise ratio.
However, samples prepared using the electrochemical double pulse method for silver particle deposits did not show sufficient activity for single molecule experiments.
A variety of rhodamine dyes as well as a number of further compounds were examined spectroscopically. The application of various derivatives served to define the influence of the chemical structure of a target molecule on the SERS-effect. In addition, the influence of the excitation wavelength was examined in detail.
Generalizable statements concering the mechanisms of the SERS effect could be made, based on the results obtained. Further, future experiments and optimalization procedures are suggested, in order to address outstanding questions.
Making measurements on the single molecule level made it possible to look at spectroscopic events which are normally hidden under multiple molecules conditions. Of further significance is that most of the compounds investigated had never before been examined at this level.