Resonanz-Ramanspektren transienter Molekülzustände stark fluoreszierender Farbstoffe

In many cases a comparatively simple model is capable to explain the absorption of visible light in a qualitative and quantitative matter. Inelastic scattering leads to a stimulation of molecular vibrations. Both interactions are used to determine important properties of molecules. The discussion of the achievable sensitivity on the quantification of the power of light leads to criteria for the choice of a detector. With the help of a transient-state spectrometer the absorption of excited states of dye molecules is measured. This data is essential for the experiments related to resonant raman scattering on transient states. Using a raman-spectrometer for weakly fluorescent probes, the necessary sensitivity is determined. Origin and magnitude of the noise level are studied carefully. The results give clues to several optimisation strategies. A modulation technique for suppression of the fluorescence by 2-λ- excitation is presented and the results are analyzed. Obligations and key parameters of the monochromator are examined with respect to the signal-to-noise ratio. The necessary improvements are accomplished in the raman microscope. Its function is optimised till the measurement of raman spectra of excited states of strongly fluorescent dyes is achieved. The properties of the vibrational spectra of rhodamine dyes are discussed with respect to literature data and quantum-mechanical calculations.