Luminescence excitation wavelength limitations

Fixed wavelength and synchronous scanning fluorescence suffer from non-selectivity and are generally Ineffective in structural elucidation (particularly for mixtures). Despite the ability to select both the excitation and emission wavelengths, the conventional luminescence methods have limited applicability since most spectra of complex mixtures often cannot be satisfactorily resolved. The use of a computer-controlled total scanning fluorometer can overcome many of the limitations of previous methods. 

The optical setup for time-resolved micro-luminescence measurements is based aroimd an Axiotech 100 HD Zeiss microscope, modified to allow laser injection and fluorescence collection. The sample is observed either under transmission or reflection of polarized white light, or tmder UV illumination (HBO lamp). A set-up consisting on a dichroic mirror, for the selection of the excitation wavelength, and an objective (Epiplan Neofluar obj. >350 run EaUng/Coherent reflection obj. <350 nm) is used to focus the laser beam on the sample (spatial resolution over 5 pm with a x50 objective). The limitation of the spatial resolution is mainly... 

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