**3.1 Nanosecond laser fluorescence spectrometer**

A homemade laser fluorimeter (Fig. 3) has been built for the experiments. The fluorimeter consist of a laser source, optical elements for light conversion, a fiber-optic cable, a cuvette and an optical multichannel analyser.

Fig. 3. Nanosecond laser fluorescence spectrometer scheme (for details see text). The letters H, V and C denote the horizontal, vertical and circular light polarization.
