  Systematic Raman experiments performed on water and water-ethanol samples,
stored in different containers (fused silica, polypropylene, soda-lime glass
type III) for several hours, have shown that the luminescence contribution to
the Raman signal fluctuations is directly related to the container composition.
Intensity fluctuations as large as 98%, have been observed in the spectral
regions corresponding to the both water intramolecular and intermolecular
vibrations, despite the fact that the wavenumbers of the modes remained
unchanged. We undoubtedly attribute these fluctuations to a luminescence
phenomenon on the basis of : i) the absence of such effect in the anti-Stokes
domain, ii) its dependence on the excitation laser wavelength, iii) other
relevant photoluminescence experiments. This luminescence is attributed to
pollutants at ultra-low concentration coming from the different containers.
