Studies of dyestuffs in fibres by Fourier Transform Raman spectroscopy

Abstract

FT Raman spectroscopy is shown to be a powerful tool for the direct observation of low levels of dyestuffs in acrylic fibres. In the systems studied here, it is also found to yield more specific information than the complementary infrared technique. In contrast to conventional Raman spectroscopy with visible excitation, the near infrared laser used here does not induce fluorescence in the dye. Acrylic polymer bands can be efficiently subtracted to yield superbly detailed spectra of the dye in its physiochemical state in the fibre. The subtraction spectra provide valuable information on the nature of the dye and can be compared with spectra of pure dyes. Caution should be taken when subtracting spectra since small shifts in the frequency of the excitation laser line passing through the interferometer can generate artefacts in the final subtraction spectrum.