Investigation of Biological Fibers Using Spontaneous and Stimulated Raman Technique

Spontaneous Raman scattering, Stimulated Raman Scattering (SRS) microscopy and Coherent Anti-Stokes Raman Scattering (CARS) microscopy were used to investigate: the orientation of specific vibrational modes in cellulose fibers, the presence of ordered water adsorbed into cellulose fibers and the distribution of deuterated sulfopropylacrylate in keratin fibers. Through these investigations it was found that the bond orientations of the methine and hydroxy stretching modes in cellulose fibers are oriented perpendicular and parallel to the long axis of the fiber, respectively. Through humidity-controlled Raman spectroscopy experiments with D2O, ordered deuterium hydroxide was detected in cellulose fibers and was found to align parallel to the long axis of the fiber. As the humidity was increased, the anisotropy of the OD-stretching band decreased as expected. Furthermore, it was found that as the humidity was increased the anisotropy of the CH- and OH-stretching regions did not change, supporting the findings of an ordered intercalation of water molecules into the fiber structure. Finally, hyperspectral SRS and Raman spectroscopy were applied to the detection of deuterated compounds in treated human hair samples provided to us by The Proctor and Gamble Company. From this investigation SRS was found to be able to detect the distribution of deuterated sulfopropylacrylate on high-level treated hairs, demonstrating the potential of SRS as a useful detection method for applications in the cosmetic industry.