New Technique Allowing FT-Raman Measurements of Rotating Samples

Abstract

Sample rotation combined with Fourier transform (FT)-Raman spectroscopy usually results in spectra severely distorted by a double modulation of the scattered light emitted by the substance under study. In the case of accurately aligned solid samples, the disturbance modulation is mainly due to an optical inhomogeneity of the surface, e.g., a certain surface roughness. The application of the step-scan technique permits the laterally resolved investigation of rotating samples when the movement of the interferometer mirror of the FT-Raman spectrometer is synchronized to the rotation of the sample. Routine FT near-infrared (NIR) Raman spectroscopic measurements of thermally sensitive and inhomogeneous solid samples that require the application of a spinning-sample arrangement become possible. Moreover, information about the angular dependence of the physical and chemical surface composition of the solid samples, i.e., a lateral resolution, can be obtained.