VARIATIONS IN RELATIVE BAND INTENSITIES IN FOURIER-TRANSFORM RAMAN-SPECTRA AS A FUNCTION OF SAMPLE ALIGNMENT - PRELIMINARY-OBSERVATIONS

Polarized Fourier transform Raman spectra of samples of tetrahydrofuran and carbon tetrachloride were obtained as a function of sample displacement from the optimum focus of the spectrometer collection optics. It was found that the relative intensities of the Raman bands within a spectrum could vary significantly as a function of sample displacement. This was manifested predominantly as a suppression of strongly polarized bands near 1000 cm-1 Raman shift, although the absence of any variation in the CCl4 spectrum eliminates pure polarization effects as the sole cause of these observations. These results are important, as spectra of acceptable signal-to-noise ratio can be obtained with large sample displacements with this spectrometer, hence necessitating careful checking of the sample alignment when making quantitative measurements. The magnitude of the effects were extremely sample dependent.