Determination of bandshifts as a function of strain in carbon fibres using Raman microline focus spectrometry (MiFS)

Raman Microline Focus Spectrometry has been shown to have major advantages over conventional point focus Raman microscopy for the study of stress-induced shifts in carbon fibres. Averaged, representative spectra have been collected from a sample length of 140 μm, reducing possible errors in band positions incurred from localised stress and surface variations. In addition, it has been shown that data can be collected quickly at low laser powers, which avoid the localised heating effects experienced with point focus illumination. Unsized, pitch-based, carbon fibres, 6 μm in diameter, were studied during a strain-release cycle. Within the scatter of the data, the E 2g band returns to the original position when the tension is released. However, the A lg band remains downshifted by ca. −5.6 cm −1 upon release.