Raman spectra are reported from single crystals of graphite and other graphite materials. Single crystals of graphite show one single line at 1575 em-I. For the other materials like stress-annealed pyrolitic graphite, commercial graphites, activated charcoal, lampblack, and vitreous carbon another line is detected at 1355 em-I. The Raman intensity of this band is inversely proportional to the crystallite size and is caused by a breakdown of the k-selection rule. The intensity of this band allows an estimate of the crystallite size in the surface layer of any carbon sample. Two in-plane force constants are calculated from the frequencies.

No abstract

Raman spectroscopy is used to characterize the fiber surface of graphite and carbon fibers. A correlation exists between the Raman spectrum of the fiber surface and the shear strength of the com posite. Effects of surface treatments are reflected in the Raman spec trum as well as the shear strength of the composite. Many graphite fibers have a weak surface layer where the graphite planes are oriented parallel to the surface.

No abstract

No abstract