SIZE EFFECTS APPEARING IN THE RAMAN-SPECTRA OF POLYCRYSTALLINE DIAMONDS

Various spectra of Raman for different grain sizes of diamond powder have been studied. The spectra are also correlated to the results of transmission electron diffraction, transmission electron microscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy. When the Raman peak intensity was decreased, the spectra broadened and shifted to a lower frequency in accordance with the decrease of the grain size. Finally, in the region of a few hundred angstroms, the detected signals were almost comparable to the noise level. While unchanged, lattice spacings for transmission electron diffraction patterns and constant peak heights for x-ray photoelectron spectroscopy analysis were observed for different grain sizes.