Raman spectra of various diamonds.

Abstract

We measured Raman spectra of diamonds in ureilite meteorites and of diamonds synthesized under static high pressure, under shock-induced high pressure, and by chemical vapor deposition. The full width at half maximum (FWHM) and wavenumber position of a Raman line of F2g (at 1332 cm−1) are compared. Both the wavenumber and FWHM of the Raman line of ureilite diamonds are somewhat scattered around 1332 cm−1 compared with those of diamonds produced under static high pressure. The latters show spectral features similar to the diamonds from the earth. The peak positions of some ureilite diamonds are shifted to smaller wavenumber than 1332 cm−1, possibly due to lonsdaleite (hexagonal diamond). The peak position of the shock-produced diamonds is significantly shifted to smaller wavenumber, probably due to lonsdaleite and the FWHM is largely deviated. The FWHM of CVD diamonds is narrower than that of the shock-produced diamonds but larger than that of the diamonds synthesized under static high pressure. The peak position of some CVD diamonds tends to shift to higher wavenumber unlike shock-produced diamonds. The values of the FWHM of ureilite diamonds is closer to those of CVD diamonds than those of shock-produced diamonds.