We have measured Raman spectra of diamond with nanometer size, called cluster diamond. The Raman bands assigned to sp2 and sp3 clusters have been observed at around 1600 and 1322 cm−1, respectively. This result suggests that the cluster diamond slightly contains the sp2 cluster. The Raman band assigned to sp3 cluster is found to shift by −10 cm−1, compared with that of bulk crystal and to be asymmetric with some tailing toward lower Raman frequency. The observed Raman spectrum agrees well with that calculated by a phonon confinement model. The crystallite size of the cluster diamond estimated from the phonon confinement model agrees approximately with that estimated from x-ray measurement. Raman spectroscopy gives some information about the crystallite size of diamond particles with nanometer size.

Raman spectra of diamond powders with size less than 2 μm have been measured as a function of the particle size. The Raman line was found to become more asymmetric with some tailing towards lower Raman shifts, broader, and weaker with decreasing particle size. The observed result can be explained by a phonon confinement effect rather than by a strain effect. This work predicts that it is very difficult to detect Raman spectra of diamond particles with size less than ∼50 Å. A broad Raman band, whose intensity becomes stronger with decreasing particle size, was observed around 600 cm−1 in the spectra of diamond powders with particle size less than 2 μm. We hypothesize that the broad band arises from transverse acoustic phonons near the Brillouin zone boundary because of the relaxation in the wave vector selection rule.

Polarized Raman spectra around trenches formed on (100) silicon wafers have been measured and it has been found that the peak frequency shift varies with the polarization configuration, suggesting that anisotropic stresses occur around the trenches. The different stress components have been calculated by the use of the polarization Raman technique and it was found that the stress distribution of each component approximately agrees with that of each component simulated by a finite element method. Polarized Raman spectroscopy is a powerful technique for the estimation of an anisotropic stress of an electronic silicon device in situ.

147V Quadrupole Coupling. Table III shows the coupling constants of pyrrole-Ar (first numerical column), the coupling constants of pyrrole relabeled to most closely correspond to the principal axes of the complex (third and fourth columns), and the coupling constants predicted by rotating pyrrole's principal axes 6.7°to coincide with the principal axes of the complex (second column). The agreement between the observed coupling constants and those predicted by this transformation is very good given the uncertainties in the structural parameters and vibrational averaging effects. The observed constants are 2-3% smaller than the predicted values, suggesting that the electric field gradient at the N atom is the same in the complex as in pyrrole except that there is some essentially isotropic vibrational averaging in the complex.

No abstract