Biomedical Engineering Reference
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the broad diffraction lines of the cubic lattice of diamond with
average crystallite size of 3-5 nm.
Figure 6.1
Raman spectra of various carbon materials. (1) UDD K-2; (2)
UDD CH-7; (3) natural diamond; and (4) pyrolytic graphite.
Excitation wavelength—514 nm.
The main features of Raman spectra were similar for UDD of
different types as shown in Fig. 6.1, where the spectra of natural
diamond and pyrolytic graphite are reported for comparison.
The diamond sp
3
-line in the Raman spectra is broadened (FWHW
-1
-1
= 30-40 cm
in comparison with the
characteristic Raman peak of natural diamond (1332 cm
) and shifted to 1325 cm
-1
). This
behavior is typical of the nanodiamonds [67-69]. An additional broad
asymmetric band near 1600 cm
-1
-1
(FWHW ~100 cm
), assigned
2
to graphitic sp
-bonded carbon (G-peak) in the nanodiamonds
[67, 68] is also observed in the Raman spectra. UDD samples of
different origin were somewhat distinguished by the ratio of the
intensities of the diamond and graphite Raman peaks. The data of
thermal analysis did not show essential differences as regards the
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