LAUSR

Raman spectra of monodisperse crystalline diamond powders have been studied in dependence of the sample sizes. Raman scattering was excited by a near-IR cw laser (λ0 = 785 nm), which ensured suppression of the photoluminescence signal. Powders consisting of close-packed particles in the form of nanodiamonds (0.2–0.3 µm in size) and microdiamonds of specified sizes (up to 180 µm) have been studied. The recorded Raman spectra of the microdiamond powders are characterized by anomalously high intensity, which is related to the excitation radiation trapping in microparticles, the size of which exceeds significantly the lasing wavelength. The Raman spectra contain a sharp line at a frequency of 1332 cm–1 and additional bands in the vicinity of fundamental-mode overtones.