Luminescent properties of nanoparticles created by laser ablation of natural diamond single crystals

The formation of particles during ablation of single crystals of natural diamond by laser radiation with a wavelength of 213 nm was studied. As a result of ablation, diamond particles of two characteristic sizes are formed. The linear size of large particles was on the order of 1 µm, small particles – from 300–400 nm and less. The spectra and kinetics of luminescence of the original crystal and the resulting nanoparticles were recorded. Measurements showed that the spectra of nano- and microparticles are radically different from the spectra of the original single crystals. The luminescence of nanoparticles did not manifest the characteristic structure of spectra and the corresponding decay time constants of luminescence of N3 and H3 color centers observed in the original single crystals. Instead, a broad complex luminescence band with several different decay time constants was observed. It was found that this luminescence is caused by the products of graphitization of the surface of nano- and microparticles, as well as the surface of a crater formed on a diamond single crystal as a result of ablation. The absorption of optical radiation that excited luminescence in the experimental studies of particles and craters was so strong that the luminescence of the main diamond composition of nanoparticles and a diamond crystal under the graphitized layer was not detected in experiments.