ИСТИНА

In our work we use porous silicon films, silicon nanowires arrays and mechanically grinded silicon microparticles (1 – 6 microns in size) as targets for picosecond (1064 nm, 34 ps, 10Hz) and femtosecond (1250 nm, 160 fs, 10Hz) pulsed laser ablation in liquids (PLAL). Ablation thresholds for the porous silicon and silicon nanowires targets in water and ethanol were demonstrated to be several times less in comparison to those for crystalline silicon, thus providing high-yield silicon nanoparticles (Si-NPs) production. Similar tendency is observed for laser fragmentation of silicon microparticles in these liquids. According to scanning electron microscopy and dynamic light scattering studies, the mean sizes of Si-NPs are in the range of 24 – 340 nm depending on the used target, buffer liquid, laser pulse duration and irradiation time. Raman spectroscopy data analysis revealed almost perfect crystallinity of the formed Si-NPs for silicon nanowires PLAL and laser fragmentation of the silicon microparticles. The studied Si-NPs exhibit fluorescence emission in the range of 600 – 900 nm which is most likely caused by internal structural defects in them [3]. Spectrophotometry measurements of the Si-NPs suspensions revealed their effective scattering in the spectral range of 400 – 1000 nm, which is explained in the frames of the Mie theory. Using the defined scattering and absorption parameters of the Si-NPs suspensions, the heating of tumor tissue with embedded nanoparticles was numerically modelled in order to evaluate their potential in tumor hyperthermia. The obtained results allow to conclude that the Si-NPs fabricated via PLAL are promising either in fluorescence and scattering bioimaging or in photohyperthermia of living organisms.