ИСТИНА

This work presents results of experiments of the nanoparticle formation as a result of ultrafast laser ablation of porous silicon in water and helium. During the experiment the target was irradiated with Cr:forsterite femtosecond (1250 nm, 180 fs, 10 Hz, 10 J/cm2) and Nd:YAG picosecond (1064 nm, 30 ps, 10 Hz, 7 J/cm2) laser pulses at room temperature. The choice of porous silicon as a material for experiments is caused by a lower threshold of ablation in comparison with crystalline silicon. During the ablation of the crystalline silicon ablation threshold is equal to1 J/cm2, whereas for porous materials threshold equals 0,1 J/cm2. This feature leads to a greater exit of substance at lower energy costs at a case of ablation of porous silicon Due to the efficient light scattering of porous silicon the nanoparticles formed by ablation of por-Si could be used as contrasting agents for visualization of model biosimilar environments by methods of optical diagnostics [1]. In addition the electronic properties of silicon nanoparticles with small size (less than 5 nm) allow using them as photoluminescent labels for photodynamic therapy and diagnosis [2].The size of nanoparticles fabricated via laser ablation was determined by atomic-force microscopy (AFM) and ranges from 10 to 60 nm. The samples with minimum size of nanostructures was obtained at a case of ablation in helium at pressure 500 mbar. By means of a Raman scattering spectroscopy the phase structure of the created nanoparticles was defined. This work was financially supported by the Russian Foundation for Basic Research (project 15-32-20227). [1] M.Yu Kirillin, E.A. Sergeeva, P.D Agrba et al., “Laser-ablated silicon nanoparticles: optical properties and perspectives in optical coherence tomography”, Laser Physics 25, 075604 (2015). [2] P. Jusenas, W. Chen., YP. Sun, et al., “Quantim dots and nanoparticles for photodynamic and radiation therapies of cancer”, Adv. Drug Delivery Rev. 60, 1600-1614 (2008).