2020, Muratov, A. V., Fronya, A. A., Antonenko, S. V., Kharin, A. Y., Aleshchenko, Y. A., Derzhavin, S. I., Karpov, N. V., Dombrovska, Y. I., Garmash, A. A., Kargin, N. I., Klimentov, S. M., Timoshenko, V. Y., Kabashin, A. V., Фроня, Анастасия Андреевна, Антоненко, Сергей Васильевич, Алещенко, Юрий Анатольевич, Гармаш, Александр Александрович, Каргин, Николай Иванович, Климентов, Сергей Михайлович, Тимошенко, Виктор Юрьевич, Кабашин, Андрей Викторович

Using methods of pulsed laser ablation from a silicon target in helium (He)-nitrogen (N2) gas mixtures maintained at reduced pressures (0.5-5 Torr), we fabricated substrate-supported silicon (Si) nanocrystal-based films exhibiting a strong photoluminescence (PL) emission, which depended on the He/N2 ratio. We show that, in the case of ablation in pure He gas, Si nanocrystals exhibit PL bands centered in the "red - near infrared" (maximum at 760 nm) and "green" (centered at 550 nm) spectral regions, which can be attributed to quantum-confined excitonic states in small Si nanocrystals and to local electronic states in amorphous silicon suboxide (a-SiOx) coating, respectively, while the addition of N2 leads to the generation of an intense "green-yellow" PL band centered at 580 nm. The origin of the latter band is attributed to a radiative recombination in amorphous oxynitride (a-SiNxOy) coating of Si nanocrystals. PL transients of Si nanocrystals with SiOx and a-SiNxOy coatings demonstrate nonexponential decays in the micro- and submicrosecond time scales with rates depending on nitrogen content in the mixture. After milling by ultrasound and dispersing in water, Si nanocrystals can be used as efficient non-toxic markers for bioimaging, while the observed spectral tailoring effect makes possible an adjustment of the PL emission of such markers to a concrete bioimaging task.

2021, Tikhonowski, G. V., Popova-Kuznetsova, E. A., Aleshchenko, Y. A., Klimentov, S. M., Kabashin, A. V., Popov, A. A., Тихоновский, Глеб Валерьевич, Попова-Кузнецова, Елена Алефтиновна, Алещенко, Юрий Анатольевич, Климентов, Сергей Михайлович, Кабашин, Андрей Викторович, Попов, Антон Александрович

© 2021, Allerton Press, Inc.Abstract: The effect of oxygen existing in an ablation medium during synthesis of titanium nitride (TiN) nanoparticles (NPs) by pulsed laser ablation in liquid (PLAL) on colloidal stability of obtained solutions was studied. It was shown that an increase in the oxygen content both incorporated in liquid molecules and in the form of dissolved gas increases the colloidal stability of synthesized NPs. The results obtained extend the range of available methods for developing new nanomaterials due to control of colloidal stability of laser-synthesized NPs.