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ALT'23 The 30th International Conference on Advanced Laser Technologies
LD-I-18
Study of colloid nanoparticles in aqueous solutions by ultramicroscopy and dynamic light scattering
G^. Silaev1'3, F.V. Vereschagin1, А.T. Shaydulin23, Yu.V. Оrlovskii2,
Yu.G. Vainer13
1-Institute of Spectroscopy RAS, Moscow, Troitsk, 108840 Russia 2- Prokhorov General Physics Institute of RAS, Moscow, 119991 Russia 3- Higher School of Economics, National Research University, Moscow, 101000 Russia
E-mail: vainer@isan. troitsk. ru
The development of optical methods for studying colloidal nanoparticles in aqueous environments is one of the topical areas of nanophotonics. In particular, the development of methods that allow visualization and study of nanoparticles at the single particle level is highly relevant. Electron and probe microscopy methods, widely used for these purposes (tunneling, atomic force, optical near-field, etc.), have a number of fundamental drawbacks. They are characterized by a complex sample preparation and measurement procedure, are unsuitable for studying nanoparticles in aqueous environments, may have unwanted effects on the sample, and are not very accessible. Optical far-field microscopy methods are free from most of the listed drawbacks and are characterized by high efficiency, a significantly simpler measurement procedure, and a low effect on the sample.
In the overwhelming majority of cases, nanoparticles are studied in the form of powders or suspensions, which leads to distortion of information about the individual properties of the particles. Therefore, the development of methods for studying and visualizing nanoparticles at the single particle level is also one of the topical areas of modern science.
The talk reports the development of a highly sensitive laser ultramicroscope operating on the "light sheet" scheme, which allows visualization of single nanoparticles in aqueous solutions with sizes of up to 20 nanometers or less and determination of their individual sizes from the signals of light elastic scattering by analyzing the individual trajectories of their Brownian motion. The results of optical diagnostics of colloidal solutions of single dielectric nanocrystals of lanthanum fluoride - LaF3 doped with europium (Eu3+) and ne-odymium (Nd3+) ions, with sizes within 10-30 nm, and their conglomerates using the developed microscope and developed methods are also reported. The results of comparative measurements of the sizes of the same nanoparticles using electronic and developed microscopes, as well as ensemble measurements of nanoparti-cles and their suspensions in water using the method of dynamic light scattering (DLS), are also presented.
Special attention is paid to the analysis of the experimental data obtained on the clusters formed on the basis of the studied colloidal nanoparticles, in order to gain a deeper understanding of the information about the properties of the particles obtained using the listed optical methods.
The research was supported by the Russian Science Foundation project No. 22-22-00998
