features of the phenomena of a laser nanosecond radiation In supercritical carbon dioxide are revealed. It is shown that the presence of a supercritical fluid leads to the expansion of the structures formed on the target in comparison with the air media. It has been suggested that the resulting magnification effect is due to the defocusing of the system, which causes the formation of the lens impact. Obtaining useful results is possible with the use of various technologies of laser ablation and microstructuring in supercritical fluids.

The mechanism of action of laser radiation during fiber perforation of water-saturated materials in the case when laser radiation is well absorbed in water is refined. It is shown that due to the explosive boiling of water in the pores, as well as a decrease in the tensile strength and an increase in the plasticity of the material, a layer of highly porous tissue is formed near the end of the laser fiber, which contributes to a significant increase in the perforation rate.

It has been experimentally found that when the end face of an optical fiber with an absorbing coating is heated by continuous laser radiation with a wavelength of 0.97 μm, submerged jets are periodically generated in water. Each such jet is formed as a result of the collapse of a gas-vapor bubble arising from the explosive boiling of water. The mechanisms of formation of bubbles and jets are discussed.

Продемонстрирована возможность получения сверхкритической воды при поглощении лазерного импульса длительностью 8 нс пленкой золота толщиной 50 нм, находящейся в контакте с водой. Для оценки возникающего вблизи пленки скачка давления использовали измерение акустического давления в дальней зоне с помощью гидрофона на основе кристалла ниобата лития. Оценку скачка температуры проводили по реперной точке - температуре плавления золота. Показано, что при энергии лазерных импульсов 65 мкДж тонкий слой воды, контактирующий с металлической пленкой, находится в сверхкритическом состоянии в течение ~ 4,5 нс. The work uses the possibility of formation supercritical water (SCW) upon absorption of a laser pulse with a duration of 8 ns by a 50 nm thick gold film, which is in contact with water. To estimate the growth of the pressure jump film, we used an approach based on measuring the acoustic pressure in the far field using a hydrophone based on a lithium niobate crystal. The temperature jump was estimated using a reference point - the melting point of gold. It is shown that at a laser pulse energy of 65 mJ, a thin layer of water in contact with a metal film is in a supercritical state for ~ 4.5 ns.

Laser printing with gel microdroplets is a promising method for biotechnology and medicine. During printing, a nanosecond laser pulse is absorbed in a thin metal film of a donor substrate with a covered gel layer, which leads to its heating, partial destruction of the film, and transfer of a gel microdroplet to the acceptor substrate. In this work, the dynamics of destruction of a film with a thickness of 50 nm is studied. It is shown that when threshold is exceeded, the gold film peels off from the glass plate. A further increase in the laser fluence occurs to the formation of a orifice in the film. The results obtained are of interest for improving the technology of laser bioprinting.

It was found experimentally that when the water surface is heated by CW laser radiation through the optical fiber with a wavelength of 1.94 μm, jets are generated : one is submerged, directed inward liquid, the other directed in the opposite direction into the atmosphere. Jets are formed when the gas cavity collapses, arising in the process of explosive boiling of water caused by absorption of laser radiation directly under the fiber tip. The mechanism of jet formation is discussed.

Спроектирована и изготовлена установка для получения нанесенных гетерогенных катализаторов методом лазерной абляции металлической мишени в присутствии носителей различной природы в среде сверхкритического диоксида углерода (СК-С0). Выбраны условия импульсного лазерного воздействия (длина волны, частота, время), параметры среды СК-С0 (давление, температура) и конфигурация узлов установки (лазер, мишень, носитель и элементы визуального и оптического контроля). На этой установке при лазерной абляции металлического палладия осаждением на у-оксид алюминия в среде СК-С0 получен композит, представляющий собой AlO с частицами Pd. При изучении синтезированного композита в качестве катализатора жидкофазного гидрирования дифенилацетилена показана его высокая активность (TOF = 1,45 с) и высокая селективность в гидрировании одной тройной связи. An experimental setup was created to produce deposited heterogeneous catalysts by laser ablation of a metal target in the presence of various carriers in supercritical carbon dioxide (SC-CO). The conditions of pulsed laser exposure (wavelength, frequency, and time), SC-CO medium parameters (pressure, temperature) and the configuration of experimental setup (laser, target, carrier and visual and optical control elements) were worked out. A composite consisting of AlO with Pd particles was obtained by laser ablation of metal palladium with deposition onto у-alumina in a SC-CO medium. The synthesized composite has been studied as a catalyst for liquid-phase hydrogenation of diphenylacetylene and its high activity (TOF = 1.45 s) and high selectivity in hydrogenation of one triple bond has been shown.