scholarly journals Laser-Induced Damage Threshold of Nonlinear GaSe and GaSe:In Crystals upon Exposure to Pulsed Radiation at a Wavelength of 2.1 μm

2021 ◽  
Vol 11 (3) ◽  
pp. 1208
Author(s):  
Chongqiang Zhu ◽  
Victor Dyomin ◽  
Nikolay Yudin ◽  
Oleg Antipov ◽  
Galina Verozubova ◽  
...  
Keyword(s):  
Repetition Rate ◽  
Pulse Repetition Rate ◽  
Peak Power ◽  
Damage Threshold ◽  
Radiation Energy ◽  
Incident Radiation ◽  
Pulse Repetition ◽  
Optical Parametric Oscillators ◽  
Parametric Oscillators ◽  
Laser Induced Damage

The paper defined the laser-induced damage threshold from the fluence and the peak power of GaSe and GaSe:In single crystals upon exposure to nanosecond radiation in the two micron range and assessed the influence of test radiation energy parameters (pulse repetition rate, pulse duration) on the damage threshold. Laser-induced damage threshold was determined with the parameters of the incident radiation close to the pump radiation parameters of promising dual-wavelength optical parametric oscillators (effective pump sources for THz difference frequency oscillators): wavelength was ≈2.1 μm; pulse repetition rates were 10, 12, 14, and 20 kHz; and pulse durations were 15, 18, 20, and 22 ns. The obtained results made it possible to conclude that the value of GaSe damage threshold at a wavelength of 2.091 μm of the incident radiation was influenced by the accumulation effects (the damage threshold decreased as the pulse repetition rate increased). The accumulation effects were more significant in the case of the In-doped sample, since a more significant decrease in the damage threshold was observed with increasing frequency in terms of the peak power and the fluence.

scholarly journals Two Approaches to the Laser-Induced Formation of Au/Ag Bimetallic Nanoparticles in Supercritical Carbon Dioxide

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1553
Author(s):  
Alexey Rybaltovsky ◽  
Evgeniy Epifanov ◽  
Dmitriy Khmelenin ◽  
Andrey Shubny ◽  
Yuriy Zavorotny ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Ag Nanoparticles ◽  
Repetition Rate ◽  
Pulse Repetition Rate ◽  
Bimetallic Nanoparticles ◽  
Side Wall ◽  
Pulse Repetition ◽  
Gold Core ◽  
Supercritical Carbon

Two approaches are proposed for the synthesis of bimetallic Au/Ag nanoparticles, using the pulsed laser ablation of a target consisting of gold and silver plates in a medium of supercritical carbon dioxide. The differences between the two approaches related to the field of “green chemistry” are in the use of different geometric configurations and different laser sources when carrying out the experiments. In the first configuration, the Ag and Au targets are placed side-by-side vertically on the side wall of a high-pressure reactor and the ablation of the target plates occurs alternately with a stationary “wide” horizontal beam with a laser pulse repetition rate of 50 Hz. In the second configuration, the targets are placed horizontally at the bottom of a reactor and the ablation of their parts is carried out by scanning from above with a vertical “narrow” laser beam with a pulse repetition rate of 60 kHz. The possibility of obtaining Ag/Au alloy nanoparticles is demonstrated using the first configuration, while the possibility of obtaining “core–shell” bimetallic Au/Ag nanoparticles with a gold core and a silver shell is demonstrated using the second configuration. A simple model is proposed to explain the obtained results.

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